Advance Soil mechanics Present by Mr. Sieng PEOU

Master science of geotechnical engineering

Soils particle size

19.5mm>d>4.76mm.

Gravel

4.76mm>d>0.075mm

Sand

Coarse grained soils

0.075mm>d>0.002mm

Silt

d

Sieve analysis method

For coarse grained soils

Retained cumulative

%R= %100

.

..

weighttotal

cumulativeretainedweight

Passing cumulative

%P = 100-%R

Logarithm scale

Logd

0.001 0.01 0.1 1 10 100

a

If 0.001

Hydrometer analysis

For fine grained soils

Hydrometer analysis

%100*%SW

RRaP +=

TLKD =

P%-passing cumulative

a- soil factor

R-hydrometer reading

R-corrected factor

Ws-weight of dry soil

D-soil diameter

K-hydrometer factor

L-depth of hydrometer in

Solution

time in minute

Soil particle size curve Uniformity coefficient UC=D60/D10

d10 d60

Weight and volume relation ship

V

Va

Vw

Vs

W

Wa=0

Ww

Ws

W=Ws+Ww

V=Va+Vw+Vs

Vv =Va+Vw

V= Vv+Vs

Soils sampling Disturbed sample for determine properties

physics of soils Undisturbed sample for determine

properties mechanics of soils, we call undisturbed when AR(%)

Soils unit weight Natural water content:

Bulk unit weight:=

Dry unit weight: d=

Unit weight of particle solid: s=

ws

e

eSGVW

+

+=

1

s

s

VW

1001

+

=

VW s

%100=s

w

WW

Another parameter Void ratio:

Degree of saturation:

Saturated unit weight:

Effective unit weight:

d

ds

s

v

VV

e

==

w

s

v

w

eVVS

== %100

Ws

sate

eG

+

+=

1

ws

wsate

G

+

==

11

'

Another parameters Specific gravity:

Relative density:

Saturated water content:

ws

ss V

WG

=

%100minmax

max

=

ee

eeDR

%10011

= w

sdsat

Typical values of unit weight of soils

Soil type sat(KN/M3) d(KN/M3)

Gravel 20 to 22 15 to 17

Sand 18 to 20 13 to 16

Silt 18 to 20 14 to 18

Clay 16 to 22 14 to 21

Description based on Relative density

DR(%) Description 0 to 15 Very loose 15 to 35 Loose

35 to 65 Medium dense 65 to 85 Dense

85 to 100 Very dense

Soil consistence

ShrinkagelimitWs

PlasticlimitWp

LiquidlimitWL

Atterberglimit

State of cohesion soils Plastic index IP=WL-WP

Liquidity index IL=

P

P

I

State of cohesion soils

If 0

CH

MH CL

ML

CL-ML

Soil classification USCS:Unified soil classification system

(ASTM Test Designation D-2487) ASTM: American Society for Testing and Materials Proposed by Casagrande in 1942,this system was revised in 1952 by U.S Bureau of Reclamation.

Coarse grained soils

%R(4.76mm)>0.5%R(0.075mm)Gravel

%R(4.76mm)50%Coarse grained soils

Gravel

UC4Well graded Gravel

GW

Clean Gravel%P(0.075mm)

Gravel

Located CL or CHPoorly gradedclayey Gravel

GC-GP

Located ML or MHPoorly graded silty Gravel

GM-GP

Located CL-MLPoorly graded clayey

silty GravelGC-GM-GP

UC4On plastic Chart Casagrande

Mixed Gravel5%

Gravel

Located CL or CHclayey Gravel

GC

Located ML or MH silty Gravel

GM

Located CL-ML clayey silty Gravel

GC-GM

Mixed Gravel%P(0.075mm)>12%

Sand

UC6Well graded Sand

SW

Clean Sand%P(0.075mm)

Sand

Located CL or CHPoorly gradedclayey Sand

SC-SP

Located ML or MHPoorly graded

silty SandSM-SP

Located CL-MLPoorly graded clayey

silty SandSC-SM-SP

UC6On plastic Chart Casagrande

Mixed Sand5%

Sand

Located CL or CHclayey Sand

SC

Located ML or MH silty Sand

SM

Located CL-ML clayey silty Sand

SC-SM

Mixed Sand%P(0.075mm)>12%

Fine grained soils

CL CH

For Clay

ML MH

For Silt

CL-ML

For Silty clay

%R(0.075mm)

Lean Clay(CL)

%S>%GLean ClayWith sand

%S

Fat Clay(CH)

%S>%GFat Clay

With sand

%S

Silt (ML)

%S>%GSilt

With sand

%S

Elastic Silt (MH)

%S>%GElastic SiltWith sand

%S

Silty clay (CL-ML)

%S>%GSilty clay

With sand

%S

Soil classification AASHTO:Association American for

State Highway and Transportation official, was developed 1929 and proposed by the committee on Materials for sub grades and Granularity Type Boards of the Highway Research Road in 1945(ASTM Test designation D-3282;AASHTO method M145)

Granular Materials %P(0.075mm)

Silty - clay material %P(0.075mm)>35% Group classification A-4 A-5

A-6

A-7 A-7-5 A-7-6

%P(2mm) %P(0.425mm) %P(0.075mm) >35% >35% >35%

>35%

WL 40 40 IP 10 Usual type of materials

Silty soils Clayey soils

General subgrade rating

Fair to poor

For A-7-5: IPWL-30

Group index GI

GI=(%P(0.075)-35)[0.2+0.005(WL-40)]+0.01(%P(0.075)-15)(IP-10)

Soil compaction Standard Proctor test

Modified Proctor test

Specification for standard Proctor test(based on ASTM test designation 698-91)

Item Method A Method B Method C Diameter of mold 101.6mm 101.6mm 152.4mm

Volume of mold 943.3cm3 943.3cm3 2124cm3 Weight of hammer 24.4 N 24.4 N 24.4 N Height of hammer drop 304.8mm 304.8mm 304.8mm Number of hammer blows per layer

25 25 56

Number of layer of compaction

3 3 3

Energy of compaction 591.3KNm/m3 591.3KNm/m3 591.3KNm/m3 Soil to be used %R(4.75)20% %R(9.5)20% %R(19)

Specification for modified Proctor test(based on ASTM test designation 1557-91)

Item Method A Method B Method C Diameter of mold 101.6mm 101.6mm 152.4mm

Volume of mold 943.3cm3 943.3cm3 2124cm3 Weight of hammer 44.5 N 44.5 N 44.5 N Height of hammer drop 457.2mm 457.2mm 457.2mm Number of hammer blows per layer

25 25 56

Number of layer of compaction

5 5 5

Energy of compaction 2696KNm/m3 2696KNm/m3 2696KNm/m3 Soil to be used %R(4.75)20% %R(9.5)20% %R(19)

Compaction equipment

Compaction curve MOISTURE DENSITY RELATIONSHIP CURVE

1.900

2.000

2.100

2.200

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

Moisture content %

D

r

y

D

e

n

s

i

t

y

g

/

m

3

Wopt

dmax

California Bearing Ratio(CBR) For study the strength of soils after

compacting in optimum state. 1-Recompaction the soil in optimum

state 2-Determine CBR in dry condition 3-Saturated the soil under water 4 days 4-Determine CBR in soaked condition CBR=

%100..standard

..

loadunit

loadunitTest

BEARING RATIO TEST (CBR)

Project: Pochentong Airport Job No.Location of Project: Pochentong Airport Boring No 2 Sample No.2Description of Soil: Tested by: Mr. Men Tharith Date of Testing. 16/05/2002

CBR Test Load Data (soaked)Mold

Surrcharge Piston load Load.

Penetration. dial reading kgf/cm2

mm ( unit )0.000 0 01.00 0.045 2.30772.00 0.075 3.84623.00 0.11 5.6414.00 0.145 7.43595.00 0.175 8.97446.00 0.21 10.7697.00 0.25 12.8218.00 0.28 14.3599.00 0.31 15.89710.00 0.34 17.436

CBR(2.54)= 7.1429

Acceppted CBR= 7.14

Final water Top 7.9conten, w% Midle 7.8

(soaked) Bottom 7.99sample Averagee 7.8967

Wet unit wt. = 2.2952 g/cm3 Dry unit wt. = 2.13444 g/cm3

Wet unit wt.(soaked) = 2.303 g/cm3

Curve CBR Test

0

2

4

6

8

10

12

14

16

18

20

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

Renetration (mm)

L

o

a

d

(

k

g

f

/

c

m

2

)

P2.54

Penetration(mm) Standard unit load(Mpa)

2.5 6.9

5 10.3

7.5 13

10 16

12.7 18

CBR equipment

CBR equipment

CBR special for field control Compaction the soils in optimum state

with different energy 1-Compaction 10 blows per layer and

saturated the soil under water during 4 days

2-Compaction 25 blows per layer and saturated the soil under water during 4 days

3-Compaction 55 blows per layer and saturated the soil under water during 4 days

4-Determine CBR in soaked condition for

CBR chart

CBR General rating

Uses Classification system

USCS AASHTO

0-3 Very poor

Subgrade

OH,CH,MH,OL

A5,A6,A7

3-7 Poor to fair

Subgrade

OH,CH,MH,OL

A4,A5,A6,A7

7-20 Fair Subbase OL,CL,ML,SC,SM,SP

A2,A4,A6,A7

20-50 Good Base subbase

GM,GC,SW, SM,SP,GP

A1b,A2-5, A3,A2-6

>50 Excellent

Base GW,GM A1-a,A2-4 A3

Control soils compaction

%Compaction=

Determine field density by using:

1-Undisturbed sampling 2-Sand cone method 3-Balloon density equipment 4-Nuclear method

max

.

%100

d

fieldd

Sand cone method

Control CBR Field CBR By using Dynamic cone penetration test DCP

1-Kleyn and Van Heerden(600cone) : Lg.(CBR)=2.632-1.28Lg.(mm/blow)

2-Smith and Pratt (300cone) : Lg.(CBR)=2.555-1.145Lg.(mm/blow)

3-VanVuuren (300 cone) : Lg.(CBR)=2.503-1.15Lg.(mm/blow)

4-TRRL Road Note 8(600cone) : Lg.(CBR)=2.48-1.057Lg(mm/blow)

CBR control

Shear strength of soils Total Stress Analysis (TSA) -for clayey soils with permeability very low,

so for short term loading soils and water work together.

Effective Stress Analysis(ESA) -for sandy soils with high permeability,so for

short term loading soils work yourself only For analyze soils stability

problems(bearing capacity,slope stability,lateral pressure on earth-retaining structure)

Effective stress in soils mass

Total stress 0= sat.Z Effective stress 0= .Z Pore water pressure U= w.Z = sat- w w unit weight of water

Mohr-Coulomb Criteria The shear stress on the failure plan

as a linear function of the normal stress (Coulomb,1776)

= c + tg A material fails because of a critical

combination of normal stress and shear stress, and not from either maximum normal or shear stress alone (Mohr,1900)

Failure plan x

y

f

= 45+/2

Mohr-Coulomb failure criteria

C

Line Coulombs: = .tg+C

Unconfined compression test Type TSA test Undisturbed sample with

h0=2do Speed =2%/min =2%/min=h/h0*100%/min

For determine undrained cohesion Cu, in this case u=0

qu

Mohr circle

0 qu

Cu

Direct shear test Type undrained

test or drained test

Undisturbed sample

For determine cohesion of soils C and internal friction angle of soils

Build by Casagrande

Shear box Porous stone

Shear force

Shear box

Normal force

Porous stone

Loading plate

Soil sample

Determine C &

( )22)(

ii

iiii

n

ntg

=

n

tgC ii =

C

0

Triaxial test

UU test: Unconsolidated undrained test

CU test: Consolidated undrained test

CD test: Consolidated drained test

Triaxial equipment

UU test

0 0 qu Cu

General relationship of consistency and unconfined compression strength of clay

Consistency qu(KN/m2) Very soft 0-25

Soft 25-50 Medium stiff 50-100

Stiff 100-200 Very stiff 200-400

hard >400

Empirical equation related to Cu and 0 Reference Relationship Remarks

Skempton (1957)

Cu=[0.11+0.0037.IP].0 Cu from vane shear test

For normally consolidated clay

Chandler(1988)

Cu=[0.11+0.0037.IP].c

Cu from vane shear test c preconsolidation pressure

Can be use for over consolidated clay not valid for sensitive clay

Jamiolkowski et al (1985)

Cu=[0.23 0.04].c

For lightly over consolidated

CU & CD test

0

C 3 1

Typical values of drained Angle of friction for Sand and Silt

Soil type (degree) Sand : Rounded grains

Loose 27-30 Medium dense 30-35 Dense 35-38

Sand : Angular grains Loose 30-35 Medium dense 35-40 Dense 40-45 Gravel with some sand 34-48 Silts 26-35

Typical values of drained Angle of friction and Cohesion for Gravel

USCS (degree) C(KN/m2) GW 40 5 0 GP 38 6 0 GM 36 4 0 GC 34 4 0

GM-ML 35 5 0 GM-GC 33 3 2 2 GC-CL 29 4 3 3 GC-CH 28 4 4 4

Typical values of drained Angle of friction and Cohesion for Sand

USCS (degree) C(KN/m2) SW 38 5 0 SP 36 6 0 SM 34 3 0 SC 32 4 0

SM-ML 34 3 0 SM-SC 31 3 5 5 SC-CL 28 4 5 5 SC-CH 27 3 10 10

Typical values of drained Angle of friction and Cohesion for Fine grained soils

USCS (degree) C(KN/m2) ML 33 4 0

CL-ML 30 4 15 10

CL 27 4 20 10

CH 22 4 25 10

OL 25 4 10 5

OH 22 4 10 5

MH 24 6 5 5

Stress in soils mass

O

M

Z

M1

Z

Q

2a=L

2b=B

Determine stress in soils mass 1-Stress at the center of footing vM=4.I2.q = 4.K.q

BLQq =

++

+++

++

++

+++

++=

112

12

112

41

2222

22

22

22

2222

22

2nmnm

nmmnarctg

nm

nm

nmnm

nmmnIpi

ZB

m2

=

ZL

n2

=

a

Z=

Determine stress in soils mass 2-Stress at the corner of footing vM1=I2.q = K.q

BLQq =

++

+++

++

++

+++

++=

112

12

112

41

2222

22

22

22

2222

22

2nmnm

nmmnarctg

nm

nm

nmnm

nmmnIpi

ZB

m =ZL

n =a

Z2

=

Determine stress in soil mass by using table b/a

K

0

0.1

0.2

1/3

0.4

0.5

2/3

1

1.5

2

2.5

3

5

10

0 0.000 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.250 0.2 0.000 0.137 0.204 0.234 0.240 0.244 0.247 0.249 0.249 0.249 0.249 0.249 0.249 0.249 0.249 0.4 0.000 0.076 0.136 0.187 0.202 0.218 0.231 0.240 0.243 0.244 0.244 0.244 0.244 0.244 0.244 0.5 0.000 0.061 0.113 0.164 0.181 0.200 0.218 0.232 0.238 0.239 0.240 0.240 0.240 0.240 0.240 0.6 0.000 0.051 0.096 0.143 0.161 0.182 0.204 0.223 0.231 0.233 0.234 0.234 0.234 0.234 0.234 0.8 0.000 0.037 0.071 0.111 0.127 0.148 0.173 0.200 0.214 0.218 0.219 0.220 0.220 0.220 0.220 1 0.000 0.028 0.055 0.087 0.101 0.120 0.145 0.175 0.194 0.200 0.202 0.203 0.204 0.205 0.205

1.2 0.000 0.022 0.043 0.069 0.081 0.098 0.121 0.152 0.173 0.182 0.185 0.187 0.189 0.189 0.189 1.4 0.000 0.018 0.035 0.056 0.066 0.080 0.101 0.131 0.154 0.164 0.169 0.171 0.174 0.174 0.174 1.5 0.000 0.016 0.031 0.051 0.060 0.073 0.092 0.121 0.145 0.156 0.161 0.164 0.166 0.167 0.167 1.6 0.000 0.014 0.028 0.046 0.055 0.067 0.085 0.112 0.136 0.148 0.154 0.157 0.160 0.160 0.160 1.8 0.000 0.012 0.024 0.039 0.046 0.056 0.072 0.097 0.121 0.133 0.140 0.143 0.147 0.148 0.148 2 0.000 0.010 0.020 0.033 0.039 0.048 0.061 0.084 0.107 0.120 0.127 0.131 0.136 0.137 0.137

2.5 0.000 0.007 0.013 0.022 0.027 0.033 0.043 0.060 0.080 0.093 0.101 0.106 0.113 0.115 0.115 3 0.000 0.005 0.010 0.016 0.019 0.024 0.031 0.045 0.061 0.073 0.081 0.087 0.096 0.099 0.099 4 0.000 0.003 0.006 0.009 0.011 0.014 0.019 0.027 0.038 0.048 0.055 0.060 0.071 0.076 0.076 5 0.000 0.002 0.004 0.006 0.007 0.009 0.012 0.018 0.026 0.033 0.039 0.043 0.055 0.061 0.062 10 0.000 0.000 0.001 0.002 0.002 0.002 0.003 0.005 0.007 0.009 0.011 0.013 0.020 0.028 0.032 15 0.000 0.000 0.000 0.001 0.001 0.001 0.001 0.002 0.003 0.004 0.005 0.006 0.010 0.016 0.021 20 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.001 0.002 0.002 0.003 0.004 0.006 0.010 0.016

50 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.002 0.006

Consolidation

Settlement of soils

hi

S

Ho

S

ho

Before loading After loading

Consolidation curve

e

Log

p 1 2 3 4

e1 e2

e3

e4

Determination parameter of consolidation

Natural void ratio

Void ratio after consolidation

Swell index

Compression index

0

00

HHh

e

=

0

00

HhHh

e ii

=

12

21

loglog

=

eeCs

34

43

loglog

=

eeCc

Determination parameter of consolidation

Modulus of elasticity

e and located between 100 Kpa to 200KPa

Compression index

Swell index

+=

e

emE ks 0

1.

Types of soil

emKuNsMBaF mk GaRsyeTAnwgemKuNes

Soil type RbePTdI

Sand xSac;/ l,ayxSac; 0.30 0.74

Silt l,aydI\d 0.35 0.62

Clay dI\d 0.42 0.40

Elastic parameter of various soils Type of soils Modulus of

elasticity Es(Mpa) Poissons ratio

s Loose sand 10-25 0.20-0.40 Medium dense sand

15-30 0.25-0.40

Dense sand 35-55 0.30-0.45 Silty sand 10-20 0.20-0.40 Sand and gravel 70-170 0.15-0.35 Soft clay 4-20

0.20-0.50 Medium stiff clay 20-40 Stiff clay 40-100

Coefficient of consolidation

Log t

h

t1

t1/4

t 100

100

0

50

t 50 1min

Determination coefficient of consolidation Coefficient of consolidation from Casagrande

method Cv[m2/s]

h0- initial thickness of sample Permeability coefficient

Coefficient of compressibility

Coefficient of volume change

50

2

197.0t

HC v = 2500

=

hH

e

aCK wvv+

=

1..

=

ea v

01 ea

m vv +=

Typical values of coefficient of consolidation Cv[cm2/s]

Liquid limit Lower limit of recompressio

n

Undisturbed virgin

compression

Upper limit remolded

30 3.5*10-2

5*10-3

1.2*10-3

60 3.5*10-3

1*10-3

3*10-4

100

4*10-4

2*10-4

1*10-4 Source U.S Navy 1962

In situ test

Static cone penetration test Dynamic cone penetration test DCP Standard penetration test Shear vane test Pocked penetration test

Static cone penetration test

K

c

NqCu 0=

+=

0'log38.01.0

cqArctg

E=2.qc

qc:cone resistance

Nk=20

Dynamic cone penetration test AHM

MMeMqd

.

.)'.( +=

qd :cone resistance

M:weight of hammer

M:weight of rods

A:cone area

H:height hammer falling

e:penetration for one blow

Standard penetration test

Index SPT N value is amount of blows for penetration split spoon sampler in soils 30 cm

N=N1+N2

Ncor= CN.Nfield

CN = 0.77log D.2000

Peck1974

0'

178.9

=NC Liao & Whihman 1986

0'01.012

+=NC Skempton1986

=

6.95'log25.11 0NC Seed 1975

For fine sand or silt saturated with N >15

Ncor=15+0.5 (Nfield-15)

Relationship of SPT and properties mechanics of soils

2020 += N Hatanaka & Uchida 1996 200054.03.01.27 NN += Wolff 1989

1518 += N For road and Bridges design sMrab;f;l;nigs

Relationship of SPT and properties mechanics of soils

Undrained cohesion Cu=K.N Stroud(1974)

3.5KPa

Soils type

N blows

DR %

degree

KN/m3

Very loose

0 4

0 15

< 28

11 16

Loose

4 10

15 35

28 30

14 18

Medium dense

10 30

35 65

30 36

17 20

Dense;

30 50

65 85

36 41

17 22

Very dense

> 50

85 100

> 41

20 23

Soils type

N

qu KPa

Very soft

< 2

< 25

Soft

2 4

25 50

Medium

4 8

50 100

Stiff

8 15

100 200

Very stiff

15 30

200 400

Hard

> 30

> 400

Thank you for your attention

Mr. Sieng PEOU Master science of

geotechnical engineering