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)
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