interfacial friction between soils and solid surfaces dr. r. g. robinson assistant professor...
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Interfacial friction between soils and
solid surfaces
Dr. R. G. RobinsonAssistant Professor
Department of Civil EngineeringIIT Madras
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Shallow foundation
Deep foundationTip resistance
Typical field situations
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Retaining walls
Typical field situations
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Reinforced earth walls
Typical field situations
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Geosynthetic reinforced earth slopes
Typical field situations
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Geotextiles
Typical field situations
www.geosyntheticssociety.org
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Definition of coefficient of friction and friction angle
Soil
Solid material
P
TP Normal Force
T Shear Force
Coefficient of friction,
=tan=T/P
where, is the friction angle
T
P
Normal stress=P/A
She
ar s
tres
s =
T/A
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Potyondy (1961) Rowe (1962) Silberman (1961)
Ingold (1984) Ingold (1984)
Apparatus used for evaluating friction angle
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Jewell and Wroth (1987) Murthy et al. (1993)
Coyle and Sulaiman (1967)
Apparatus used for evaluating friction angle
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Brumund and Leonards (1973) Ingold (1984)
Heerema (1979) Yoshimi and Kishida (1981)
Apparatus used for evaluating friction angle
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Desai et al. (1985) Uesugi and Kishida (1986)
Paikowsky et al. (1995) Abderrahim and Tisot (1993)
Apparatus used for evaluating friction angle
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Some TerminologiesSome Terminologies
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Three Phases in Soils
S : Solid Soil particle
W: Liquid Water
A: Air Air
Void ratio, e = Vv/Vs Water content, w = Mw/Ms
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Relative Density (DRelative Density (Drr))
Loosest Densest
100minmax
max
ee
eeDr
emax = 0.92 emin = 0.35
(Lambe and Whitman, 1979)
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Particle shapes-- SandParticle shapes-- Sand
Rounded Subrounded
Subangular Angular
Coarse-grained soils
(Holtz and Kovacs, 1981)
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ASTM D 4253; ASTM D 4254
Maximum and minimum void ratio
Maximum void ratioMinimum void ratio
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Direct shear testDirect shear test
tannf c
f shear strength of soiln Normal stressc cohesion intercept angle of internal friction
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n1 n2 n3Displacement
Displacement
Typical direct shear test results
n1
n2
n3
Angle of repose
cv
cv ~ Angle of repose
Dense sandLoose sand
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Interface friction in sandsInterface friction in sands
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Factors influencing interfacial friction angle of SandFactors influencing interfacial friction angle of Sand
Surface RoughnessSurface Roughness Density of sandDensity of sand Normal stressNormal stress Rate of deformationRate of deformation Size of apparatusSize of apparatus Grain size and shapeGrain size and shape Type of apparatusType of apparatus
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Influence of sand density and surface RoughnessInfluence of sand density and surface Roughness
0
0.25
0.5
0.75
1
1 10 100 1000Surface roughness, Rmax, m
/ c
v Steel Dr = 40%Steel Dr = 60%Steel Dr = 90%Brass Dr=65%Aluminium Dr=65%SteelWoodConcrete
Toyourasand
Soma sand
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Soil Type Soil Condition
Silica sand loose
dense
35
40
21
20
Calcareous sand from Guam
loose
dense
loose, crushed
loose, ground
dense, crushed
46
49
46
46
48
18
18
21
-
22
Calcareous sand from Florida
loose
medium
dense
medium, crushed
medium, ground
dense, crushed
44
45
47
45
45
49
20
20
23
23
-
23
Results of triaxial and soil-steel friction tests (after Noorany, 1985)
Influence of sand density……Influence of sand density……
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0.1
0.2
0.3
0.4
15 16 17 18
Sand density kN/m3
Co
eff
icie
nt
of
fric
tio
n,
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100
Relative Density (%)
tan
( o
r
)
Steel
Wood
Concrete
Sand
Influence of sand density……Influence of sand density……
Acar et al. 1982 Levacher and Sieffert 1984
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Limiting values ofLimiting values of
I Maximum Values:
Potyondy (1961), Panchanathan and Ramaswamy (1964), Uesugi and co-workers reported the limiting maximum value of is the peak angle of internal friction p
Yoshimi and Kishida (1981) report that the maximum limiting value is the critical state friction angle cv
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Interface Source
Sand-material
Sand-smooth surface
Sand-smooth material
Sand-normal glass
Sand-pyrex glass
Sand-stainless steel
Sand-steel
Sand-steel
Glass beads-steel
Material-Material
Diamond-diamond
Sapphire-sapphire
Metal-diamond
Steel-sapphire
0.5
7 - 10
5 – 6
7tan -1 (0.07/Ri) §
0.5
5
3
11
3
7
Lambe and Whitman (1969)
Yoshimi and Kishida (1981)
Tatsuoka and Haibara (1985)
Tatsuoka and Haibara (1985)
Tatsuoka and Haibara (1985)
Uesugi and kishida (1986b)
Tejchman and Wu (1995)
Paikowsky et al. (1995)
Bowden and tabor (1986)
Bowden and tabor (1986)
Bowden and tabor (1986)
Bowden and tabor (1986)
Notes: Particle-to particle friction angle
§ Ri Modified roundness
Minimum Values of Reported by Various Authors
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Influence of normal stressInfluence of normal stress
Potyondy (1961); Acar (1982): Both δ and Φ decreases with normal stress but the ratio (δ/) remains constant
Heerema (1979), Uesugi and Kishida (1986), O’Rourke et al. (1990) is independent of normal stress
For soft materials: increases with normal stress due to indentation of sand into the material (Panchanathan and Ramaswamy, 1964; Valsangkar and Holm (1997)
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Heerema (1979)Heerema (1979)– Rate of deformation from 0.7 to 600 mm/sRate of deformation from 0.7 to 600 mm/s– No influenceNo influence
Lemos (1986)Lemos (1986)– Rate of deformation 0.0038 to 133 mm/minRate of deformation 0.0038 to 133 mm/min– No influenceNo influence
Influence of Rate of deformationInfluence of Rate of deformation
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Brumund and Leonards (1973)Brumund and Leonards (1973)– Rods with interface area of 225 cmRods with interface area of 225 cm22 and 400 cm and 400 cm22
– No appreciable differenceNo appreciable difference Uesugi and kishida (1986)Uesugi and kishida (1986)
– Simple shear apparatus, 40 cm2 and 400 cmSimple shear apparatus, 40 cm2 and 400 cm22
– No influenceNo influence O’Rourke et al (1990)O’Rourke et al (1990)
– Direct shear apparatus of size equal to 6cm x 6 cm, 10 Direct shear apparatus of size equal to 6cm x 6 cm, 10 cm x10 cm, 28 cm x28 cm and 30.5x30.5 cmcm x10 cm, 28 cm x28 cm and 30.5x30.5 cm
– No significant influenceNo significant influence
Influence of Size of apparatusInfluence of Size of apparatus
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Influence of grain size and shapeInfluence of grain size and shape
Particle diameter (mm)
Fric
tion
an
gle
(deg
rees
) Rowe (1962)
Rowe (1962), Uesugi and Kishida (1986), Jardine and Lahane (1994):
decreases with increase in grain size
Angular particles give higher friction angle (Uesugi and Kishida 1986; O’Rourke et al. 1990; Paikowski et al. 1995)
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Kishida and Uesugi (1987)Kishida and Uesugi (1987)– Simple shear versus direct shearSimple shear versus direct shear– No differenceNo difference
Thandavamurthy (1990)Thandavamurthy (1990)– Direct shear versus model pile testsDirect shear versus model pile tests– Direct shear gives 20% higherDirect shear gives 20% higher
Abderrahim and Tisot (1993)Abderrahim and Tisot (1993)– Direct shear- Ring torsion-Pressuremeter probeDirect shear- Ring torsion-Pressuremeter probe– Direct shear > Pressuremeter probe >Ring shearDirect shear > Pressuremeter probe >Ring shear
Influence of type of apparatusInfluence of type of apparatus
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QUANTIFICATION OF INTERFACE ROUGHNESS
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versus Roughness (Bosscher and Ortiz 1987)
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Normalized Roughness (Kishida and Uesugi 1987)
50
50max )(
D
DLRRn
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Correlation with Normalized Roughness (Kishida &Uesugi 1987)
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2
31
1
42
2
1
l
rr
l
rrR
Modified roundness of a particle
Definition of modified roundness (Uesugi and Kishida 1986)
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Correlation between , Rn and R
(0.27)
(0.19)
(0.17)
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Author(s)Author(s) Type of testing apparatusType of testing apparatus Results of investigationResults of investigation
Potyondy (1961)Potyondy (1961) Direct shear apparatus Direct shear apparatus with the sand on the top with the sand on the top of test materialof test material
increases with density and increases with density and lim==pp
Broms (1963)Broms (1963) Direct shear mode by Direct shear mode by sliding the material over sliding the material over the sandthe sand
A A value of 23 value of 23oo was obtained was obtained irrespective of sand densityirrespective of sand density
Yoshimi and Yoshimi and Kishida (1981)Kishida (1981)
Ring shear with the test Ring shear with the test material on top of sandmaterial on top of sand
Density has no influence and Density has no influence and limlim==cvcv
Acar et al. (1982)Acar et al. (1982) Similar to PotyondySimilar to Potyondy increases with densityincreases with density
Noorany (1985)Noorany (1985) Similar to BromsSimilar to Broms Influence of density is negligibleInfluence of density is negligible
Uesugi et al. Uesugi et al. (1990)(1990)
Simple shear with the Simple shear with the sand on top of the test sand on top of the test materialmaterial
increases with density increases with density limlim==pp
Summary of some published interface friction tests
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Analysis of past studies
From the review the following three conclusions can be drawn:
(1) increases with surface roughness and reaches a maximum limiting value
(2) For very rough surfaces, tends to a limiting maximum value which could be either the peak angle of internal friction p or the critical state friction angle cv.
(3) can either increase or remain constant with the increase in sand density.
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Author(s)Author(s) Type of testing apparatusType of testing apparatus Results of investigationResults of investigation
Potyondy Potyondy (1961)(1961)
Direct shear apparatus Direct shear apparatus with the sand on the top with the sand on the top of test materialof test material
increases with density increases with density and and lim==pp
Broms (1963)Broms (1963) Direct shear mode by Direct shear mode by sliding the material over sliding the material over the sandthe sand
A A value of 23 value of 23oo was was obtained irrespective of obtained irrespective of sand densitysand density
Yoshimi and Yoshimi and Kishida (1981)Kishida (1981)
Ring shear with the test Ring shear with the test material on top of sandmaterial on top of sand
Density has no influence Density has no influence and and limlim==cvcv
Acar et al. Acar et al. (1982)(1982)
Similar to PotyondySimilar to Potyondy increases with densityincreases with density
Noorany Noorany (1985)(1985)
Similar to BromsSimilar to Broms Influence of density is Influence of density is negligiblenegligible
Uesugi et al. Uesugi et al. (1990)(1990)
Simple shear with the Simple shear with the sand on top of the test sand on top of the test materialmaterial
increases with density increases with density limlim==pp
Summary of some published interface friction tests
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Type A apparatus Type B apparatus
SAND SANDMaterial
Loading cap
Schematic of Type A and Type B apparatus
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Sl.No. Features Type A Type B
I Apparatus configuration
1
2
3
Relative position of
solid material and sand
and sample
preparation.
Application of normal
stress to the interface.
Apparatus type in
literature
Soild material is on the top of
sand. The sand specimen is
prepared first and the solid
surface is placed over the
prepared leveled surface.
Normal stress is applied through
the material to the interface.
Ring torsion apparatus, direct
shear apparatus by sliding solid
material over sand.
The sand specimen is
on the top of solid
material surface. The
sand is prepared
directly on the solid
surface.
Normal stress is
applied through the
sand the interface.
Direct shear apparatus
by sliding soil over solid
material, simple shear
apparatus, translational
test box etc.
Features of Type A and Type B apparatus
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Sl.No. Features Type A Type B
II Influence of type of apparatus on the results obtained
4
5
6
Influence of
roughness
Influence of
density of sand.
Maximum limiting
value of
increases with
roughness
Negligible.
The maximum limiting
value for very rough
interface is critical state of
angle of internal friction of
sand
increases with
roughness.
increases with
the increase of
density.
The limiting
maximum value is
the peak angle of
internal friction of
sand.
….. Features of Type A and Type B apparatus
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Experiments in Direct shear Experiments in Direct shear apparatusapparatus
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Solid materials used
Material 1– Stainless steel
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Material 2– Mild steel
Material 3– Mild steel
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Material 4– Ferrocement
Material 5– Ferrocement
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Surface profiles of the materials
Stainless steel
Mild steel
Concrete surface
Mild steel
Concrete surface
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Grain size distribution curves of the sands used
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Sand
No.
Gs D50
mm
Cu Dav
mm
(d)max
kN/m3
(d)min
kN/m3
1
2
3
4
5
6
7
2.64
2.64
2.64
2.64
2.65
2.64
2.65
1.60
1.10
0.74
0.42
0.27
0.78
2.20
1.3
1.3
1.5
1.4
1.6
3.4
8.3
1.53
1.01
0.69
0.41
0.27
1.10
1.92
15.9
16.0
16.1
16.0
16.2
18.0
18.6
13.0
12.9
13.1
13.0
13.0
14.0
14.5
Note:
Gs Specific gravity of soil grains
(d)max Maximum dry density
(d)min Minimum dry density
Properties of sands used
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Raining Technique--Calibration curves
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Schematic of Type A apparatus
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Type A apparatus
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Schematic of Type B apparatus
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Type B apparatus
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0
50
100
150
0 2 4 6
Shear movement, mm
Sh
ea
r s
tre
ss
, kP
a
Sand/Material 5
Sand/Material 4
Sand/Material 3
Sand/Material 2
Sand/Material 1
0
50
100
150
0 2 4 6
Shear movement, mm
Sh
ea
r s
tre
ss
, kP
a
Typical shear stress-movement curves
Type A Type B
Sand 6, ’n = 140 kPa
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0
20
40
60
80
0 1 2 3 4Shear movement, mm
Sh
ea
r st
ress
, kP
a
Type B (Plate below)
Type A (Plate above)
-0.8
-0.4
0
0.4
0.8
1.2
1.6
0 1 2 3 4
Shear movement, mm
Vo
lum
e c
ha
ng
e, %
Sand 4Material 5
n’ = 70 kPa
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Typical failure envelopes (Type B)
Peak Critical state
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(pB/) versus Relative density (Type B)
Thandavamurthy (1990)
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Variation of (pB/) with Dav (Type B)
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Proposed Roughness index
av
a
D
RR
Relative Roughness (R)
Ra Average RoughnessDav Average particle size
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Variation of (pB/) with R
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Variation of cvB with R
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Comparison of cvA with cvB
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Drained shear strength of fine-Drained shear strength of fine-grained soil-solid surface grained soil-solid surface
interfacesinterfaces
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Clays are sheet like and possess
plasticity characteristics
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Grain size distribution curves of the soils used
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PropertyProperty
SoilSoil
Red EarthRed Earth KaoliniteKaolinite IlliteIllite
Atterberg LimitsAtterberg Limits
Liquid limit (%)Liquid limit (%)
Plastic Limit (%)Plastic Limit (%)
Plasticity index (%)Plasticity index (%)
Grain SizeGrain Size
Sand (%)Sand (%)
Silt size (%)Silt size (%)
Clay size (%)Clay size (%)
Average particle size (Average particle size (m)m)
Coefficient of consolidation, CCoefficient of consolidation, Cvv (cm (cm22/sec)/sec)
3333
1919
1414
4444
4747
99
88.488.4
1.09 x 10 1.09 x 10 -3-3
5555
3333
2222
00
8080
2020
12.012.0
1.37 x 10 1.37 x 10 -2-2
131131
7878
5353
00
3636
6464
8.58.5
4.59 x 10 4.59 x 10 -4-4
Properties of cohesive soils used
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Variation of shear stress with deformation rate of illite
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Soil
Deformation rate (mm/min.)
Calculated Adopted
Red Earth
Kaolinite
Illite
0.05
0.63
0.02
0.05
0.25
0.05
Deformation rates calculated and adopted for tests under drained condition
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c’
nc
’
p’c
OC NC
Normal stress
She
ar s
tres
s
Failure envelope of a soil at constant preconsolidation pressure
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OCR=1
n’=100, 200 and 300 kPa
OCR=5
’p=500 kPa ’n = 100 kPa’p=1000 kPa ’n = 200 kPa’p=1500 kPa ’n = 300 kPa
OCR=10
’p= 500 kPa ’n = 50 kPa’p=1000 kPa ’n = 100 kPa’p=1500 kPa ’n = 150 kPa
FAILURE ENVELOPE WITH CONSTANT OCRRed earth
Illite
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2 4 6 80
Shear movement, mm Shear movement, mm
Typical shear stress-movement curves
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Typical failure envelopes
Normal stress
Normal stress
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Variation of ’B and (’B/’) with OCR
Bo
B/
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Variation of (B/) with Ra
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Variation of (B/) with R
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Comparison of values from Type A and Type B
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SUMMARYSUMMARY
Interfacial friction depends on mode of shear Interfacial friction depends on mode of shear for sands and the maximum value of friction for sands and the maximum value of friction angle is controlled by the type of apparatus angle is controlled by the type of apparatus used to evaluate the friction angleused to evaluate the friction angle
For clays, mode of shear has no influenceFor clays, mode of shear has no influence
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Research IssuesResearch Issues
Modeling of interface behaviour : shear Modeling of interface behaviour : shear stress-movement curvesstress-movement curves
RoughnessRoughness Hardness of solid materialHardness of solid material Rigidity of materialsRigidity of materials Mode of shearMode of shear Particle size and shapeParticle size and shape
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AcknowledgementsAcknowledgements
CSIR for funding
1.Prof. K. S. SUBBA RAO Department of Civil Engineering IISc, Bangalore
2. Prof. M. M. Allam Department of Civil Engineering IISc, Bangalore
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Thank you