Concerns on Grouting in Soils

GeoEng Co C onsultants SPEC IA IAL LIS IST TC IV IVIL IL AND GE GEOTEC HNIC NICA AL C ONS NSU ULTING ENG NGINEE INEER RS

C onc erns on Gr Groutin ing g in Soils

Dr Indrayogan Yogarajah GeoEng Co C ons nsult ulta ant nts s (S) Pt Pte Ltd

Scope of Presentation

•

Methods/Forms of grouting

•

Grouting fo for De Deep Ex Excavation

•

Effects of Grouting

•

Overcoming effects

•

Weed ou out so some mi misconceptions

Various forms of grouting – Jet grouting – Deep Soil Mixing – Deep Cement Mixing – Jet Mechanical Mixing – Wet Soil Mixing – Chemical grouting – Compaction grouting – Fissure grouting – In fill grouting GeoEng Co C onsultant nts s (S) Pte Ltd

Grouting – Grouting of soils is a process process of injecting a cementi cementitio tious us com compou pound/ nd/mix mixtur ture e into the gro ground und to to minim minimise ise one or more more of the following • Ingress Ingress of wate waterr (eg. (eg. Chemica Chemicall grouti grouting) ng) • Sti Stiffen ffening ing/str /streng engthe thenin ning g of soils (eg. (eg. Jet grouting, deep soil mixing, deep cement mixing etc.) • Lift Lifting ing of struct structure ures s (compac (compaction tion grou groutin ting) g) • Sea Sealin ling g of gaps gaps in rocks rocks (pe (perme rmeatio ation n grouting, fissure grouting)

Grouting • Soil fracturing • Soil str stre engt ngthe henin ning g • Soil compaction • Soil permeation

GeoEng Co C onsultant nts s (S) Pte Ltd

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Seal Se alin ing g of of CBP CBP,, Ret Retai aini ning ng Wa Wall ll Se Serv rvic ice e Gap Gap

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Soi oill im impr prov ovem emen entt fo for tun tunne nell lliing

•

Underpinning

Uses of Grouting • Improved soil base for excavations, especially in soft soils (most common use). - Improve overall stability - Reduce ground movements and subsidence - Reduce forces on retaining wall and strut loads

Improved soil

Grouting for Deep Excavation • High pressure grouting – Jet Grouting (JGP)

• Mixing only – – – –

Deep Soil Mixing (DSM) High PressureGrouting Deep Cement Mixing (DCM) Wet Soil Mixing (WSM) (WSM) Grout Mixed Piles (GMP) (GMP)

• Mixing and pressures

Mixing Methods

– Enhanced Grout Mixed Piles (EGMP) – Turbo Jet (TJ) – Jet Mechanical Mixing (JMM)

Grouting

RANGE RA NGE OF OF SOIL PARA PA RAMET METERS ERS FOR FOR VARIOUS GROUTING METHODS

Organic Clay Silt JGP DSM DCM WSM Enh_d GMP Turbo


Sand Gravel

Concerns of grouting • Desi sign gn Stage tage – – – Strength and Stiffness – Performance of grouting grouti ng methods – Behaviour of Earth Retaining Structures Structu res during Excavation

• Cons onstru truct ction ion Sta Stage ge – – – Quality of grouting – Heave/settlement and a nd lateral movements of the ground and/or Earth Retaining Structures – Performance of Earth Retaining Retain ing Structures during Excavation GeoEng Co C onsultant nts s (S) Pte Ltd

Jet Grouting


Overview • Jet Jet gro grout utin ing g use used d in in Sin Singa gapo pore re fo forr mor more e tha than n 20 20 years yea rs – exte extensi nsive ve expe experie rience nce.. We sho should uld not under-estimate local experience. experience . • Jet Jet grou groutt consi consist st of of high high pre press ssur ure e water water/gr /grou outt jets jets that “cuts” the soil by disinte disintegratin grating g the the soil soil matrix. The cut soil is mixed and partially replaced by the cement grout. As drill string is rotated and withdrawn, a column of cement mixed soil is formed. formed. GeoEng Co C onsultant nts s (S) Pte Ltd

Overview • Mech Mechan anic ical al pr prop oper erti ties es of of jet jet grou grouted ted so soilil is is much much like that of sedimentary rocks (e.g. mudstone, siltstone, sandstone depending of soil jet grouted). • To unde unders rsta tand nd and and app apply ly jet jet gro grout utin ing g - Good Good unde understa rstandi nding ng of soils soils - Knowle Knowledge dge of basic basic flui fluid d mecha mechanics nics - Knowle Knowledge dge of basic basic mechani mechanical cal engine engineeri ering ng


JET GROUTING PROCESS GeoEng Co C onsultant nts s (S) Pte Ltd

Jet Grout Pile


Jet Grout Pile

Variants of Jet Grouting

• 3 basic variants – Single tube/fluid – Double tube / fluid – Triple tube / fluid At present, double tube system is most widely used in Singapore.


SINGLE,DOUBLE & TRIPLE FLUID/TUBE JET GROUTING


Typical Jet Grouting Parameters Singapore Experience Parameters

Unit

Single Tube

Double Tube

Triple Tube

Super J et

Flow Rates Water Jet

l/min

NA

NA

60 -120

NA

Grout Jet

l/min

60-70

60-200

80-160

600

cfm

NA

175-500

175-500

175-500

Water Jet

bars

NA

NA

350-400

NA

Grout Jet

bars

200-300

200-400

100-200

300-400

bars

NA

7 -12

7 -12

7 -12

W:C

0.9 0.9 - 1.4 1.4

0.9 0.9 - 1.4 1.4

0.8 0.8 - 1.0 1.0

2 - 2.5

Withdrawal Rate

min/m

varies

8 - 30

6 -1 2

16

Rotation Speed

rpm

5-10

5-10

8 -12

up to 2.5

up to 2.0

up to 4.5

Air Shroud Jet

Fluid pressures

Air Shroud Jet

Cement and Grout Water / cement

Lift ing Paramete Parameters rs

Size Size of Collum ns In Marine Clay


m

0.5 to 0.8

Jet Grouting • Diam Diamet eter er of colu column mns s for forme med d 1.0 1.0m m to to 4.5m 4.5m diameter • The The lar large ge diam diamet eter ers s are are form formed ed by high high grout flow. • Diam iameter eter of rods rods appr approx ox 90m 90mm to 120m 20mm


Believe • Stre Streng ngth th of Gr Grou outt co colu lumn mns s ca cann nnot ot be ascertained mathematically • Larg Large e dia diame mete ters rs = Lar Large ge pres pressu sure res s • Larg Large e pre press ssur ures es = Lar Large ge move moveme ment nts s • Larg Large e wall wall move moveme ment nts s = Dama Damage ge


Strength Design of Jet Grouted Marine Clay

• Most Most com commo monl nly y jet jet grou groute ted d soil soil in Sin Singa gapo pore re is is in marine clay. • Stre Strengt ngth h of of jet jet grout grouted ed marine marine clay clay can can be estima estimated ted by determining the various contents of clay soil, water and cement. • The The rela relativ tive e amoun amounts ts of of the the thre three e const constitu ituent ents s in the jet grout can be estimated by “mass balance”.

Refer: Lee Y. (1998) “ A Framework for the Design Singapor e Marin e Design of Jet Grout Piles in Singapore Singapore Clay ” ”. MEng Thesis, Civil Engineering, NUS. GeoEng Co C onsultant nts s (S) Pte Ltd

Believe • La Larg rge e dia diame mete ters rs = Lar Large ge pr pres essu sure res s • La Larg rge e pre press ssur ures es = Lar Large ge mo move veme ment nts s • La Larg rge e wa wallll mo move veme ment nts s = Da Dama mage ge • Stre Streng ngth th of Grou Groutt colu column mns s cann cannot ot be ascertained mathematically


Energy decay of submerged jets

PQ

no air shroud

air shrouded

Distance from nozzle


Jet Grouting • Wa Wate terr jet jet im impi pin nge on so soilil wa wallll.. • Po Pore re pr pres essur sure e inc incre rease ases s rap rapid idly ly in so soilil ma mass. ss. • Bond Bonds s bet betwe ween en soi soill par parti ticl cles es ov over ercom come e by by por pore e pressure. • Soi oill par parti ticl cle es disi disint nteg egra rate tes. s. • Ther Therefo efore re,, ease ease of di disi sint nteg egra ratio tion n dep depen ends ds on particle to particle bond.


High pressure water jet impact on marine clay sample : note the total disintegration i.e. no pieces of of intact clay (LeeYeong (LeeYeong 1998) GeoEng Co C onsultant nts s (S) Pte Ltd

WATER WATER JET “CUTS” SOIL (NOT PUSH) PUSH) GeoEng Co C onsultant nts s (S) Pte Ltd

CASE STUDY Diaphragm wall 1.2m thick Grout Grout thick thicknes ness s – 4m to 5m Cu= 300kPa E= 150 MPa

RL 103.5

Fill RL 86.5

RL 86.0 86.0 – JGP JGP top top

UMC F1/F2

LMC OA


RL 82.0 82.0 – JGP bottom bottom

TYPICAL SECTION

2


IW 3

IW 4

27th Dec 2007 IW 4

IW 3

2

Approx 6m width

Time v s Displacement Displacement 100

r e s t 0 e t n m e o m -100 0 n e i l c c l a -200 n p i s x i a d -300 M

30

60

-400

No of Days from 1st Dec IW 4


IW 3

90

27th Dec 2007 2

IW 4

IW 3

Approx 6m width

3rd Jan 2008


Inclinometer Records for IW3 and IW4

Tim Ti me v s Displa Displ acement cement Feb 1st

Jan 1st 100

r e s t t 0 e n m e o m-100 0 n e i l c c l a -200 n i p s -300 x i a d M

30

60

-400

No of days from fr om 1st 1st Dec Dec IW 4

IW 3

Introduction of relief wells GeoEng Co C onsultant nts s (S) Pte Ltd

7th Jan 2008 IW 3


IW 4

Inclinometer Records for IW3 and IW4

Time vs Displacement Feb 1st

Jan 1st 100

r e s t t 0 e n m e o m-100 0 n e i l c c a -200 n l i p x i s a d -300 M

30

60

-400

Time fr f r om 1st Dec IW 4

IW 3

Introduction of relief wells GeoEng Co C onsultant nts s (S) Pte Ltd

-400 400 -300 300 -200 200 -100 100

0

100 100 200 300 400

0

RL 103.5 5

10

Fill 15

RL 86.5

20

25 ) m (

RL 86.0 –

UMC

H 30 T P E D

F2

35

LMC

RL 82.0 –

40

45

OA

50

55

GeoEng Co C onsultant nts s (S) Pte Ltd 60

Typical wall movement mode

If annulus is not maintained

Discharge is minimised Causing increased ratio of soil to cement and water to cement

Drilling to the point Of Soil Improvement GeoEng Co C onsultant nts s (S) Pte Ltd

When soil improvement commen commence ce – slurry slurry is is discharged

Start of volume build up in cavity –causing heave or lateral disp

Flow of slurry out of casing


Jet Grouting • Grout out pr pressu essurres are are not not the the mai main n cau caus se of of wall movements. • Wall Wall move moveme ment nts s can can be be cont contro rolllled ed by allowing slurry to be discharged • Reli Relief ef well wells s at the the loca locati tion on of each each grou groutt point would be best • Cont Contro rolllled ed grou grouti ting ng volu volume me is requ requir ired ed


Jet Grouting • Avoid Avoid relie relieff wel wells ls away away from from the the poi point nt of installation • Reli Relief ef well wells s nee need d to to be be cle clean aned ed • If volu volume me of grou groutt is is mix mixed ed wit with h the the slur slurry ry,, the strength would be reduced • If prop proper er rel relief ief wells wells are are prov provid ided ed,, cha chanc nces es are the volume of cement can be reduced allowing some savings GeoEng Co C onsultant nts s (S) Pte Ltd

Grout Mixed Pile/ Deep Soil Mixing/ Deep Cement Mixing GeoEng Co C onsultant nts s (S) Pte Ltd

Grout Mix Pile



Grout Mix Pile




Grout Mix Pile


Grout Mix Pile

Grout Mix Pile



Typical three shaft system


Typical DSM/DCM/GMP parameters

• Single – double- triple-quadruple sh shafts • Diam Diamete eterr of of col colum umns ns up to 2000 2000mm mm per per sha shaft ft – leading to approx 3.5m2 treated area per 4 shaft configuration (0.8m per shaft) • Stre trengths up up to 1MPa in MC • Can Can be be use used d for for stif stifff soi soils ls – depe depend ndin ing g on on the the machine torque • Pres Pressur sures es appl applie ied d are are slig slightl htly y hig highe herr tha than n tha thatt required to over come the overburden pressures GeoEng Co C onsultant nts s (S) Pte Ltd

Typical DSM/DCM layout - four shafts




Enhanced GMP/ Jet & Mechanical Mixing

Enhanced GMP/JMM • Sim imililar ar to GM GMP P/D /DS SM/ M/D DCM • With With th the e addi additi tion on of of a jet jet noz nozzl zle e to ca cate terr for for larger diameter • A cro cross ss be betw twee een n the the je jett gro grout ut me meth thod od an and d the GMP/DSM/DCM methods • Us Used ed fo forr wid wide e ran range ged d of of soi soill typ types es



Jet Mechanical Mixing




TYPICAL EGMP/JMM LAYOUT

Diameter by Jet pressure Blade diameter


Concerns of grouting -DCM/DSM/EGMP/JMM sign gn Stage tage – • Desi – – Strength and Stiffness – Performance of grouting grouti ng methods – Behaviour of Earth Retaining Structures Structu res during Excavation

• Cons onstru truct ction ion Sta Stage ge – – – Quality of grout cores – Properties of soils which have been disturbed di sturbed – Heave and lateral movements mo vements of the Earth Retaining Structures GeoEng Co C onsultant nts s (S) Pte Ltd

Change of soil properties due to Deep Mixing Methods

CPT-1

QC (Mpa)

GL

0 0 1 2 3 4

Fill

5 6 7 8 9

UMC

) m ( h t p e D

10 11 12 13

F2

14

LMC

15 16 17

OA

18 19 20 21


2

4

6

8

10

Change of soil properties due to Deep Mixing Methods

CPT-5

QC (Mpa)

GL

0 0

2

Fill

4

6

8

MC

) m (

10

h t p e D

12

14

16

18

OA


20

5

10

15

20

25

DSM/DCM • Meth Method od of grou grouti ting ng can can caus cause e dist distur urba banc nce e to existing soil layers. • Wall Wall move moveme ment nts s coul could d be be larg larger er than than predicted if the lower strengths are not considered • Cont Contro rolle lled d gro grout uting ing at the the upp upper er laye layers rs may be required


DSM/DCM • More More analy analysi sis s and and test tests s req requi uire red d to to understand the sensitivity of the various grouting methods • Wall Wall stif stiffn fnes ess s may may be a var varia iati tion on that that needs to be considered • Mixi Mixing ng of soft soft clay clays s can can caus cause e it it to be remo remoul ulde ded d – sens sensit itiv ivit ity y of of Sin Singa gapo pore re Marine Clay is about 5. GeoEng Co C onsultant nts s (S) Pte Ltd

Concerns of grouting • Desi sign gn Stage tage – – – Str tre engt ngth h and Stiffness Stiff ness – Performance of grouting grouti ng methods – Behaviour of Earth Retaining Structures Structu res during Excavation

• Cons onstru truct ction ion Sta Stage ge – – – Quality of grouting cores – Heave and lateral movements mo vements of the Earth Retaining Structures – Performance of Earth Retaining Retain ing Structures during Excavation GeoEng Co C onsultant nts s (S) Pte Ltd

Corr orre ela lati tion on of o f SP SPT ‘N ‘N’’ wi with th UCS or Cu Cu

• Occa Occasi sion onal ally ly we see see CPT CPT as a tes testt requirement. • CPT CPT can can only only pro provi vide de the the det deter ermi mina nati tion on of the top of grout layer – • Stre Streng ngth th of soil soil imp impro rove veme ment nt not not obtainable


Corr orre ela lati tion on of o f SP SPT ‘N ‘N’’ wi with th UCS or Cu Cu

• Very Very ofte often n we we see see SPT SPT and and Cori Coring ng test tests s to to be carried out in specifications • Core Core stre streng ngth th is comm common only ly ment mentio ione ned d but but not not ‘N’ ‘N’ value value to achie achieve ve • So con consu sult ltan ants ts/c /con ontr trac acto tors rs tre treat at it it as clay clay and use Cu= 5-6N • So to achi achiev eve e 300k 300kPa Pa,, we we need need nea nearl rly y SPT ‘N of 50 to 60 GeoEng Co C onsultant nts s (S) Pte Ltd

Cor orre rela lati tion on of o f SP SPT ‘N ‘N’’ wi with th UCS or Cu Plot of Cu to SPT 'N' Values Values of Jet Grouted Grouted Areas Areas 3

) 2 2.7 m m / 2.4 N ( u C 2.1 , h t g 1.8 n e r 1.5 t S r a 1.2 e h S 0.9 d e n 0.6 i a r d 0.3 n U

y = 0.0167x

0 0

20

40

60

SPT SPT 'N' Valu e


80

100

12 0

Correl Cor relati ation on of of SPT SPT ‘N’ ‘N’ wit with h UCS UCS or Cu • More More data data and and sta statis tisti tical cal anal analys ysis is need needed ed to be carried out to allow a better representation of SPT ‘N’ • SPT ‘N’ ‘N’ and and cori coring ng meth method ods s of obta obtain inin ing g strength have their own pit falls and data should be carefully analysed. • Care Care has has to to be be tak taken en to ensu ensure re that that the the soil soil type type is considered in any analytical model


Discussions • Grou Grouti ting ng of of soil soils s is still still cons consid ider ered ed an an Art Art as opposed to being a science • Grou Grouti ting ng in soil soils s see seems ms to be stil stilll the the domain of specialist sub contractors • Cons Consult ultan ants ts alwa always ys woul would d like like to leav leave e the the issues to the contractors GeoEng Co C onsultant nts s (S) Pte Ltd

Discussions • More More rese resear arch ch and and con consci scien enti tiou ous s gro grout utin ing g wor works ks is still required for more systematic grouting procedures to be developed • Jet Jet gro grouti uting ng is know known n to to cau cause se move moveme ment nts s to to earth retaining retaining structures structures – if not not done done correct correctly ly • soil soil mixi mixing ng meth method ods s rem remou ould lds s the the upp upper er soil soil layers and causes strength reduction and needs to be considered at design stage GeoEng Co C onsultant nts s (S) Pte Ltd

Moving Forward • More More need needs s to to be be don done e to to mit mitig igat ate e movements caused by JGP. This has to be part of the MS and trial test process • Pres Presen entt Adv Advis isor ory y not notes es requ requir ire e cri criti tica call control levels to be developed for grouting. How do we do that if we are unsure of the process? GeoEng Co C onsultant nts s (S) Pte Ltd

Moving Forward • For For all all gro grout utin ing g met metho hods ds,, more more data data collection still required for a better understanding of grouting strengths etc. • Cont Contra ract ctor ors s and and Cons Consul ulta tant nts s nee need d to to wor work k more closely to have a better understanding of the grouting methods


Th an k y o u


Concerns on Grouting in Soils

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