EN ISO 22477-5 Testing of anchorages DPC.pdf

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Title:

Draft ENISO 22477-5 Geotechnical investigation and testing - Testing of geotechnical geotechnical structures Part 5: Testing of anchorages

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Introduction This draft standard is based on international discussions in which the UK has taken an active part. Your comments on this draft are invited and will assist in the preparation of the consequent standard. Comments submitted will be reviewed by the relevant BSI committee before sending the consensus UK vote and comments to the international secretariat, which will then decide appropriate action on the draft and the comments received. If the international standard is approved, it is possible the text will be published as an identical British Standard. UK Vote Please indicate whether you consider the UK should submit a negative (with reasons) or positive vote on this draft. Submission The guidance given below is intended to ensure that all comments receive efficient and appropriate attention by the responsible BSI committee. Annotated drafts are not acceptable and will be rejected. All comments must be submitted, preferably electronically, to the Responsible Committee Secretary at the address given on the front cover. Comments should be compatible with Version 6.0 or Version Version 97 of Microsoft® Word for Windows™, if possible; otherwise comments in ASCII text format are acceptable. Any comments not submitted electronically should still adhere to these format requirements. All comments submitted should be presented as given in in the example below. Further information on submitting comments and how to obtain a blank electronic version of a comment form are available from the BSI web site at: http://www.bsigroup.com/en/Standards-and-Publications/Current-work/DPCs/

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DRAFT INTERNATIONAL STANDARD ISO/DIS 22477-5 ISO/TC 182/SC 182/SC 1

Secretariat: DIN

Voting begins on 2009-12-17

Voting terminates on 2010-05-17

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION

•

МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ

•

ORGANISATION INTERNATIONALE DE NORMALISATION NORMALISATION

Geotechnical investigation and testing — Testing of geotechnical structures — Part 5: Testing of anchorages Reconnaissance et essais géotechniques — Essais de structures géotechniques — Partie 5: Essai du tirant d'ancrage

ICS 93.020

This draft has been developed within the European Committee for Standardization (CEN), and processed under the CEN-lead mode CEN-lead mode of collaboration as defined in the Vienna Agreement. This draft is hereby submitted to the ISO member bodies and to the CEN member bodies for a parallel five-month enquiry. Should this draft be accepted, a final draft, established on the basis of comments received, will be submitted to a parallel two-month approval vote in ISO and formal vote i n CEN.

In accordance with the provisions of Council Resolution 15/1993 this document is circulated in the English language only. Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est distribué en version anglaise seulement. To expedite distribution, this document is circulated as received from the committee secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at publication stage. Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au Secrétariat central de l'ISO au stade de publication.

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© International Organization for Standardization, Standardization, 2009

ISO/DIS 22477-5

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© ISO 2009 – All rights reserved

ISO/DIS 22477-5

Contents

Page

Forew ord ........................................................................................................................................................... vi i Introduction ...................................................................................................................................................... viii 1

Scope ...................................................................................................................................................... 1

2

Normative referenc es ............................................................................................................................ 1

3 3.1 3.2

Terms, defi nit ion s and sy mbols .......................................................................................................... 2 Terms and definit ions ........................................................................................................................... 2 Symbols .................................................................................................................................................. 2

4 4.1 4.2 4.3 4.4 4.5 4.6

Equipment .............................................................................................................................................. 4 Test loading set -up ................................................................................................................................ 4 Reactio n sy st em .................................................................................................................................... 5 Loading devic e ...................................................................................................................................... 5 Load measu rement ................................................................................................................................ 6 Dis pl acement measurement ................................................................................................................. 6 Time and temperature measu rement .................................................................................................. 6

5 5.1 5.2 5.3 5.4

Test proc edur es ..................................................................................................................................... 7 General ................................................................................................................................................... 7 Method 1: Cyclic tensi on test with disp lacement measurement at peak load ................................ 7 Method 2: Cyclic tensio n test wit h loss of load measurement at peak load ................................... 7 Method 3: Step-lo aded maintain ed tension test ................................................................................ 7

6 6.1 6.2

Test repo rt .............................................................................................................................................. 7 Investigati on and suit abilit y test s ........................................................................................................ 7 Ac ceptance test ..................................................................................................................................... 8

Annex A.1 A.1.1 A.1.2 A.1.3 A.1.4 A.2 A.2.1 A.2.2 A.2.3 A.2.4 A.2.5 A.3 A.3.1 A.3.2 A.3.3 A.3.4

A (normative) Test Procedure: Meth od 1 .......................................................................................... 10 Investig ation test procedure .............................................................................................................. 10 Test anchors ........................................................................................................................................ 10 Time peri od between inst allation and t esting .................................................................................. 10 Test execution ..................................................................................................................................... 11 Test results .......................................................................................................................................... 14 Suitabil it y t est procedur e ................................................................................................................... 14 General ................................................................................................................................................. 14 Test anchor .......................................................................................................................................... 14 Time peri od between inst allation and t esting .................................................................................. 14 Test execution ..................................................................................................................................... 14 Test results .......................................................................................................................................... 17 Ac ceptance test procedur e ................................................................................................................ 17 General ................................................................................................................................................. 17 Time peri od between inst allation and t esting .................................................................................. 17 Test execution ..................................................................................................................................... 17 Test results .......................................................................................................................................... 19

Annex B.1 B.2 B.3

B (i nformativ e) Examples of t est reports : Method 1 ........................................................................ 20 Investig ati on test ................................................................................................................................. 21 Suitabil it y tes t ...................................................................................................................................... 22 Ac ceptance test ................................................................................................................................... 23

Annex C.1 C.1.1 C.1.2

C (nor mative) Test proc edur e: Meth od 2 .......................................................................................... 24 Investig ation test procedure .............................................................................................................. 24 General ................................................................................................................................................. 24 Test anchors ........................................................................................................................................ 24


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C.1.3 C.1.4 C.1.5 C.2 C.2.1 C.2.2 C.2.3 C.2.4 C.2.5 C.3 C.3.1 C.3.2 C.3.3 C.3.4

Time peri od betw een ins tall atio n and test ing ...................................................................................25 Test execut ion ......................................................................................................................................25 Test results ...........................................................................................................................................27 Suitabil it y test procedure ....................................................................................................................27 General ..................................................................................................................................................27 Test anchor ...........................................................................................................................................27 Time peri od betw een ins tall atio n and lo ading ..................................................................................28 Test execut ion ......................................................................................................................................28 Test results ...........................................................................................................................................30 Ac ceptance tes t procedur e.................................................................................................................30 General ..................................................................................................................................................30 Time b etween i nstall atio n and test ing ...............................................................................................31 Test execut ion ......................................................................................................................................31 Test results ...........................................................................................................................................33

Annex D.1 D.2 D.3

D (info rmative) Examples of t est reports : Method 2 ........................................................................34 Invest igati on test .................................................................................................................................35 Suitabil it y test ......................................................................................................................................36 Ac ceptance test ...................................................................................................................................37

Annex E.1 E.1.1 E.1.2 E.1.3 E.1.4 E.1.5 E.2 E.2.1 E.2.2 E.2.3 E.2.4 E.2.5 E.3 E.3.1 E.3.2 E.3.3 E.3.4

E (nor mative) Test proc edur e: Meth od 3 ...........................................................................................38 Invest igati on test procedure ...............................................................................................................38 General ..................................................................................................................................................38 Test anch ors ........................................................................................................................................38 Time peri od betw een ins tall atio n and test ing ...................................................................................39 Test execut ion ......................................................................................................................................39 Test resul ts ...........................................................................................................................................41 Suitabil it y test procedure ....................................................................................................................41 General ..................................................................................................................................................41 Test anchor ...........................................................................................................................................41 Time peri od betw een ins tall atio n and test ing ...................................................................................42 Test execut ion ......................................................................................................................................42 Test resul ts ...........................................................................................................................................44 Ac ceptance test procedur e.................................................................................................................44 General ..................................................................................................................................................44 Time peri od betw een ins tall atio n and test ing ...................................................................................45 Test execut ion ......................................................................................................................................45 Test resul ts ...........................................................................................................................................47

Annex F.1 F.2 F.3

F (in formati ve) Exampl es of t est reports : Method 3.........................................................................49 Invest igati on test .................................................................................................................................50 Suitabil it y test ......................................................................................................................................51 Ac ceptance test ...................................................................................................................................52

Annex G.1 G.2 G.3

G (info rmative) Guidance on allowable 1 (Method 1) and t est interpr etatio n ..............................53 Determin ation of ..............................................................................................................................53 Suitabil it y test ......................................................................................................................................54 Ac ceptance test ...................................................................................................................................54

Annex H.1 H.1.1 H.1.2 H.1.3 H.2 H.3

H (info rmati ve) Guidance on allowable k i and on test int erpretati on: Method 2 ...........................56 Permissi ble cumulative loss of load k l ..............................................................................................56 Investig ation test .................................................................................................................................56 Suitabilit y test ......................................................................................................................................56 Ac ceptance test ...................................................................................................................................56 Determination of the anchor critic al resistance R c ..........................................................................56 Determination of the anchor pull out resistance R a .........................................................................57

Annex I.1 I.1.1 I.1.2 I.2

I (in fo rmative) Guidance on allowable 3 and test int erpret ation: Metho d 3 ................................59 Determin ation of ..............................................................................................................................59 All owable value of 3 for suitabil it y test s ..........................................................................................59 All owable value of 3 for acceptance tests .......................................................................................60 Determin ation of the crit ical creep load P c .......................................................................................60

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ISO/DIS 22477-5

I.3

Determination of anchor pull out resistance R a ............................................................................... 61

Annex J.1 J.2 J.3

J (inf ormativ e) Evaluation of t he app arent tendon f ree len gth ....................................................... 63 General ................................................................................................................................................. 63 Determi nati on of fric ti on resist ance .................................................................................................. 63 Toleranc es ............................................................................................................................................ 64

Figures Figure 1 — Sketch of a ground anchor (details of anchor head and head protection omitted) ........................... 4 Figure 2 — Test loading set-up (example for an investigation test) ..................................................................... 5 Figure A.1 — Loading procedure – Investigation test method 1 ........................................................................ 12 Figure A.2 — Plot of increase of displacements vs. number of cycles .............................................................. 13 Figure A.3 — Loading procedure – Suitability test method 1 ............................................................................. 15 Figure A.4 — Loading procedure – Acceptance test method 1 ......................................................................... 18 Figure B.1 — Cyclic tension test (Method 1) – Example of investigation test report .........................................21 Figure B.2 — Cyclic tension test (Method 1) – Example of suitability test report .............................................. 22 Figure B.3 — Cyclic tension test (Method 1) – Example of acceptance test report ........................................... 23 Figure C.1 — Loading procedure – Investigation test method 2 ........................................................................ 26 Figure C.2 — Loading procedure – Suitability test method 2 (permanent anchorage) ...................................... 29 Figure C.3 — Loading procedure – Acceptance test method 2 (permanent anchorages) ................................ 32 Figure D.1 — Cyclic tension test (Method 2) – Example of investigation test report ......................................... 35 Figure D.2 — Cyclic tension test (Method 2) – Example of suitability test report .............................................. 36 Figure D.3 — Cyclic tension test (Method 2) – Example of acceptance test report ........................................... 37 Figure E.1 — Loading procedure – Investigation test method 3 ........................................................................ 40 Figure E.2 — Loading procedure – Suitability test method 3 ............................................................................ 43 Figure E.3 — Loading procedure – Acceptance test method 3 ......................................................................... 46 Figure F.1 — Maintained tension test (Method 3) – Example of investigation test report ................................. 50 Figure F.2 — Maintained tension test (Method 3) – Example of suitability test report....................................... 51 Figure F.3 — Maintained tension test (Method 3) – Example of acceptance test report ................................... 52 Figure G.1 — Time displacement plot for calculation the creep ratio

α 1 ............................................................53

Figure H.1 — Determination of the anchor critical resistance – Investigation test............................................. 57 Figure H.2 — Determination of the anchor pull out resistance – Investigation test ........................................... 58 Figure I.1 — Determination of the slope of the stabilization curve at constant load .......................................... 59


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ISO/DIS 22477-5

Figure I.2 — Determination of the anchor critical resistance – Investigation test.............................................. 61 Figure I.3 — Determination of the anchor pull out resistance – Investigation test – Method 3 ......................... 62 Figure J.1 — Estimate of elastic stiffness where there is significant friction ..................................................... 64

Tables Table A.1 — Loading procedure – Investigation test method 1 ........................................................................ 12 Table A.2 — Loading procedure – Suitability test method 1 ............................................................................. 16 Table A.3— Loading procedure – Acceptance test method 1 ........................................................................... 18 Table C.1 — Loading procedure – Investigation test method 2 ........................................................................ 26 Table C.2 — Loading procedure – Suitability test method 2 ............................................................................. 29 Table C.3 — Loading procedure – Acceptance test method 2 .......................................................................... 32 Table E.1 — Loading procedure – Investigation test method 3 ........................................................................ 40 Table E.2 — Loading procedure – Suitability test method 3 ............................................................................. 43 Table E.3 — Loading procedure without cycle – Acceptance test method 3 .................................................... 46 Table E.4 — Loading procedure with cycle – Acceptance test method 3 ......................................................... 46 Table G.1 — Suitability tests: observation times on allowable displacements or creep ratios at proof load P p 54 Table G.2 — Observation times and permissible displacements and creep ratios at the proof load P p of acceptance tests ......................................................................................................................................... 55 Table H.1 — Permissible cumulative loss of load k l .......................................................................................... 56

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Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 22477-5 was prepared by the European Committee for Standardization (CEN) Technical Committee CEN/TC 341, Geotechnical investigation and testing , in collaboration with Technical Committee ISO/TC 182, Geotechnics, Subcommittee SC 01, Geotechnical testing , in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement). ISO 22477 consists of the following parts, under preparation, under the general title Geotechnical investigation and testing — Testing of geotechnical structures: ⎯ Part 1: Pile load test by static axially loaded compression ⎯ Part 2: Pile load test by static axially loaded tension ⎯ Part 3: Pile load test by static transversally loaded tension ⎯ Part 4: Pile load test by dynamic axially loaded compression test ⎯ Part 5: Testing of anchorages ⎯ Part 6: Testing of nailing ⎯ Part 7: Testing of reinforced fill


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ISO/DIS 22477-5

Introduction Various in-situ tests may be carried out on ground anchors (Investigation test, Suitability test, Acceptance test) and different stressing procedures may be followed (method 1: cyclic tension test with displacement measurement at peak load; method 2: cyclic tension test with loss of load measurement at peak load; method 3: step-loaded maintained tension test) up to a proof tension or up to the ultimate soil-anchor resistance. The present document concerns method 1, method 2 and method 3.

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DRAFT INTERNATIONAL STANDARD

ISO/DIS 22477-5

Geotechnical investigation and testing — Testing of geotechnical structures — Part 5:

Testing of anchorages

1

Scope

(1) This Standard establishes specifications for the execution of tension load tests where an anchor grouted in the ground, as defined in EN 1997-1, is loaded by step (method 3) or in incremental cycles (methods 1 and 2) from a datum load to a maximum test load. The displacement of the anchor head is measured over a period of time at each step (method 3) or at maximum load in each incremental cycle (method 1). The loss of load is measured over a period of time, at maximum load after lock off, in each incremental cycle (method 2). (2) This standard provides specifications for three types of tension tests: investigation tests, suitability tests and acceptance tests. These tests are defined by EN 1997-1 as: - tests aimed at estimating the pull-out resistance (investigation tests), NOTE 1 From these tests, other information, such as the critical creep load, may be obtained.

- tests aimed at checking the suitability of the execution method in the actual conditions of the construction site (suitability tests), NOTE 2 Normally this test is done on a working anchor with a proof load equal to that used for acceptance test. If higher load is applied, this test must be considered as an investigation test and the anchor cannot be used as working anchor.

- Tests aimed at checking that each anchor will resist at least t he design load (acceptance tests). (3) For the different types of tests only one method shall be used in each project. The method must be prescribed in the project specifications. (4) The standard provides specifications for the experimental devices, the measurement apparatus, the test procedures, the definition and the presentation of the test results and the content of records. (5) Guidance is given on the determination of the measured value of the pull out resistance R a of an anchor on the basis of investigation tests and for checking of the displacement behaviour of an anchor on the basis of suitability tests and acceptance tests. (6) This standard shall be used in conjunction with EN 1997-1 and EN 1537.

2

Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1537, Execution of special geotechnical works – Ground anchors EN 1997-1, Eurocode 7: Geotechnical design – Part 1: General rules EN 1993 or EN 1992, for rules for tension of pre-stress steel.


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ISO/DIS 22477-5

3

Terms, definitions and symbols

3.1 Terms and definitio ns For the purposes of this document, the terms and definitions given in EN 1997-1 and EN 1537 and the following apply. 3.1.1 preliminary anchor anchor which is installed before the commencement of the anchoring works for the purpose of establishing the suitability of the chosen type of anchors and for confirming its design, dimensions and tension resistance. 3.1.2 working anchor anchor that is part of a structure 3.1.3 estimated anchor pull out resist ance ultimate resistance of the ground-anchor interaction determined on the basis of comparable experience or numerical calculation before the test 3.1.4 anchor pull-out resistance limit pull out force of an anchor 3.1.5 critic al creep load load corresponding to the end of the first pseudo linear part of the “ α versus load diagram” 3.1.6 anchor tendon r esistance ultimate structural resistance of an anchor tendon.

3.2

Symbols

At

Cross sectional area of anchor tendon

E t

Elastic apparent modulus of anchor tendon

f

Friction loss as a percentage of Pp

k l

Load loss

Lapp

Apparent tendon free length

Le

External length of tendon measured at P a from the tendon anchorage in the anchor head to the anchorage point in the stressing jack

Lfixed

Fixed anchor length

Lfree

Free anchor length

Lt

Tendon length

Ltb

Tendon bond length

Ltf

Tendon free length

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ISO/DIS 22477-5

P

Load on an anchor

P a

Datum load

P c

Critical creep load

P o

Anchor lock-off load

P p

Proof load

P u

Anchor ultimate load determined in an Investigation test

R a

Anchor pull-out resistance

R e

Estimated anchor pull-out resistance

s

Anchor head displacement

so

Anchor head displacement under datum load P a

t

Time from application of load increment or load lock-off

α 1

Slope of “creep displacement vs. decimal logarithm of time” plot from method 1

α 3

Slope of “creep displacement vs. decimal logarithm of time” plot from method 3

∆P

Difference between proof load and anchor datum load

∆P f

Friction loss

∆s

Measured extension of anchor tendon under load increment


∆P

3

ISO/DIS 22477-5

Key 1

Anchorage point at jack during stressing

2

Anchorage point at anchor head in service

3

Bearing plate

4

Load transfer block

5

Structural element

6

Soil/rock

7

Borehole

8

Debonding sleeve

9

Tendon

10 Grout body

Figure 1 — Sketch of a ground anchor (details of anchor head and head protection omitted)

4

Equipment

4.1 Test loadi ng set-up (1) The test loading set-up comprises of a stressing device, displacement and load monitoring devices, a reaction system, associated locking nuts, extension pieces and packing, etc. NOTE An example of an investigation test loading set-up is given in Figure 2. Where possible it is better to measure the load between the loading device and the bearing plate to avoid the determination of the friction in the jack.

(2) The test loading system shall be designed to operate safely up to the maximum test load (proof load P p).

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ISO/DIS 22477-5

2

3 4

1 5

6

Key 1

Displacement monitoring

2

Load monitoring

3

Stressing device

4

Reaction system

5

Tendon

6

Hydraulic system

Figure 2 — Test loading set-up (example for an investigation test)

4.2 Reacti on sys tem (1) The reaction system shall be designed to have a structural resistance at least equal to the maximum test load (P p), according to the relevant EN standards. (2) The reaction system should be designed to avoid excessive deformation at the maximum test load. In some cases (for example anchored sheet-pile walls) this is not possible due to soil conditions or staged construction. In that case extra measurements should be performed to determine the displacement of the structure itself during t esting. (3) The reaction system should be designed so as not to affect the test results, nor to impose loads in excess of the safe bearing capacity of the retaining structure.

4.3 Loadi ng devic e (1) The stressing device, normally a hydraulically operated jack, shall have a capacity at least equal to the maximum test load. (2) The extension of the jack should be sufficient to avoid reseating during the test. (3) The extension of the jack should be greater than the sum of the displacement of the anchor head under the maximum load and the displacement of the reaction system. In cases where a single jack cannot provide the necessary extension, such as for very long anchors, special equipment (e.g. multiple jacks) shall be used.


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ISO/DIS 22477-5

(4) The equipment (hydraulic jack, pumping unit, etc.) shall be capable of safely tensioning the tendon smoothly and axially, in accordance with the test procedure. The load shall not be applied or released quicker than 10 kN per second (see Annexes A, C and E test procedures). (5) Stressing equipment for bar and strand tendons should tension the complete tendon as a single unit. (6) Stressing equipment which tensions individual strands not simultaneously should be provided with or be supplemented by measuring devices which establish the total load in the multiple strands at any time during testing. Alternatively accurate lift-off checks should be undertaken.

4.4 Load measurement (1) The load P shall be measured with an appropriate device. (2) The load may be measured either indirectly (e.g. by means of a calibrated pressure gauge, monitoring the hydraulic pressure in the stressing device) or directly (e.g. by the use of a load cell). (3) The allowable minimum accuracy of the measured load shall be the larger values of: ⎯ 2 % of the measured value or 10 kN, for methods 1 and 3; ⎯ 0,5 % of the measured value or 5 kN, for method 2.

Where relevant, the calibration test shall include the stressing device. (4) Pressure gauges and load cells used to measure the load shall be calibrated within 1 year before carrying out the test. The calibration certificates shall be made available for inspection on site at all times.

4.5 Displ acement measurement (1) The displacements of the tendon head shall be measured with an appropriate device. The support for the displacement gauges shall be remote from the stressing device and reaction system and be sufficiently rigid so as not to be influenced by climatic effects, or background vibrations. (2) The measurement accuracy on the displacement shall be the larger values of 0,1 mm or 1 % of the measured value. (3) The displacement gauges used shall be calibrated within 1 year before carrying out the test. (4) Displacement gauges should be capable of monitoring the extension of the anchor head, throughout the test, without the need for reseating. (5) Where relevant, for example when the reaction system cannot be designed to avoid excessive deformation, the displacement of the reaction system should also be measured with an appropriate device, throughout the test.

4.6 Time and temperatu re measurement (1) The accuracy of the measured time shall be equal or less than 1 s. (2) The accuracy of the measured temperature shall equal or be less than 1 °C.

6


ISO/DIS 22477-5

5

Test proc edures

5.1 General For the different types of tests only one method shall be used in each project. The method must be chosen in the project specifications. NOTE

In some countries the use of a particular method is compulsory.

5.2 Method 1: Cyclic tensio n test with displacement measurement at peak load The test procedure for Method 1 shall be carried out according to Annex A. Examples of investigation, suitability and acceptance test reports are given in Annex B.

5.3 Method 2: Cyclic tensio n test with loss of load measurement at peak load The test procedure for Method 2 shall be carried out according to Annex C. Examples of investigation, suitability and acceptance test reports are given in Annex D.

5.4 Method 3: Step-loaded maint ained tensi on test The test procedure for Method 3 shall be carried out according to Annex E. Examples of investigation, suitability and acceptance test reports are given in Annex F.

6

Test report

6.1 Investigation and suit ability tests (1) The test report shall at least include: a)

reference to all relevant standards;

b)

the following specifications concerning the test anchor:

c)

d)

1)

location and type of anchor;

2)

date of installation;

3)

observations related to the installation of the anchor, likely to have an influence on the test results;

4)

geometrical data of the anchor and mechanical properties of the anchor material;

5)

level of its top, its base and of the ground around it;

6)

estimated anchor resistance from calculations.

the following factors concerning soil conditions: 1)

location of the closest geotechnical investigation profiles;

2)

reference to the site investigation report.

the following factors concerning the anchor test: 1)

reference of the organisation which has carried out the test;


7

ISO/DIS 22477-5

e)

2)

date of the test;

3)

value of the prescribed maximum load;

4)

characteristics of the loading system;

5)

description of all monitoring systems and their components;

6)

sketch of the instrumentation of the test anchor;

7)

observations related to the execution of the test, likely to have an influence on the results.

if relevant, the following test results based on collected data: 1)

plot of “anchor head displacement versus anchor load” at the end of each load step;

2)

plot of “anchor head displacement versus time” for each load step;

3)

plot of “α1 or α3 versus anchor load” ;

4)

anchor critical resistance Rc;

5)

anchor pull-out resistance R a;

6)

plot of “load-loss versus time” for each load step and after lock-off;

7)

plot of “kl versus anchor load” ;

8)

plot of “elastic and plastic displacements versus anchor load”;

9)

plot of “increase of displacements versus number of cycles”.

NOTE Examples of a test report are given in Annexes B.1, D.1 and F.1 for the investigation test and in Annexes B.2, D.2 and F.2 for the suitability test.

(2) Tables of numerical values of the collected data shall be provided in the Annexes of the test report.

6.2 Acc eptance test (1) The test report shall at least include: a)

reference to all relevant standards;

b)

the following specifications concerning the test anchor:

c)

1)

location and type of anchor;

2)

date of installation;

3)

observations related to the installation of the anchor, likely to have an influence on the test results;

4)

geometrical data of the anchor and mechanical properties of the anchor material;

5)

level of its top, its base and of the ground around it;

the following factors concerning the anchor test: 1)

8

reference of the organisation which has carried out the test;


ISO/DIS 22477-5

d)

2)

date of the test;

3)

value of the prescribed maximum load;

if relevant, the following test results based on collected data : 1)

plot of “anchor head displacement versus anchor load”;

2)

plot of “anchor head displacement versus time” at the proof load;

3)

anchor head displacement at the proof load;

4)

α 1 or α 3 value

5)

plot of “load-loss versus time” for each load step and after lock-off;

6)

plot of “k l versus anchor load” ;

7)

apparent tendon free length.

NOTE

at the proof load;

Examples of test report are given in Annexes B.3, D.3 and F.3.


9

ISO/DIS 22477-5

An nex A (normative) Test Procedure: Method 1

A.1 Inv est igat io n t est pr oc edu re (1) An investigation test according to method 1 is a test in which an axial load is applied incrementally in at least six cycles to a ground anchor up to a proof load P p, which is designed to reach failure of the soil-anchor bond or interface. At the maximum load of each cycle the load is maintained constant during a specified period of time. The test involves measurement of tendon head displacement versus applied load and, for each load step, measurement of tendon head displacement versus time.

A.1.1 Test ancho rs (1) Investigation tests shall be carried out on anchors which are not part of an actual structure, installed prior to the installation of working anchors. A.1.1.1

Test lo cation

(1) Soil conditions at the test location shall be representative for the soil conditions of working anchors. (2) The results of the site investigation shall be considered when selecting a test anchor location. A.1.1.2

Exec ution

(1) Test anchors shall be representative of working anchors. (2) Test anchors shall be installed using the same installation procedures as working anchors. (3) The method used for the installation of test anchors shall be fully documented. NOTE Records should be made of relevant aspects of the installation including: installation procedure, soil and hydro-geological conditions and if applicable, results of the tests and checks carried out on the anchor material and any difficulties encountered during execution.

(4) Test anchors should have the same inclination as working anchors. (5) The anchor bond length of a test anchor should be representative of the anchor bond length of a working anchor. (6) Test anchors with a shorter bond length than working anchors may be considered, provided that this length is not less than 5 m. (7) Test anchors and any extension pieces required for testing shall be designed to satisfy the condition on the load being lower than the yield load of the material (EN1992, EN1993 or standards for other materials, where relevant).

A.1.2 Tim e perio d b etw een ins tal lat io n an d t est in g (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved.

10


ISO/DIS 22477-5

NOTE

Depending on the materials used, this usually takes one week.

A.1.3 Test exec ut io n A.1.3.1

Test preparat io n

(1) Prior to commencement of the test, the preparation shall at least include: a) installation of measurement devices and checking its normal and safe functioning; b)

establishing a perimeter of safety around the test anchor;

c)

installation of the stressing system and checking its normal and safe functioning (e.g. it shall be checked that the stressing device is in the axis of the test anchor).

(2) The displacement reference system shall be located in such a way that it is not affected by any displacement of the reaction system and it shall be protected against climatic effects. A.1.3.2

Maximum t est load

(1) The maximum test load P p shall be defined prior to the test in accordance with EN 1997-1. A.1.3.3

Datum load

(1) A datum load P a shall be applied to minimise movement of the anchor test set-up on initial loading. Usually, this datum load is taken equal to the minimum load between 50 kN and 10% of P p. A.1.3.4

Loading procedure

The anchor should be loaded from the datum load P a to the maximum test load in a minimum of six cycles. The maximum load for each cycle is specified in Figure A.1 and Table A.1. In each cycle, the maximum load shall be reached in stages. The loading stages shall be P a - 0,40 Pp – 0,55 P p - 0,70 P p - 0,80 P p 0,90 P p and 1,00 P p, as shown in Figure A.1. The displacements of the outer end of the anchor shall be registered at each loading stage. The minimum observation times shall be 1 minute, except for the maximum load of each cycle, which shall be kept constant at minimum during the observation times indicated in Table A.1. Subsequently, the anchor shall be unloaded to the datum load using the same loading stages. The observation times for unloading stages shall be 1 minute. The observation times for loading stages reached for the first time shall be extended if the creep ratio α 1 cannot be clearly determined. NOTE

Guidance on the determination of α 1 is given in the informative Annex G.


11

ISO/DIS 22477-5

100 90 80 70

p P e g a t n e c r e P

60 50 40 30 20 10 0 0

60

120

180

240

Time [min]

Figure A.1 — Loading procedure – Investigation test method 1 Table A.1 — Loading procedure – Investigation test method 1 Cycle

Maximum load

1 2 3 4 5 6

0,40 Pp 0,55 Pp 0,70 Pp 0,80 Pp 0,90 Pp 1,00 Pp

Minimum observation time (min) at maximum load Non cohesive soil and rock Cohesive soil 15 15 15 15 30 60 30 60 30 60 60 180

The measured pull-out resistance R a of an anchor is reached when the creep ratio α1 exceeds the value of 2,0 mm. The characteristic pull-out resistance R ak is defined as the smallest value R a, registered for one of the tested anchors. In cases where the creep ratio α1 does not exceed 2,0 mm during the test, the characteristic measured pullout resistance R ak shall be defined as the maximum test load. A.1.3.5

Measur ement and ch ecks

(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing Investigation tests: a) if necessary, after application of the datum load P a , the initial displacement so shall be recorded; b)

during the stressing stage, at each load step, if necessary, the load and the anchor head-displacement shall at least be recorded at the successive monitoring times (in minutes) as indicated below: 1→2→3→4→5→7→10→15→20→30→45→60→90→120→150→180.

12


ISO/DIS 22477-5

NOTE Where relevant (e.g extended observation) the control of the load and of the anchor head-displacement should be performed with a periodicity less than the successive monitoring times indicated above.

c)

during the de-stressing stage, the load and the anchor head-displacement shall be recorded at least at the end of each step.

d)

where relevant, the displacement of the reaction system shall be recorded at least at the end of each load step.

(3) At the highest load of each cycle, the value of

α 1 shall

be checked.

(4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured. (6) Group effects. Tests on anchor groups are required in cases where centre line distances of grout bodies of anchors with characteristic load P k > 700 kN are less than 1,5 m. For this case, simultaneous suitability testing is to be carried out on three adjacent anchors. (7) Oscillating loads. A test with oscillating loads should be carried out on permanent anchors subsequent to suitability testing if these anchors - are subjected to oscillating loads exceeding the lock-off load and - the fixed anchor lengths are in ground critical to alternating loads (e.g. saturated fine sands). Example: such situation can exist, e.g. for the uplift anchorages of sluices in cases where the anchors are not locked-off to the total working load. For the test, the anchor shall be subjected 20 times to oscillating load cycles between an upper load of P k and a lower load of 0,5 P k. The displacements shall be registered at least after each fifth cycle. Subsequently, the anchor shall be unloaded to the initial load P a and the permanent displacements resulting from the oscillating load cycles shall be determined. The displacements per cycle should decrease with the number of cycles, both at the upper and the lower loads. The curve displacement vs. number of cycles should asymptotically approach a horizontal line (Figure A.2). The result of the oscillating test shall be approved by the client’s technical representative.

upper load Pk ] m m [ s t n e m e c a l p s i d f o e s a e r c n i

lower load Pk

number of cycles [n]

Figure A.2 — Plot of increase of displacements vs. number of cycles


13

ISO/DIS 22477-5

A.1.4 Test res ul ts (1) Based on the collected data, at least the following relationships shall be plotted: ⎯ plot of “anchor head displacement versus anchor load” at the end of each load step; ⎯ plot of “anchor head displacement versus time” at the highest load of each cycle; ⎯ plot of “α1 versus anchor load” ; ⎯ plot of “anchor head displacement versus load cycles” (if necessary).

(2) Based on the collected data, at least the following parameters shall be determined: ⎯ measured anchor pull-out resistance R a (Informative Annex I); ⎯ calculated tendon apparent free length L app (Informative Annex J).

A.2 Sui tab il it y t est pr oc edu re A.2.1 General (1) A suitability test according to method 1 is a test in which an axial load is applied incrementally in at least five cycles to a ground anchor up to a proof load P p to confirm that a particular anchor design will be adequate in particular ground conditions. At the maximum load of each cycle the load is maintained constant during a specified period. The test involves measurement of tendon head displacement versus applied load and, for each load step, measurement of tendon head displacement versus time.

A.2.2 Test ancho r (1) Suitability tests may be performed on working anchors. A.2.2.1

Exec ution

(1) The method used for the installation of the test anchor shall be fully documented. NOTE Records should be made of relevant aspects of the installation including: installation procedure, soil- and hydro-geological conditions and if applicable, results of the tests and checks carried out on the anchor material and any difficulties encountered during execution.

(2) Test anchors and any extension pieces required for testing shall be designed to satisfy the condition on the load being lower than the yield load of the material (EN1992, EN1993 or standards for other materials, where relevant).

A.2.3 Tim e perio d b etw een ins tal lat io n an d t est in g (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE


A.2.4 Test execut io n A.2.4.1

Test preparat ion

(1) Prior to commencement of the test, the preparation shall at least include :

14


ISO/DIS 22477-5

a)

installation of measurement devices and checking their normal and safe functioning;

b)


c)


(2) The displacement reference system shall be located in such a way that it is not affected by any displacement of the reaction system and it shall be protected against climatic effects. A.2.4.2

Proof load

(1) The proof load P p shall be defined prior to the test in accordance with EN 1997-1. A.2.4.3

Datum Load


Loading procedure

(1) The loading procedure shown in Figure A.3 and Table A.2 should be followed for conducting suitability tests. Each anchor should be loaded to proof load within a minimum of five cycles. (2) The load shall not be applied or released quicker than 10 kN per second . (3) A loading stage may be stopped when α1 becomes larger than 2 mm. NOTE

Guidance on the determination of the slope α1 is given in the informative Annex G.

100 90 80 70 60

p ) P % ( 50

d a o 40 L 30 20 10 0 0

60

120

180

240

Time (min)

Figure A.3 — Loading procedure – Suitability test method 1


15

ISO/DIS 22477-5

Table A.2 — Loading procedure – Suitability test method 1

Cycle 1 2 3 4 5

A.2.4.5

Maximum load 0,40 0,55 0,70 0,85 1,00

Pp Pp Pp Pp Pp

Minimum observation time (min) at maximum load Temporary anchor Permanent anchor Non cohesive Cohesive soil Non cohesive Cohesive soil soil and rock soil and rock 1 1 15 15 1 1 15 15 5 5 30 60 5 5 30 60 30 60 60 180


(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing suitability tests: The displacements of the outer end of the anchor shall be registered at each loading stage. After a loading stage is reached for the first time, the load shall be kept constant at minimum for the observation times indicated in Table A.2 and shall stepwise be reduced to the initial load P a. Subsequently, load shall be increased stepwise to the maximum load of the next loading cycles. The observation time at unloading stages is 1 minute. During the observation time, the load shall be kept constant and the displacements shall be registered (e.g. at 1, 2, 3, 5, 10, 15, 20, 30, 45, 60 min.) and be plotted in semi-logarithmic scale (see Figure G.2). The observation times indicated in Table A.2 shall be extended if one of the following applies: a) increase of displacements ∆s ≥ 0,5 mm for − temporary anchors in non-cohesive soils and rock: between 10 and 30 minutes, − temporary anchors in cohesive soils:

between 20 and 60 minutes,

− permanent anchors in non-cohesive soils and rock:


− permanent anchors in cohesive soils:


or b) the slope of the plot “logarithm of time vs. displacement” (see Figure G.2) increases. For cases a) and b), the observation times shall be extended until the creep ratio derived from a linear part at the end of the curve time vs. displacement can be determined clearly. For permanent anchors, the observation time inclusive of any extension shall be minimum 120 minutes in noncohesive soils or rock and minimum 720 minutes in cohesive soils, respectively. (3) At the highest load of each cycle, the value of

1 shall

be checked.

(4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured. (6) Group effects: if necessary see A.1.4.5 (6) (7) Oscillating loads: if necessary see A.1.4.5 (7)

16


ISO/DIS 22477-5

A.2.5 Test res ul ts A.2.5.1

General

(1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “anchor head displacement versus anchor load” at the end of each load cycle; ⎯ plot of “anchor head displacement versus time” at the maximum load of each cycle; ⎯ plot of “α1 versus anchor load” ; ⎯ plot of “displacement versus load” for all cycles.

(2) Based on the collected data, at least the following parameters shall be determined: ⎯ anchor head displacement at the proof load; ⎯ α1 value at the proof load; ⎯ calculated tendon apparent free length L app (Informative Annex J).

A.3 Ac cep tan ce t est pr oc edure A.3.1 General (1) An acceptance test according to method 1 is a test in which an axial load is applied incrementally in at least 5 steps to a ground anchor up to a proof load P p to confirm that a particular anchor meets the design requirements. At the maximum load of the cycle the load is maintained constant during a specified period. The test involves measurement of tendon head displacement versus applied load and, for each load step, measurement of tendon head displacement versus time. NOTE

Acceptance tests are compulsory for all grouted anchors

A.3.2 Tim e perio d b etw een ins tal lat io n an d t est in g (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE


A.3.3 Test exec ut io n A.3.3.1

Test preparat io n

(1) Prior to commencement of the test, the preparation shall at least include: a)

installation of measurement devices and checking their normal and safe functioning;

b)


c)


(2) The displacement reference system shall be located in such a way that it is not affected by any displacement of the reaction system and it shall be protected against climatic effects.


17

ISO/DIS 22477-5

A.3.3.2

Proof lo ad

(1) The proof load P p shall be defined prior to the test in accordance with EN 1997-1. A.3.3.3

Datum Load


Loading proc edure

(1) From the initial load P a, the anchors shall be loaded stepwise up to the proof load (Figure A.4) and be subsequently unloaded to the initial load P p. The observation times at each loading step are indicated in Table A.3. The displacement of the outer end of the anchor shall be registered for each loading step. (2) The load shall not be applied or released quicker than 10 kN per second . (3) At proof load, the value of

α 1 shall

be checked.

(4) For pre-stressed anchors, where there is significant friction in the free tendon length, a partial cycle may be performed to determine the no-friction curve to be able to calculate the apparent tendon free length more accurately (see also A.3.3.5).

100 90 80 70 ) p 60 P % ( d 50 a o L 40

30 20 10 0 0

5

10

15

20

25

Time (min)

Figure A.4 — Loading procedure – Acceptance test method 1 Table A.3— Loading pro cedure – Acceptance test method 1 Load step 1 2 3 4 6

18

Maximum load 0,40 Pp 0,55 Pp 0,70 Pp 0,85 Pp 1,00 Pp

Minimum observation time (min) at maximum load Non cohesive soil and rock Cohesive soil 1 1 1 1 1 1 1 1 5 15


ISO/DIS 22477-5

A.3.3.5


(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing acceptance tests: a) The proof load shall be kept for at least for 5 minutes for anchors in non-cohesive soils and rock or at least for 15 minutes in cohesive soils, respectively. The displacements and their variations shall be recorded during this time, e.g. after 1, 2, 3, 5, 10 and 15 minutes. The minimum observation times (Table A.3) shall be extended if the displacements exceed the permissible values. Then the observation time shall be prolonged until the creep ratio α1 can be determined clearly. b) where relevant, the displacement of the reaction system shall be recorded at least at the end of each load step. (3) At proof load, the value of α1 shall be checked. (4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured.

A.3.4 Test res ul ts (1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “anchor head displacement versus anchor load”; ⎯ plot of “anchor head displacement versus time” at the proof load.

(2) Based on the collected data, at least the following characteristics shall be determined: ⎯ anchor head displacement at the proof load; ⎯ α1 value at proof load.

(3) The apparent tendon free length should be calculated (informative Annex J).


19

ISO/DIS 22477-5

An nex B (informative) Examples of t est reports : Metho d 1

20


ISO/DIS 22477-5

B.1 Investigation test METHOD 1 – CYCLIC ANCHOR TEST

INVESTIGATION TEST

Organism : TENDON CHARACTERISTICS Tendon free length L tf (m) : Tendon bond length L tb (m) : Extension length Le (m) : Inclination β (deg) : 2 Section At (cm ) : Modulus Et (MPa) :

Site : Location reference : xxxxx

Reference : D xxxxx Installation : xx/xx/xxxx

P β

Le Ltf

BOND CHARACTERISTICS Anchor length Lfixed (m) : 2 Tool diameter A (cm ) : CYCLE NUMBER LOAD (kN) F a or %P P s (mm) t = 1 minute s (mm) t = 5 minutes s (mm) t = 15 minutes

Ltb

0 F a

1 40

-

α1 (mm)

TEST MEASUREMENT 2 3 4 55 F a 70 F a 80 F a

F a -

-

Date of the test : Observations :

-

5 90

-

6 F a

100

F a

-

-

-

-

Operators :

100

150

90 80

125

70

) p P 60 % ( 50 d a o 40 L

100 ) m m ( s

30

75 50

20

25

10 0 0

60

120

240

180

0

Time (min)

150

Time (min)

100

4

) m m3 (

100 75

1

α

2

50

1

25 0 0

10

5

125 ) m m ( s

1

Pa 20

40 60 Load (% of P p)

TEST RESULTS Anchor pull out resistance:

80

Ra (kN) = Pu =

100

0 0

Pa 20

40 60 Load (% of Pp)

80 Pu

100

Calculated tendon apparent free length: L app =

Figure B.1 — Cyclic tension test (Method 1) – Example of investigation test report


21

ISO/DIS 22477-5

B.2 Suitability test METHOD 1 – CYCLIC ANCHOR TEST

SUITABIL ITY TEST




P β

Le Ltf

BOND CHARACTERISTICS Anchor length Lfixed (m) : 2 Tool diameter A (cm ) : CYCLE NUMBER LOAD (kN) Pa or %Pp s (mm) t = 1 minute s (mm) t = 5 minutes s (mm) t = 15 minutes or …

Ltb

0 P a

1 40

-

α1 (mm)

TEST MEASUREMENT 2 3 4 55 70 85 P a P a P a

P a -

-

Date of the test : Observations :

-

-

100

-

-

-

-

-

-

P a

-

Operators :

100

150

90

125

80 70

100

p ) P 60 % ( 50 d a o 40 L

) m m ( s

30 20

75 50 25

10 0

5

0

60

120

180

0

240

1

10

Time (min)

150

Time (min)

100

5

125 4

) m m3 (

100 ) m m ( s

75

1

α

50 25 0 0

max α1

2 1

Pa 20

40 60 80 Load (% of P p)

TEST RESULTS Anchor head displacement at Pp :

sp (mm) =

100

0 0

α1Pp (mm)

Pa

α1 value at Pp :

20

40 60 Load (% of P p)

80

Pp 100

α1Pp (mm) =

Calculated tendon apparent free length: L app = Figure B.2 — Cyclic tension test (Method 1) – Example of suitability test report

22


ISO/DIS 22477-5

B.3 Acceptance test METHOD 1 – CYCLIC ANCHOR TEST

ACCEPTANCE TEST




P β

Le Ltf

BOND CHARACTERISTICS Anchor length Lfixed (m) : 2 Tool diameter A (cm ) : LOAD STEP NUMBER LOAD (kN) Pa or %Pp s (mm) t = 1 minute s (mm) t = 5 minutes

Ltb

0 Pa

1 40

1 55

2 70

-

-

-

-

α1 (mm) Date of the test :

-

-

TEST MEASUREMENT 3 4 85 100 -

-

-

-

-

-

-

-

-

Operators :

Observations : 100

150

90

) 125 m m 100 ( t n e 75 m e c a 50 l p s i D 25

80 70 ) p 60 P % 50 ( d a 40 o L

30 20

10 0 0

5

10

15

20

25

Time (min)

Load step 4

0 1

Time (min)

10

125 100 p

75

P t a ) m 50 m ( s 25

0 0

20

40

60

80

100

Load (% of Pp)

TEST RESULTS Anchor head displacement at Pp : sp (mm) = Calculated tendon apparent free length: L app =

α1 value at Pp :

α1Sp (mm) =

Figure B.3 — Cyclic tension test (Method 1) – Example of acceptance test report


23

ISO/DIS 22477-5

An n ex C (normative) Test Test p roc edure: Metho Metho d 2

C.1 C.1

Investigatio n test pro cedure

C.1.1 General (1) An investigation test according to method 2 is a test in which an axial load is applied incrementally in at least seven cycles to a ground anchor up to a proof load P p, which is determined to check the resistance of the interaction soil-anchor or the quality and safety of the design in relation to ground conditions. At the highest load of each cycle, the anchor head displacement relative to the structure is held constant. The test involves measurement of load loss, after lock-off, during a specified period (the anchor head is fixed against a load cell or an inactive jack).

C.1.2 Test anchors (1) Investigation tests shall be carried out on anchors which are not part of an actual structure, installed prior to the installation of working anchors. C.1.2. C.1.2.1 1

Test loc ation

(1) Soil conditions at the test location shall be representative for the soil conditions of working anchors. (2) The results of the site investigation shall be considered when selecting a test anchor location. C.1.2.2

Execution

(1) Test anchors shall be representative of working anchors. (2) Test anchors shall be installed using the same installation procedures as working anchors. (3) The method used for the installation of test anchors shall be fully documented. (3bis) Records should be made of relevant aspects of the installation including: installation procedure, procedure, soil and hydro-geological conditions and if applicable, results of the tests and checks carried out on the anchor material and any difficulties encountered during execution. (4) Test anchors should have the same inclination as working anchors. (5) The anchor bond length of a test anchor should be representative of the anchor bond length of a working anchor. (6) Test anchors with a shorter bond length as working anchors may be considered, provided that this length is not less than 5 m. (7) Test anchors and any extension pieces required for testing shall be designed to satisfy the condition on the load being lower than the yield load of the material (EN1992, EN1993 or standards for other materials, where relevant).

24


ISO/DIS 22477-5

C.1. C.1.3 3 Time period period between installation and testing (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE


C.1.4 Test execution C.1.4.1 C.1.4.1

Test preparat ion io n

(1) Prior to commencement of the test, the preparation shall at least include: a) installation of measurement devices and checking their normal and safe functioning; b) establishing a perimeter of safety around the test anchor; c) installation of the stressing system and checking its normal and safe functioning (e.g. it shall be checked that the stressing device is in the axis of t he test anchor). (2) The displacement reference system shall be located in such a way that it is not affected by any displacement displacement of the reaction system and it shall be protected against against climatic effects. C.1.4. C.1.4.2 2

Maximum test load

(1) The maximum test load P p shall be defined prior to t he test. C.1.4.3 C.1.4.3

Datum Load

(1) A datum load P a shall be applied to minimise movement of the anchor test set-up on initial loading. Usually, this datum load is taken equal to the minimum load between 50 kN and 10% of P p. C.1.4. C.1.4.4 4

Loading proc edure

(1) The loading procedure shown in Figure C.1 and Table C.1 should be followed for conducting Investigation tests. Where appropriate, the final load cycle should be repeated to provide a measured check on loaddisplacement behaviour and reproducibility. (2) For ground conditions conditions where previous previous anchoring anchoring knowledge knowledge is available, it is allowed allowed to load the anchorage up to 70%P p in the first cycle and to increase the load increment to 15%P p (10 – 25 – 40 – 55 - 70 nd rd – 50 – 25 – 10 %Pp). The load steps for 2 and 3 cycles may be adjusted to 10 – 44 – 62,5 – 75 – 87,5 – 100 – 62,5 – 44 %P p. (3) At PP, after 5000 min observation period (3 days), if the cumulative load loss, after allowing for temperature, structural movements and relaxation of the tendon, exceeds the allowable value or if the load loss has not attained a constant value, the test should be extended by monitoring at 7 days interval for a period up to 30 days or until the load becomes constant. NOTE

Guidance on the permissible cumulative loss of load kl is given in the informative Annex H (Table H1).

(4) If the determination of the anchor pull out resistance is needed, the load cycling of the ground anchor should be continued, when possible, after P P, to determine the anchor pull out load P u. (5) The load shall not be applied or released quicker than 10 kN per second .


25

ISO/DIS 22477-5

Load [% P P] 100

5000 or 15000 or 50000 min

90

15 min

80

15 min

70 15 min 60 15 min 50 15 min

40

30 15 min 20

10

0 0

Time [min]

Figure C.1 — Loading procedure – Investigation test method 2 Table C.1 — Loading procedure – Investigation test method 2 Minimum period of observation in minutes Test method 2

Load levels %P p

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Cycle 6

Cycles 7 and 8

10

10 25 31 37,5 25 12,5 10

10 37,5 44 50 37,5 17,5 10

10 50 56 62,5 50 25 10

10 62,5 69 75 50 25 10

10 75 81 87,5 62,5 37,5 10

10 81,5 94 100 62,5 37,5 10

17,5 25 17,5 10

1 1 1 15 1 1 1

NOTE It is recommended that load-displacement results should be plotted as the test proceeds. In this way it should be possible to observe trends and, in particular, the yield of the fixed anchor as failure approaches.

C.1.4.5 C.1.4.5

Measurement and checks ch ecks

(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing investigation tests: a)

26

if necessary, necessary, after after application application of the the datum datum load P a , the initial displacement s o shall be recorded;


ISO/DIS 22477-5

b)

during the stressing stage, at the highest load of each cycle and after lock-off, the value of the load loss k l at the anchor head shall at least be recorded at the following times (in minutes), depending on the duration of the load application : 0→5→15→50→150→1500 (1 day)

→5000

(3 days)

→15000

(10 days)

NOTE Where relevant (e.g extended observation) the control of the load loss should be performed with a periodicity less than the successive monitoring times indicated above.

c) where relevant, the displacement of the reaction system shall be recorded at least at the end of each load step. (3) Load-time data should be monitored commencing at loads not greater than 70% P p. (4) At the highest load of each cycle, the value of k l shall be checked, according to table H.1 (Annex H). NOTE

Guidance on the permissible cumulative loss of load kl is given in the informative Annex H (Table H.1).

(5) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (6) At each load step, the stability of the installation shall be ensured.

C.1.5 Test results (1) Based on the collected data, at least the following relationships shall be graphed:: ⎯ plot of “load-loss versus time” at the highest load of each cycle after lock-off; ⎯ plot of “kl versus anchor load” .

(2) Based on the collected data, at least the following characteristic shall be determined, where relevant: ⎯ anchor pull-out resistance R a. NOTE

Guidance on the determination of Ra is given in the informative Annex H.

C.2 Suitabili ty test pro cedure C.2.1 General (1) A suitability test according to method 2 is a test in which an axial load is applied incrementally in at least three cycles to a ground anchor up to a proof load P p to confirm that a particular anchor design will be adequate in particular ground conditions. At the highest load of each cycle, the anchor head displacement relative to the structure is held constant. The test involves measurement of load loss, after lock-off, during a specified period.

C.2.2 Test anchor (1) Suitability tests may be performed on working anchors. C.2.2.1

Execution

(1) The method used for the installation of the test anchor shall be fully documented. NOTE Records should be made of relevant aspects of the installation including: installation procedure, soil- and hydro-geological conditions and if applicable, results of the tests and checks carried out on the anchor material and any difficulties encountered during execution.


27

ISO/DIS 22477-5

(2) Test anchors and any extension pieces required for testing shall be designed to satisfy the condition on the load being lower than the yield load of the material (EN1992, EN1993 or standards for other materials, where relevant).

C.2.3 Time period b etween inst allation and loading (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE


C.2.4 Test executi on C.2.4.1

Test prepar ation

(1) Prior to commencement of the test, the preparation shall at least include : a) installation of measurement devices and checking its normal and safe functioning; b) establishing a perimeter of safety around the test anchor; c) installation of the stressing system and checking its normal and safe functioning (e.g. it shall be checked that the stressing device is in the axis of the test anchor). (2) The displacement reference system shall be located in such a way that it is not affected by any displacement of the reaction system and it shall be protected against climatic effects. C.2.4.2

Proof load

(1) The proof load P p shall be defined prior to the test. C.2.4.3

Datum Load

(1) A datum load P a shall be applied to minimise movement of the anchor test set-up on initial loading. Usually, this datum load is taken equal to the minimum load between 50 kN and 10% of P p. C.2.4.4

Loading proc edure

(1) The loading procedure shown in Figure C.2 and Table C.2 should be followed for conducting suitability tests. (2) If the proof load has been reduced by more than 5% during the 15 min, after allowing for any temperature changes and movements of the anchored structure, then the anchorage should be subjected to two further proof load cycles and the behaviour recorded. If the 5% criterion is exceeded in either cycle, then the proof load should be reduced to a value at which compliance with this clause may be achieved. (3) On completion of the third load cycle, the load should be increased to 73% P p (permanent anchorage) or 88%Pp (temporary anchors) and locked-off. The load should be reread immediately after lock-off to establish the initial residual load. This moment represents zero time for monitoring the load-displacement-time behaviour for 10 days. If the load has not attained a constant value after allowing for temperature, structural movements and relaxation of the tendon, the test should be extended by monitoring at 7 days interval for a period up to 30 days or until the load becomes constant. . NOTE


(4) The load shall not be applied or released quicker than 10 kN per second .

28


ISO/DIS 22477-5

(5) As an alternative to the procedure defined in clauses (1) and (2), the proof load can be maintained by jacking and the anchor head displacement monitored after 15 min. If the creep displacement is more than 5% ∆e, where ∆e is the displacement equivalent to the amount of tendon shortening caused by a prestress load of 1% of the initial residual load Load [% of P P ]

15 min

5000 mi n or 15000 min

100

90

80

70

60

50

40

30

20

10

0 00

100

0

Time [min]

Figure C.2 — Loading procedure – Suitability test method 2 (permanent anchorage) Table C.2 — Loading procedure – Suitability test method 2 Minimum period of observation in minutes Test method 2

Load levels %Pp

Temporary anchorages

Permanent anchorages

Cycle 1*

Cycle 2 and 3

Cycle 1*

Cycle 2 and 3

10 40 80 100 80 40 10

10 40 80 100 80 40 10

10 33 66 100 66 33 10

10 33 66 100 66 33 10

1 1 1 15 1 1 1

* For this load cycle, there is no pause other than necessary for the recording of displacement data. NOTE The load levels are defined as percentages of a proof load assumed to be 1,25 times the working load for temporary anchorages and 1,5 times the working load for permanent anchorages.

C.2.4.5

Measur ement and checks

(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked.


29

ISO/DIS 22477-5

(2) The following measurement procedure shall be followed for performing suitability tests: a)

if necessary, after application of the datum load P a , the initial displacement s o shall be recorded;

b)

during the stressing stage, the displacement should be recorded at the beginning and end of each period;

c)

at the highest load of each cycle, if necessary, and after lock-off, the value of the load loss kl at the anchor head shall at least be recorded at the following times (in minutes), depending on the duration of the load application: 0→5→15→50→150→500→1500 (1 day)

→5000

(3 days)

→15000

(10 days)


d)


(3) At the highest load of each cycle, the value of k l shall be checked. NOTE

Guidance on the permissible cumulative loss of load kl is given in the informative Annex H Table H1.

(4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured. (6) As an alternative to the above measurement procedure, displacement-time data may be monitored commencing at the final load (73%P p for a permanent anchorage) for a period of 10 days. If the displacement has not reached a constant value after allowing for temperature, structural movements and creep of tendon, the test should be extended by monitoring at 7 days interval, for a period up to 30 days or until the displacement becomes constant.

C.2.5 Test results (1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “load-loss versus time” at the highest load of each cycle after lock-off. ⎯ plot of “kl versus anchor load” .

(2) Based on the collected data, at least the following characteristics shall be determined: ⎯ kl value at the proof load and after lock-off. NOTE

If necessary, the pull out anchor resistances shall be determined (see also C.1.5).

C.3 Accept ance test procedure C.3.1 General (1) An acceptance test according to method 2 is a test in which an axial load is applied incrementally in 2 cycles to a ground anchor up to a proof load P p to confirm that a particular anchor meets the design requirements. At the highest load of each cycle, the anchor head displacement relative to the structure is held constant. The test involves measurement of load loss, after lock-off, during a specified period. NOTE

30

Acceptance tests are compulsory for all grouted anchors (EN 1997-1).


ISO/DIS 22477-5

C.3.2 Time between ins tallati on and testi ng (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE


C.3.3 Test execution C.3.3.1

Test preparat ion

(1) Prior to commencement of the test, the preparation shall at least include : a) installation of measurement devices and checking their normal and safe functioning; b) establishing a perimeter of safety around the test anchor; c) installation of the stressing system and checking its normal and safe functioning (e.g. it shall be checked that the stressing device is in the axis of the test anchor). (2) The displacement reference system shall be located in such a way that it is not affected by any displacement of the reaction system and it shall be protected against climatic effects. C.3.3.2

Proof load

(1) The proof load P p shall be defined prior to the test. C.3.3.3

Datum Load

(1) A datum load Pa shall be applied to minimise movement of the anchor test set-up on initial loading.

C.3.3.4

Loading proc edure

(1) The loading procedure shown in Figure C.3 and Table C.3 should be followed for conducting acceptance tests. (2) On completion of the second load cycle, the load should be increased to 73% P p (permanent anchorage) or 88%Pp (temporary anchors) and locked-off. The load should be reread immediately after lock-off to establish the initial residual load. This moment represents zero time for monitoring the load-displacement-time behaviour for 10 days. If the rate of load loss is higher than 1%, after allowing for temperature, structural movements and relaxation of the tendon, the test may be extended by taking readings at observations periods up to 10 days. NOTE


(3) The load shall not be applied or released quicker than 10 kN per second . (4) For pre-stressed anchors, where there is significant friction in the free tendon length, a partial cycle may be performed to determine the no-friction curve to be able to calculate the apparent tendon free length more accurately (see also C.3.3.5). (5) Restressing or constant load methods may be used to monitor the displacement at the initial residual load.


31

ISO/DIS 22477-5

Load [% of PP ]

15 min

5000 mi n or 15000 min

100

90

80

70

60

50

40

30

20

10

0 200

100

0

Time [min]

Figure C.3 — Loading pr ocedure – Accept ance test method 2 (permanent anchor ages) Table C.3 — Loading pr ocedure – Acceptanc e test method 2 Minimum period of observation in minutes Test method 2

Load levels %Pp

Temporary anchorage

Permanent anchorage

Cycle 1*

Cycle 2

Cycle 1*

Cycle 2

10 40 80 100 80 40 10

10 40 80 100 80 40 10

10 33 66 100 66 33 10

10 33 66 100 66 33 10

1 1 1 15 1 1 1

* For this load cycle, there is no pause other than necessary for the recording of displacement data. NOTE: The load levels are defined as percentages of a proof load assumed to be 1,25 times the working load for temporary anchorages and 1,5 times the working load for permanent anchorages.

C.3.3.5

Measurement and checks

(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing acceptance tests: a)

32



ISO/DIS 22477-5

b)

during the stressing stage, at the highest load of each cycle and after lock-off, the value of the load loss k l at the anchor head shall at least be recorded at the following times (in minutes) depending on the duration of the load application: 0→5→15→50→150→500→1500


c)


(3) At the highest load of each cycle, the value of k l shall be checked. NOTE

Guidance on the permissible cumulative loss of load kl is given in the informative Annex H (Table H.1).

(4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured.

C.3.4 Test results (1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “load-loss versus time” at the highest load of each cycle and after lock-off.; ⎯ plot of “kl versus anchor load” .

(2) Based on the collected data, at least the following characteristics shall be determined: ⎯ kl value at the proof load and after lock-off.

(3) The apparent tendon free length should be calculated (Informative Annex J).


33

ISO/DIS 22477-5

An nex D (informative) Examples of t est reports : Metho d 2

34


ISO/DIS 22477-5

D.1 Investigation test METHOD 2 – CYCLIC ANCHOR TEST

INVESTIGATION TEST

Organism :

Site :

TENDON CHARACTERISTICS

Location reference : xxxxx

Tendon free length

Ltf (m)

:

Tendon bond length

Ltb (m)

:

Extension length

Le (m)

:

Inclination

β (deg)

:

2

:

Section

At (cm )

Modulus

Et (MPa) :


P β

Le Ltf

BOND CHARACTERISTICS Anchor length

Lfixed (m) 2

Tool diameter

A (cm )

Ltb

: : TEST MEASUREMENT

CYCLE NUMBER

0

1

2

3

4

5

6

7

8

100

100

Lock-off load (kN) kl (kN) t = 5 minutes

-

kl (kN) t = 15 minutes

-

kl (kN) t = 5000 minutes

-

-

-

-

-

-

-

10

25

37,5

50

62,5

75

87,5

% of P P Date of the test :

Operators :

Observations : Load [%P P] 100

5000or 15000 or 50000 min

Cumulative loss of load kl (%) 20

90

15 min

80

18 16

15min

70

14 15min

12

60 15min

50

10

Pp

8

15min

40

6

30

15min

4

20

2

10

0 0 0

1

Time[min]

10

100

Time (min) 10000

1000

k6 (% Pp) for a 2 time periods l

Cumulative loss of load kl (%) s20 (mm)

5,5

17,5

5 4,5

15 Pp

4

12,5

3,5 3

10

2,5

7,5

2

Allowable

5

1,5 1

2,5

0,5 c

P

u

0

0 0

1

2

3

4

5

6

7

Period 8 Number 9

10

0

P

a

20

40

60

80

Load (% P ) 100 P

TEST RESULTS Cumulative loss of load at Pp for 7 time periods - kl (% Pp) :

Figure D.1 — Cyclic tension test (Method 2) – Example of investigation test report


35

ISO/DIS 22477-5

D.2 Suitability test METHOD 2 – CYCLIC ANCHOR TEST

SUITABIL ITY TEST




P β

Le Ltf

BOND CHARACTERISTICS Anchor length Lfixed (m) : 2 Tool diameter A (cm ) :

Ltb

CYCLE NUMBER 0 Lock off load (kN) kl (kN) t = 5 minutes kl (kN) t = 15 minutes kl (kN) t = 5000 minutes % P P 10 Date of the test : Observations : Permanent anchorage Load [% of PP ]

15 min

1

2

100

TEST MEASUREMENT 3 Final

100 100 Operators :

73

5000 min or 15000 min

100


90

9

80

8

70

7

60

6 5

50

Pp

4

40

3 30

2 20

1 10

0 1

0 200

100

0

10

100

Time (min) 10000

1000

ime [min]

Cumulative loss of load k l (%) s (mm) 10

Cumulative loss of load kl (%) for a 2 time periods 2,5

9

2,25

8

Allowable

2

7

kl (Pp) for a 2 time periods

1,75

6

1,5

Pp

5

1,25

4

1

3

0,75

2

0,5

1

0,25 0

0 0

1

2

3

4

5

6

7

Period 8 Number 9

10

0

Pa

20

40

60

80

Load (% P100 ) P

TEST RESULTS Cumulative loss of load at P p for 2 time periods - k l (% Pp) : Figure D.2 — Cyclic tension test (Method 2) – Example of suitability test report

36


ISO/DIS 22477-5

D.3 Acceptance test METHOD 2 – CYCLIC ANCHOR TEST

ACCEPTANCE TEST



P β

Le Ltf


Ltb

CYCLE NUMBER 0 Lock off load (kN) kl (kN) t = 5 minutes kl (kN) t = 15 minutes kl (kN) t = 50 minutes % P P 10 Date of the test : Observations : Permanent anchorage Load [% of P P ]

15 min


TEST MEASUREMENT 2 100 Operators :

1

100

-

-

5000 min or 15000 min

100


90

80

4

70

3

60

50

2

40

Pp

30

1 20

10

0 1

0 200

100

0

10

Time (min)100

Time [min]

Cumulative loss of load k l (%) at Pp s4(mm) 3,5 Allowable 3 2,5 2

kl (Pp) for a 3 time periods

1,5 1 0,5 0 0

1

2

Period Number 3

4

TEST RESULTS Cumulative loss of load at P p for 3 time periods - k l (% Pp) :

Figure D.3 — Cyclic t ension t est (Metho d 2) – Example of acceptanc e test report


37

ISO/DIS 22477-5

An nex E (normative) Test p roc edure: Metho d 3

E.1 Investigati on test pro cedure E.1.1 General (1) An Investigation test according to method 3 is a test in which an axial load is applied by step to a ground anchor up to a proof load P p, which is designed to reach failure of the interaction soil-anchor. Each load is maintained constant during a specified period of time. The test involves measurement of tendon head displacement versus applied load and, for each load step, measurement of tendon head displacement versus time.

E.1.2 Test anchors (1) Investigation tests shall be carried out on anchors which are not part of an actual structure, installed prior to the installation of working anchors. E.1.2.1

Test loc ation

(1) Soil-conditions at the test location shall be representative for the soil conditions of working anchors. (2) The results of the site investigation shall be considered when selecting a test anchor location. E.1.2.2

Execution

(1) Test anchors shall be representative of working anchors. (2) Test anchors shall be installed using the same installation procedures as working anchors. (3) The method used for the installation of test anchors shall be fully documented. NOTE 1 Records should be made of relevant aspects of the installation including: installation procedure, soil and hydro-geological conditions and if applicable, results of the tests and checks carried out on the anchor material and any difficulties encountered during execution.

(4) Test anchors should have the same inclination as working anchors. (5) The anchor bond length of a test anchor should be representative of the anchor bond length of a working anchor. (6) Test anchors with a shorter bond length as working anchors may be considered, provided that this length is not less than 5 m NOTE 2 Normally, for investigation tests the bond length must be the same as for the working anchors. The extrapolation of investigation results to the working anchors should be limited to 2 meters.

(7) Test anchors and any extension pieces required for testing shall be designed to satisfy the conditions on the load being lower than the yield load of the material (EN1992, EN1993 or standards for other materials, where relevant).

38


ISO/DIS 22477-5

E.1.3 Time period between installation and testing (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE


E.1.4 Test executi on E.1.4.1

Test preparat ion


installation of measurement devices and checking its normal and safe functioning;

b)


c)


(2) The displacement reference system shall be located in such a way that it is not affected by any displacement of the reaction system and it shall be protected against climatic effects. E.1.4.2

Maxim um test load

(1) The maximum test load P p shall be defined prior to t he test. E.1.4.3

Datum Load

(1) A datum load P a shall be applied to minimise movement of the anchor test set-up on initial loading. Usually, this datum load is taken equal to the minimum load between 50 kN and 10% of P p. E.1.4.4

Loading proc edure

(1) The loading procedure shown in Figure E.1 and Table E.1 should be followed for conducting Investigation tests. (2) The load shall not be applied or released quicker than 10 kN per second . (3) A loading stage lasts normally for 60 min. It may be stopped after 30 minutes if the value of α3 is less than 1 mm. NOTE

Guidance on the determination of α is given in the informative Annex G.1.

(4) A loading stage shall be stopped when the value of α reaches 5 mm. (5) The final unloading will be done step by step with 0,2P p decrements. At each step, the load will be maintained constant for the time necessary to make all readings. (6) It is useful to know the total friction on the anchor to determine the effective load at the top of the bond length. This can be achieved by adding one cycle, starting at 70% P p down to 10% of P p and back to 70% Pp with unloading and reloading steps of 10% of P p.


39

ISO/DIS 22477-5

100

60 min

Load (% PP) 60 min

90 60 min 80

2 min 60 min

70 60 min 60 60 min

2 min

50 60 min 40 60 min

30

2 min

20 5 min 10

Time (min) 0 0

50

100

150

200

250

300

350

400

450

500

Figure E.1 — Loading procedure – Investigation test method 3 Table E.1 — Loading procedure – Investigation test method 3 Datum load 10 0

Load increments % PP Step 3 Step 4 Step 5

Step 1

Step 2

25 60

40 60

50 60

60 60

(30)

(30)

(30)

(30)

Step 6

Step 7

Step 8

Step number

70 60

80 60

90 60

100 60

(30)

(30)

(30)

(30)

% PP Period of observation (minutes)

Example given for 8 steps

E.1.4.5

Measur ement and checks

(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing Investigation tests: a)


b)

at each step, the time origin is taken immediately when the expected load is reached;

c)

during the stressing stage, at each load step, if necessary, the load and the anchor head-displacement shall at least be recorded at the successive monitoring times (in minutes) as indicated below: 0→1→2→3→4→5→7→10→15→20→30→45→60

NOTE Where relevant, the control of the load and of the anchor head-displacement should be performed with a periodicity less than the successive monitoring times indicated above.

40


ISO/DIS 22477-5

d)

during the de-stressing stage, the load and the anchor head-displacement shall be recorded at least at the end of each step and five minutes after the total de-stressing.

e)


(3) At each load step, the value of α shall be checked. (4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load, the stability of the installation shall be ensured.

E.1.5 Test results (1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “anchor head displacement versus anchor load or applied jack pressure” at the beginning and at the end of each load step; ⎯ plot of “anchor head displacement versus time” for each load step; ⎯ plot of “α3 versus anchor load or bond anchor load” if possible”. NOTE

The bond anchor load can be calculated taking account of the total friction determined by the cycle at 70% of Pp.

(2) Based on the collected data, at least the following characteristics shall be determined: ⎯ critical creep load Pc ⎯ anchor pull-out resistance R a. NOTE

Guidance on the determination of Pc and Ra is given in the informative Annex I.

E.2 Suitabili ty test pro cedure E.2.1 General (1) A suitability test according to method 3 is a test in which an axial load is applied by step to a ground anchor up to a proof load P p to confirm that a particular anchor design will be adequate in particular ground conditions. Each load is maintained constant during a specified period. The test involves measurement of tendon head displacement versus applied load and, for each load step, measurement of tendon head displacement versus time. NOTE Suitability tests are compulsory for grouted anchors, screw anchors and rock bolts (EN 1997-1). Pp is usually determined to reach at least a load greater than the anchor load at the serviceability design state.

E.2.2 Test ancho r (1) Suitability tests may be performed on working anchors. E.2.2.1

Execution

(1) The method used for the installation of the test anchor shall be fully documented.


41

ISO/DIS 22477-5

NOTE Records should be made of relevant aspects of the installation including : installation procedure, soil- and hydro-geological conditions and if applicable, results of the tests and checks carried out on the anchor material and any difficulties encountered during execution.

(2) Test anchors and any extension pieces required for testing shall be designed to satisfy the conditions on the load being lower than the yield load of the material (EN1992, EN1993 or standards for other materials, where relevant).

E.2.3 Time period between installation and testing (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE



Test preparat ion



b)


c)



Proof load

(1) The proof load P p shall be defined prior to the test. NOTE If this anchor is a working anchor, the proof load Pp must be at the maximum equal to the minimum critical creep load Pc obtained on the different investigation test of same type.

E.2.4.3

Datum Load

(1) A datum load P a shall be applied to minimise movement of the anchor test set-up on initial loading. Usually, this datum load is taken equal to the minimum load between 50 kN and 10% of P p. E.2.4.4

Loading proc edure

(1) The loading procedure shown in Figure E.2 and Table E.2 should be followed for conducting suitability tests. (2) The load shall not be applied or released quicker than 10 kN per second . (3) A loading stage may be stopped at 30 minutes if the value of α3 is less than 1 mm.. NOTE

Guidance on the determination of α3 is given in the informative Annex G.1.

(4) A loading stage shall be stopped when the value of α3 reaches 2 mm.

42


ISO/DIS 22477-5

(5) During the final de-stressing, the load shall be maintained constant at least at 0,75 P p, 0,50 Pp, 0,25 Pp and 0.1 Pp during the time necessary to make all readings at each step. (6) It is useful to know the total friction on the anchor to determine the effective load at the top of the bond length. This can be achieved by adding one cycle at 70% of P p down to 10% of Pp and back to 70% of Fp with unloading and reloading steps of 15% of P p. or less.

Figure E.2 — Loading pro cedure – Suitabil ity test method 3 Table E.2 — Loading procedure – Suitability test method 3

Datum load 10 0

1)

E.2.4.5

Step 1

Load incr ements % P p Step 2 Step 3 Step 4

1)

Step 5

Step 6

Step number % P p

25 60

40 60

55 60

70 60

85 60

100 60

(30)

(30)

(30)

(30)

(30)

(30)

Period of observation (minutes)

Example given for 6 s teps


(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing Suitability tests: a)



43

ISO/DIS 22477-5

b) at each step, the time origin is taken immediately when the expected load is reached; c)

during the stressing stage, at each load step, if necessary, the load and the anchor head-displacement shall at least be recorded at the successive monitoring times (in minutes) as indicated below: 0→1→2→3→4→5→7→10→15→20→30→45→60

NOTE Where relevant, the control of the load and of the anchor head-displacement should be performed with a periodicity less than the successive monitoring times indicated above.

d)

during the de-stressing stage, the load and the anchor head-displacement shall be recorded at least at the end of each step and five minutes after the total de-stressing.

e)


(3) At each load step, the value of α shall be checked. (4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured.

E.2.5 Test resul ts (1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “anchor head displacement versus anchor load or applied jack pressure” at the beginning and at the end of each load step; ⎯ plot of “anchor head displacement versus time” for each load step; ⎯ plot of “α versus anchor load or bond anchor load, when possible”. NOTE 1 The bond anchor load can be calculated taking account of the total friction determined by the cycle at 70% of Pp.

(2) Based on the collected data, at least the following characteristics shall be determined: ⎯ α3 value at the proof load. NOTE 2 If reached during this test, the critical creep load and pull out anchor resistances shall be determined (Guidance on the determination of Pc and Ra is given in informative Annex I).

E.3 Accept ance test pro cedure E.3.1 General (1) An acceptance test according to method 3 is a test in which an axial load is applied by step to a ground anchor up to a proof load P p to confirm that a particular anchor meets the design requirements. Each load is maintained constant only during the necessary time to perform the measurement (extraction of the tendon head, load). At the proof load the measurement of the extraction of the tendon head versus time during a specified time is recorded. NOTE

44

Acceptance tests are compulsory for all grouted anchors.


ISO/DIS 22477-5

E.3.2 Time period between installation and testing (1) Between the installation of test anchors and the beginning of the test, adequate time shall be allowed to ensure that the required strength of the anchor material is achieved. NOTE Depending on the materials used, this usually takes one week.


Test preparat ion

(1) Prior to commencement of the test, the preparation shall at least include : a)


b)


c)



Proof load

(1) The proof load P p shall be defined prior to the test. NOTE The proof load Pp must be at the maximum equal to the minimum critical creep load Pc obtained from the different investigation tests of same type.

E.3.3.3

Datum Load

(1) A datum load Pa shall be applied to minimise movement of the anchor test set-up on initial loading.

Usually, this datum load is taken equal to the minimum load between 50 kN and 10% of P p. E.3.3.4

Loading proc edure

(1) The loading procedure shown in Figure E.3 and Tables E.3 and E4 should be followed for conducting acceptance tests. (2) The load shall not be applied or released quicker than 10 kN per second . (3) At proof load, the value of α3 shall be checked. (4) For pre-stressed anchors, a complete or partial cycle may be performed to determine the no-friction curve to be able to calculate the apparent tendon free length more accurately (see also E.3.3.5) and also the existing load at lock off at the top of the bond length.


45

ISO/DIS 22477-5

) p P % (

1

d a o L

2

Time (min) Key 1 Loading with partial or complete cycle 2 Loading without cycle.

Figure E.3 — Loading procedure – Acceptance test method 3 Table E.3 — Loading procedure without cycle – Acceptance test method 3 1)

Datum load 10 1)

Step 1 30

Load increments % P p Step 2 Step 3 Step 4 50

70

Step 5

90

100

Time necessary to perform measurement

15

Step number % Pp Period of observation (minutes)

Example given for 5 steps

Table E.4 — Loading procedure with cycle – Acceptance test method 3 Load step

Datum load

Load (%Pp) Observation period (min)

10

Step 1

Step 2

Step 3

Step 4

Step 5

Step C6

Step C7

Step C8

Step C9

Step C10

30 50 70 90 100 90 80 70 80 90 Time necessary to perform Time necessary to perform 15 measurements measurements Same example as in Table E.3

Step C11

Lock off

100

(5) Lock–off procedure

46


ISO/DIS 22477-5

At the end of the stressing procedure or after the cycle, the lock-off operation must be done. Different procedures are be applied, depending on whether a cycle was performed or not: a) Lock-off after acceptance test without cycle: From Pp, unloading with an adapted procedure for lock off with at least 5 points to built correctly the final destressing destressing and lock off curve. b) Lock-off after acceptance test with cycle: At the end of the cycle, if de-stressing is needed to install the wedges, this de-stressing should be done. then you put the wedges, and you reload up to the pressure for lock off with at a minimum of 6 points and then do the lock off with at least 5 points. (an example is given an annexe), At the end of the cycle, if you don’t need a de-stressing to put the wedges, you apply the same program than for the lock off without cycle (a). E.3.3.5


(1) Prior to commencement of the test, it shall be ensured that external sources do not bring important disturbances to measurement and normal functioning of the measurement equipment shall be checked. (2) The following measurement procedure shall be followed for performing Acceptance tests: a)

after application of the datum load P a , the initial displacement s o shall be recorded;

b)

at each loadstep, the time origin is taken immediately when the expected load is reached.

c)

during the stressing stage, at each load step, the load (or jack pressure) and the anchor headdisplacement shall be recorded. At proof load, the successive monitoring times (in minutes) as indicated below: 0 1→2→3→4→5→7→10→15

NOTE Where relevant (α3 larger than a given limit value), the load and of the anchor head-displacement should be measured during a longer period than indicated above, for example during 1h with measurement at 25, 30, 45, and 60 min, in order to check again the α3 value at the end of the observation time.

d)

during the de-stressing stage, the load (or the pressure) and the anchor head-displacement shall be recorded at each step down to the datum load before the total de-stressing.

e)


(3) At proof load, the value of α shall be checked. (4) At each load step, the stressing and reaction devices shall be visually inspected in order to detect any degradation. (5) At each load step, the stability of the installation shall be ensured.

E.3.4 Test results (1) Based on the collected data, at least the following relationships shall be graphed: ⎯ plot of “anchor head displacement versus pressure or anchor load”; ⎯ plot of “anchor head displacement versus time” at the proof load.

(2) Based on the collected data, at least the following characteristics shall be determined:


47

ISO/DIS 22477-5

⎯ anchor head displacement at the proof load; ⎯ α3 value at proof load.

(3) The apparent tendon free length should be calculated. NOTE The apparent tendon free length Lapp is the theoretical free length of the tendon up to the connection of the tendon to the stressing jack deduced from the test. The determination of Lapp is presented in Annex J.

48


ISO/DIS 22477-5

Ann ex F (informative) Examples of t est reports : Method 3


49

ISO/DIS 22477-5

F.1 Investigati on test METHOD 3 – MAINTAINED ANCHOR TEST

INVESTIGATION TEST



Reference : D xxxxx Date of installation : xx/xx/xxxx

P β

Le Ltf


Ltb Loading stage

STEP NUMBER

0

1

2

3

4

De-stressing (t = 2 min)

5

6

7

8

9

10

11

12

-

-

-

-

LOAD (kN)

s (mm) t = 30 minutes s (mm) t = 45 minutes s (mm) t = 60 minutes

-

α (mm)

-

10

% PP

25

40

50

Date of the test :

60

70

80

90

100

-

-

-

-

75

50

25

10

Operators :

Observations : 100

Load [% PP]

60 min

s (mm) 150 60 min

90 60 min 80

2 min

125

60 min 70

100

60 min 60 60 min

2 min

75

50 60 min 40

50 60 min

30

2 min

20

25

5 min 10

Time [min]

0

0 0

50

100

150

200

250

300

350

400

450

1

500

s (mm) 150

Time (min)

10

100

6 (mm)

α

5,5

125

5 4,5 4

100

3,5

75

3 2,5

50

2 1,5

25

1 0,5

0

Pu

0

0

Pa

20

40

60

80Load (% PP) 100

TEST RESULTS Anchor critical resistance : Rc (kN) = O,9 P c

0

Pa

20

40

Anchor pull out resistance :

60 Pc

80

Load (% P100 ) P

Ra (kN) = Pu =

Figure F.1 — Maintained tension test (Method 3) – Example of investigation test report

50


ISO/DIS 22477-5

F.2 Suitabil ity test METHOD 3 – MAINTAINED ANCHOR TEST


SUITABIL ITY TEST



P β

Le Ltf


Ltb Loading stage

STEP NUMBER

0

1

2

3

De-stressing (t = 2 min)

4

5

6

7

8

9

10

-

-

-

-

LOAD (kN)

s (mm) t = 30 minutes s (mm) t = 45 minutes s (mm) t = 60 minutes

-

α (mm)

-

-

% P P

-

10

Date of the test :

25

40

55

70

85

100

-

-

-

-

75

50

25

10

Operators :

Observations : 100

Load [% PP]

60 min

s (mm) 150

90

60 min 2 min

80

125

60 min 70

100 60

60 min 2 min

50

75

60 min 40

50

60 min

30

2 min

20

25

5 min

10

Time [min]

0

0 0

50

100

150

200

250

300

350

400

450

500

1

Time (min)

10

100

4 (mm)

α

s (mm) 150

3,5

125 3 α PP

s PP

100

2,5 2

75

1,5

50 1

25

0,5 PP 0

0 0

Pa

20

40

60

TEST RESULTS Anchor head displacement at Pp :

80

Load (% 100 PP )

spp (mm) =

0

Pa

α value at Pp :

20

40

60

80

Load (% P100 ) P

αpp (mm) =

Figure F.2 — Maintained tension test (Method 3) – Example of suitability test report


51

ISO/DIS 22477-5

F.3 Acc eptance test METHOD 3 – MAINTAINED ANCHOR TEST

ACCEPTANCE TEST

Organism :

Site :

TENDON CHARACTERISTICS

Location reference : xxxxx

Tendon free length

Ltf (m)

:

Tendon bond length

Ltb (m)

:

Extension length

Le (m)

:

Inclination

β (deg)

:

2

:

Section

At (cm )

Modulus

Et (MPa) :


P β

Le Ltf

BOND CHARACTERISTICS Anchor length

Lfixed (m) 2

Tool diameter

A (cm )

Ltb

: : Loading stage

STEP NUMBER

0

1

2

3

4

De-stressing 5

6

7

8

9

-

-

-

-

LOAD (kN) s (mm) t = 2 minutes

-

s (mm) t = 5 minutes

-

s (mm) t = 15 minutes

-

α (mm)

% P p

-

10

Date of the test :

30

50

70

90

100

-

-

-

-

90

80

70

10

Operators :

Observations : 100 [% PP] Load

15 min

s (mm) 150 90 80

125

70

100

60 50

75

40

50

30 20

25

10

Time [min]

0

0 0

10

20

30

40

50

60

70

80

90

100

1

10

Time (min)

100

Dt = 15 min 100 Load [% PP] ∆ Pf

80

60

∆P

40

20 ∆s

0 0

50

100

s [mm]150

TEST RESULTS Anchor head displacement at Pp : sp (mm) =

α value at Pp : αp (mm) =

Figure F.3 — Maintained tens ion t est (Method 3) – Example of acc eptance test report

52


ISO/DIS 22477-5

Annex G (informative) Guidance on allow able (Method 1) and test interpretation

1

G.1 Determination of

Figure G.1 — Time displacement plot for calculation the creep ratio

1

Determination of α1 The creep is defined as the creep ratio end of the curve time vs. displacement: α 1

α 1 at

constant anchor load (Figure G.1), derived from the linear

= (sb – sa) / lg (t b /t a)

with sa

displacement of the anchor head at the time t c

sb

displacement of the anchor head at the time t b

t a

start of the respective time interval

t b

end of the respective time interval


53

ISO/DIS 22477-5

G.2 Suitability test Evidence is required that displacements or creep ratios are not in excess of those indicated in table G.1.

Table G.1 — Suitability tests: observation tim es on allow able displacements or creep ratios at proof load Pp Temporary anchor

1

Permanent anchor

non cohesive soil and rock

cohesive soil

non cohesive soil and rock

cohesive soil

Pp

Pp

Pp

Pp

t a [min]

10

20

20

60

t b [min]

30

60

60

180

≤ 0,5

≤ 0,5

≤ 0,5

≤ 0,5

≥ 30

≥ 60

≥ 120

≥ 720

2,0

2,0

2,0

2,0

Proof load Test with minimum observation time meeting the requirement:

2

Displacements: ∆s =

3

sb – sa [mm]

Test with extended observation time: t b [min] creep ratio

α 1 [mm]

* α 1 derived from the linear end of the curve time vs. displacement, Fig. G.1

If the criterion α 1 = 2,0 mm is exceeded before reaching the proof load P p during the suitability test of anchor, the permissible anchor load for all anchors covered by the test shall be determined on the basis of the lowest value of the test. Otherwise, additional suitability tests shall be carried out (e.g. on anchors with improved construction procedure).

G.3 Acceptance test Evidence is required that displacements and creep ratios are not in excess of the values indicated in Table G.2.

54


ISO/DIS 22477-5

Table G.2 — Observation times and permissible displacements and creep ratios at the proof load Pp of acceptance tests Non-cohesive soil and rock

Cohesive soil

Pp

Pp

t a [min]

2

5

t b [min]

5

15

≤ 0,2

≤ 0,25

>5

> 15

≤ 2,0

≤ 2,0

Proof load acc. to EN 1997-1 Observation time:

Displacement ∆s =

sb – sa [mm]

Extended observation time: t b [min] creep ratio

α 1 [mm]

*

* α 1 derived from the linear end of the curve time vs. displacement


55

ISO/DIS 22477-5

Ann ex H (informative) Guidance on allowable k i and on test int erpretation: Method 2

H.1 Permissib le cumulative loss of lo ad kl (1) The cumulative loss of load k l over the different times of observation should not exceed the values given in table H.1. Table H.1 — Permissible cumulative loss of load k l Time of observation in minutes 5 15 50 150 500 1500 (approx 1 day) 5000 (approx 3 days) 15000 (approx 10 days)

Time period number 1 2 3 4 5 6 7 8

Permissi ble cumulative loss of lo ad k l (% Appl ied Load) 1 2 3 4 5 6 7 8

H.1.1 Investigation test (1) If the cumulative loss of load, at the lock-off load level, after 7 time periods (3 days) does not exceed the allowable and the load-loss per time interval is not increasing then the test may terminate and the load cycling of the anchor be continued to P p or to failure. Should the allowable loss of load be exceeded and/or the load loss per time interval be increasing the observation period may be extended to the eighth period or longer until stability is achieved. If stability is not achieved the applied load is too high for a serviceability condition but the test should be continued to determine the failure load.

H.1.2 Suitability test (1) The cumulative loss of load k l, at the proposed lock-off load, after 7 time periods (3 days) should not exceed the allowable values given in table H.1.

H.1.3 Acceptance test (1) The maximum cumulative loss of load k l, at the lock-off load level P o should not exceed: ⎯ 3%Po in 50 min (3 time periods); or ⎯ 6%Po in 24 hr (6 time periods).

H.2 Determin ation of the anchor cri tic al resist ance Rc (1) The anchor critical resistance R c may be calculated as follows:

56


ISO/DIS 22477-5

Rc = 0,9. Pc Where: Pc is the critical creep load determined as indicated in Figure H.1; NOTE The anchor critical resistance Rc is the load corresponding to the end of the first pseudo linear part of the plot giving the cumulative loss of load for a 2 time periods versus anchor load. As it is often difficult to determine Rc accurately, an easier method consists of determining the anchor load Pc which separates the field with low values of kl (typically less than 1 %) from the field with high values of kl, and to determine Rc from Pc.as indicated above.

k6l (% Pp) for a 2 time periods 5,5 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 0

Pa

20

40

60

P 80 c

Load (% P ) 100 P

Figure H.1 — Determination of the anchor critical resistance – Investigation test

H.3 Determin ation of the anchor pull out resis tance Ra (1) The anchor pull out resistance R a may be calculated as follows: Ra = Pu where: Pu is the ultimate load determined as indicated in Figure H.2 . NOTE The anchor pull out resistance Pu is the load corresponding to the vertical asymptote of the plot giving the cumulative loss of load kl for a 2 time periods versus anchor load (see Figure H.2a). If the asymptote cannot be easily determined, it may be considered that Pu (see Figure H.2b) is the load corresponding to a kl value equal to 5 % for a 2 time periods of observation.


57

ISO/DIS 22477-5

k6l (% Pp) for a 2 time periods 5,5 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5

Pu

0 0

Pa 20

40

60

80

100

120

Load (% PP ) 140

Figure H.2.a k6l (% Pp) for a 2 time periods 5,5 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5

Pu

0 0

Pa

20

40

60

80

Load (% P 100 P)

Figure H.2.b

Figure H.2 — Determination of the anchor pull out resistance – Investigation test NOTE For pre-stressed anchors, it may be considered that Pu is the load corresponding to an anchor head displacement calculated as ∆l = ∆le + 0,01 m.

with

∆l e =

R t ;d .(Lt + Le ) At .E t

∆le :

= theoretical extension of the length of the tendon under Rt;d.

Rt;d

= design value of structural resistance of the tendon or the extension piece calculated

Lt, Le = length of the tendon, length of extension piece At

= area of the tendon or extension piece, whichever is the smaller

Et

= Young’s modulus of the tendon or the extension piece, whichever is the smaller

58


ISO/DIS 22477-5

Ann ex I (informative) Guidance on allowable

3

and test interpretation: Metho d 3

I.1 Determination of (1) The displacement under constant load should be determined over the last two time intervals of the observation periods (see Figure G.1) as follows: α = (s2-s1) / lg (t 2/t1)

where: s1 is the head displacement at time t 1 ; s2 is the head displacement at time t 2 ; t1

is the time after application of load increment.

T2 is the time at the end of the observed period under constant load.

s

α = (s2 – s1) / lg (t2/t1)

αi + 1

αi

lg t 1

5

10

20

45

100

t (min)

Figure I.1 — Determination of the slope of the stabilization curve at c onstant load

I.1.1 All owabl e value of

3 for

suitability tests

(1) At each load step, the displacement due to creep should be measured over the last two time intervals of the observation period (see E.2.4.5).


59

ISO/DIS 22477-5

(2) Where no Investigation tests have been performed, the maximum creep displacement ( α3) should not exceed : ⎯ 0,8 mm at proof load level;

(3) Where Investigation tests have been performed, the maximum creep displacement ( α3) at the proof load level should not exceed: ⎯ 1,2 mm for a temporary anchor; ⎯ 1,0 mm for a permanent anchor.

I.1.2 All owabl e value of

3 for

acceptance tests

(1) At each load step, the displacement due to creep should be measured over the two last time intervals of the observation period (see E.3.3.5). (2) Where no Investigation tests have been performed, the maximum creep displacement ( α3) at the proof load level should not exceed: ⎯ 1,2 mm for permanent or temporary anchors;

(3) Where Investigation tests have been performed, the maximum creep displacement ( α3) at the proof load level should not exceed: ⎯ 1,8 mm for a temporary anchor; ⎯ 1,5 mm for a permanent anchor.

I.2 Determinatio n of the crit ical creep load Pc The anchor critical creep load P c is the load corresponding to the end of the first pseudo linear part of the “ α3 versus anchor load” plot. As it is sometimes difficult to determine P c accurately, an alternative method consists in determining the value of the anchor load P’ c which is the intersection of the first pseudo linear segment and a second line built with the last points of the “ α3 versus anchor load” curve. In this case, the critical creep load P c may be calculated as follows: Pc = 0,9 P’c where: P’c is the critical creep load determined as indicated in Figure I.2;

60


ISO/DIS 22477-5

α3 (mm) 3

2,5

2

1,5

1

0,5

0 0

P a

20

40

Pc

60

P’c

80

Load (% P ) 100 P

Figure I.2 — Determination of the anchor critical resistance – Investigation test

I.3 Determination of anchor pull o ut resistance Ra (1) The anchor pull out resistance R a may be calculated as follows: Ra = Pu Where: Pu is the ultimate load determined as indicated in Figure I.3. NOTE The anchor pull out resistance Pu is the load corresponding to the vertical asymptote of the “α3 versus anchor load” plot. If the asymptote cannot be easily determined, it may be considered that Pu for method 3 is the load corresponding to a α3 value equal to 5 mm (see Figure I.3).


61

ISO/DIS 22477-5

α3 (mm)

6 5,5 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 0

P a

20

40

60

80

Pu

100

Load (%Pp)

Figure I.3 — Determination of the anchor pull out resistance – Investigation test – Method 3

62


ISO/DIS 22477-5

Ann ex J (informative) Evaluation of th e apparent tendo n free lengt h

J.1 General The apparent tendon free length L app is the theoretical free length of the tendon up to the connection of the tendon to the stressing jack deduced from the test. It is calculated from the measurement of the tendon extension ∆s from the point of fixing the tendon to the jack or from a reference point coupled to the tendon. This measurement defines the location of a fictitious fixed anchor, which is compared to the end of the tendon free length and the start of the tendon bond length. Usually Lapp is calculated with the following formula:

L app =

A t .E t .∆s Pp − Pa − ∆Pf

where Lapp

is the apparent tendon free length;

At

is the cross-section of tendon;

E t

is the elastic modulus of the anchor tendon;

∆s

is the elastic extension of the tendon;

P p

is the proof load;

P a

is the datum load;

∆P f

is the friction resistance, to be estimated as indicated in Figure J.1.

NOTE When the friction resistance is negligible or has not been determined, a value of∆P f = 0 shall be taken for the calculation of Lapp. This will give an overestimated value of Lapp.

J.2 Determination of fricti on resistance Where there is significant friction in the free length, the method shown in Figure J.1 may be used. The hysteresis loop between a loading and an unloading curve is used to estimate the friction resistance ∆Pf on the magnitude of apparent elastic stiffness of the free length ( ∆P/∆s). If the friction resistance exceeds 0,05 P p it should be taken into account when determining the minimum proof load or lock-off load. If necessary the proof load may be reduced.


63

EN ISO 22477-5 Testing of anchorages DPC.pdf

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