OEDOMETER TEST

KAEA3233 SOIL MECHANICS II SM1 OEDOMETER TEST GROUP 1

Name MUHAMMAD A!REEN "IN SI#EMAT MOHAMMED HA!IMIN "IN SALAM MOHAMMAD IR&AN "IN GA!ALI MOHAMMAD ASNA&I "IN AMIRUDDIN NUR LI)ANA "T HASSAN

INTRODUCTION

Matrices No. KEA11$$2% KEA11$$22 KEA12$$2' KEA12$$2( KEA12$$*$

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Consolidation of soft soil is the process of dissipation of excess pore water pressure in a row of time. When a surcharge is applied to saturated compressive soil, excess pore water pressure is built up causing an increase in pore water pressure. Due to the higher incompress incompressible ible behavior of pore water compared to soil, the excess pore water will initially initially carry the load. After some time, the drainage path opens and water starts moving from region of higher pressure to the region of lower pressure. Since dissipation of pore water pressure occurs simultaneously with the squeeing out of the pore water, then pore water pressure begins to decrease linearly linearl y or non!linearly. Afterwards the load will be transferred to the soil s"eleton and compression occurs resulting in decreased volume of the soil mass. #his phenomenon is called consolidation of soil. Consolidation of soil will cause downwards displacement of buildings or ground structures that may destroy utilities and ris" lives. $edometer test is a "ind of geotechnical investigation performed in geotechnical engineering that is used to determine the magnitude and rate of consolidation of saturated soil specimen. #he soil specimen is extruded into the consolidation ring and set up in the oedometer apparatus before it is sub%ected to one dimensional consolidation pressure. &ertical drainage is allowed at top and bottom of the specimen. #he test is performed by applying different loads to a soil sample and measuring the deformation response. #he results with a sufficient number of data points are determined to describe the relationship between void ratio and effective stress for a soil. #he parts of oedometer apparatus are shown in picture below.



A stress!void ratio graph 'e!log p curve( is plotted in a semi!logarithmic scale as shown below.

We can also determine the Swelling )ndex 'C s(, Compression )ndex 'C c( and Coefficient of &olume Compressib Compressibility ility 'mv(. #h #hee coef coeffic ficie ient nt of cons consol olid idati ation on 'Cv( and and the rat rate of consolidation can also be measured using the results of thic"ness changes of sample against time during a load step. #hen, we will be able to predict how a soil in the field will deform in response to a change in effective stress.



O"#ECTI+ES

During this laboratory we will learn about* •

$ne dimensional consolidation equipment

•

Consolidation behavior of cohesive soils

•

#o determine the compression index 'C c(, swelling index 'C s( and coefficient of permeability '" v(

PREPARATION O THE SOIL SPECIMEN OR THE TESTS

#he diameter, height and weight of the consolidation ring are measured. #he consolidation ring is then lubricated with silicon grease. #he soil specimen is extruded to the consolidation ring from the sampling sampling tube. #he cutting wire is used to cut the soil sample upon extrusion. extrusion. +xcess soil sample from the extrusion is tested for its moisture content. PROCEDURE

With the lower porous disc located centrally on the base of the cell, the consolidation ring and specimen 'cutting edge upper most( are lowered centrally on to the disc. #he ring retainer and cell body are fitted around the ring so that it is securely held and the fixing nuts are tightened progressively. )n some types of cell, the body itself acts as the ring retainer. #he upper porous disc is placed centrally on top of the specimen, chec"ing that the clearance is equal all round. #he spigot is located on the loading cap into the recess into the upper disc, so that the caps fit centrally.



Weights Weights are added to the load hanger to give the required pressure of , -, /, 0//, -//, 1//, 2//, 0// and 3-// "4a. 5owever the initial applied pressure is dependent on the softness of the soil. )n the test, the initial pressure pressure of - "4a is applied applied and the weight weight is placed carefully carefully on the load hanger. 6ill in water into the soil after - minutes. #he settlement readings are then ta"en at time of /, 0/, -/, 3/, 1/, /s 7 0, -, 1, 2, 0, 3/ min 7 0, -, 1, 2, -1 hours. After -1 hours, the weight is added and the quantity of weight must be twice more than the previously applied weight. 8nloading* After the maximum loading is applied on the soil and all the settlement readings are recorded, unloading should ta"e place not all at once but in a series of decrements. 8sual practice is to unload and allow swelling in about half the number of stages as were applied during consolidation, with not less than two loading stages. 9efore ta"ing off any weight from the hanger, the cloc" is set to ero, and the beam support is winded up so that it %ust touches the beam. #he beam is held down firmly against the support while the weights are removed: this requires a second person, except when only small weights are being removed. #he dial gauge is chec"ed so that it shows little or no movement. #he beam is released, and at the same instant the cloc" is started. #here is no need to wind down the wind support because the beam will rise as the specimen swells. #he upper loading cap is ensured to be remained covered with water. ;eadings of the compression gauge are ta"en exactly as the consolidation stages. After unloading, a specimen of the tested soil is ta"en for moisture content test in drying oven at 0/
a. #v = cv.t>'5>-(- at ?/@ and /@ degree of consolidation, with the corresponding time factor, #v = /.212 and /.0? respectively. b. With the use of #aylor #aylor and Berchant method '0?1/(, c v = /.212'5>-( ->t?/ where 5 is the specimen height c. With With the use of Casa Casagr gran ande de 'log 'log time time(( meth method od c = /.0?'5>-(->t/ where 5 is the



d. Calculate Calculate the coefficient coefficient of volume volume compressib compressibility ility,, mv mv = 'e>p(0>'0Ee/((F = 5>'5/.p( where, e = change in void ratio eo = initial void ratio 5 = Change in specimen height 5/ = )nitial height of the specimen p = Goad increment '"H>m -( e. 4lot the the void ratio ratio versus versus the logarith logarithmic mic of pressur pressuree 'e!log p curve(. curve(. #hen determin determinee the compression and swelling indexes 'C / and Cs( f. Calcula Calculate te the the coeffi coefficien cientt of perm permeabi eability lity,, " v " v = cv.mv.Iw RESULT ROM E,PERIMENT

Jeneral data Bass of the ring E glass plate = 0.0 g Bass of specimen E ring = 01. g Bass of soil specimen = . g )nside diameter of the ring = 12. mm 5eight of specimen, 5 i = -/ mm Area of specimen, A = 023 mm - = 02.3 cm Specific gravity of solids, J s = -.





Bass of wet specimen = -./ g Bass of can E dry soil = 0-2.// g Bass of dry specimen, B s = . g 6inal moisture content of specimen, w f = =

72.50 – 56.5 56.5

x 100 =28.32

CALCULATIONS

Bass of dry specimen after test, B s = . g Bass of water in specimen after test, B wf = = wf x x Bs= /.-23- x . = 0.// g 5eight of solids, 5 s =

Ms A x Gs x ρw

56.5

=

−3 1863 x 2.7 x 1 x 10

= 00.-3 mm

'same before and after test and note K w = 0 g>cm3( Ms

Dry density before test, K d =

Hi x A

56.5

=

20.00 x 1863

=1.516 g>mm3





Da- 1 2* /o0rs Loa 245

#ime 's(

Dial gauge '/.//0 mm(

/ 0/ -/ 3/ 1/ / / 0-/ -1/ 12/ ?// 02// 3// 21//

/.?3 /./ /.0/.02 /.-/.- /.-? /.12 /.0 /.2/3 /.23 /.2 /.2/.23

Consolidation pressure =

force area

#otal #o tal settlement = /.23mm

=

mg πd ² / 4

=

2 × 9.81 1.863 × 10

−3

= 0/.3 "H>m -





1/ / / 0-/ -1/ 12/ ?// 02// 3// 21//

0.00/ 0.001 0.002 0.01 0.022 0.-3/ 0.-11 0.-0 0.- 0.-/


force area

#otal #o tal Settlement = 0.-/ mm

Da- 3 %2 /o0rs Loa ( 45

#ime's( / 0/ -/ 3/ 1/

Dial Jauge 'mm( 0.10/ 0.110 0.10.12 0 13

=

mg πd ² / 4

=

4 × 9.81 −3 1.863 × 10

= -0./ "H>m-






force area

mg

=

πd

2

=

4

8 × 9.81 1.863 × 10

−3

= 1-.03 "H>m-

#otal #o tal Settlement = 0./? mm

U67oa *45

#ime 's 's(

Dial ga gauge '/ '/.//0 mm(

//

0.-11


force area

=

mg πd ² / 4

=

4 × 9.81 1.863 × 10

−3

Loa 245

#ime 's(

Dial gauge '/.//0 mm(

//

0.--1

force

mg

2 × 9.81

= -0./ "H>m -





Loa 245

Taylor's (Root ( Root Time) Graph 0.00 0.65

0.7

0.75

Dial gauge readings (m (mm) m) 0.8

0.85

0.9

5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00







0.848

Cv =

( ) H

2

2

t 90

0.848

=

(

20

−0.873 2

)²

27.04

= -.22 mm>min

×

1440 x 365 6

10

= /.02 m ² >year Loa 245

Casagandre (Log Time) Graph 0.10 0.65

10.00

1000.00

100000.00







t/ = 1.1 min 0.197

Cv =

0.197

=

H

(

2

)²

t 50

(

20

−0.873 2

)²

4.4

= 1./? mm>min

×

1440 x 365 6

10

= /.-0- m ² >year

Loa *45

Taylor's (Root ( Root Time) Graph







6rom #aylorLs #aylorLs ';oot time( graph, M#?/ = 1.0 min #?/ = 0.20 min 0.848

Cv =

( )

2

2

t 90

0.848

=

H

(

20.00

−1.26

2

)²

16.81

= 1.1-? mm>min

×

= /.-33 m ² >year

1440 x 365 6

10








10.00

1000.00

1

1.05

1.1

Dial gauge readings (mm) 1.15

1.2

1.25

1.3

T (min)

100000.00







Loa (45

Taylo T aylor's r's (R (Root oot Time) Time) Graph 0.00 0.0 0 5. 5.00 00 10 10.0 .0015. 015.0020 0020.0 .0025. 025.0030 0030.0 .0035. 035.0040 0040.00 .00 1.3 1.35 1.4 1.45

!ial "a#"e rea$i"s (mm) 1.5 1.55 1.6 1.65

√T (mi)









= .? mm>min

= /.10? m

²

×

1440 x 365 6

10

>year

Loa (45


10.00

1000.00

100000.00









0.197

Cv =

0.197

=

H

(

2

)²

t 50

(

20

−1.609 2

)²

3.4

= 1.2?? mm>min

×

= /.- m ² >year

1440 x 365 6

10









+oi Ratio ∆e

∆ H H S

=

H − H S

=

H S

&oid ratio, e = e / ! ∆ e e/

=

H 0 − H S H S

= '-/.// O 00.-3( > 00.-3 = /.20 6or -"g load, 0/.3 "4a ∆e

= /.23 > 00.-3 = /./2









= e/ ! ∆ e

e

= /.20 O /.000 = /./

6or -"g 'unloading(, 0/.3 "4a ∆e

= 0.--1 > 00.-3 = /.0/?

e

= e/ ! ∆ e = /.20 O /.0/? = /.-









Graph o% &oi$ Ratio a"aist o"  0.42 0.4 0.38

&oi$ Ratiio e

0.36 0.34 0.32











DISCUSSIO *osoli$atio is a metho$olo"y +y ,hi-h soils $imiish i ol#me.











;rom the eperimet ,e hae #se$ seeral loa$s to o#r spe-ime i or$er to o+tai the re<#ire$ set o% "a#"e to plot the "raphs. =y o,i" the al#es o% oi$ ratio a$ -osoli$atio press#re the "raphs o% e>lo" p ,as $ra,.  $etermii" the al#es o% *   *asa"ra$e metho$ a$ Taylor T aylor metho$ are are #se$. *asa"ra$e?s step o% $etermii" * 











P2 P1

¿ ¿

log ¿











The "reatess o% the -ota-t settlemet relies o #po the a$apta+ility o% the esta+lishmet a$ the sort s ort o% soil. ;or sa$y soils ,hi-h are are pr pro% o%o# o#$ $ly ly pee peetr tra+ a+le le o por pore ,ei" ,ei"ht ht $ee $eelo lope pe$ $ ,he ,he ai aiet ety y i-remets. The pore ,ater $eplete$ a,ay <#i-ly. ;lei+le settlemet a$ a$ -os -osol oli$ i$at atio io  happ happe e all all the the ,hil ,hile. e. ;or -lay -layey ey soil soils s ,hi,hi-h h are are e-e e-ept ptio ioa all lly y impe imperrmea+ mea+le le por pore ,ei" ,ei"ht ht is $ee $eelo lope pe$ $ ,he ,he ai aiet ety y i-remets. Ho prompt pore ,ater $epleti" e$lessly. e$lessly. t ,ill set asi$e ay











#$er hi"her +#r$e +ri"i" o the settlemet i the eamiatio ot all that sel%>ei$et. sel%>ei$et.

eepi" i mi$ the e$ "oal to $e-rease the lapses happee$ i the eperimet there are %e, steps sho#l$ +e tae. ;irstly maitai a strate"i- $ista-e %rom paralla mistae +y setti" the eye s#-h that the

OEDOMETER TEST

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