Interfacial friction between soils and solid surfaces Dr. R. G. Robinson Assistant Professor Department of Civil Engineering IIT Madras.

Interfacial friction between soils and

solid surfaces

Dr. R. G. RobinsonAssistant Professor

Department of Civil EngineeringIIT Madras

Shallow foundation

Deep foundationTip resistance

Typical field situations

Retaining walls

Typical field situations

Reinforced earth walls

Typical field situations

Geosynthetic reinforced earth slopes

Typical field situations

Geotextiles

Typical field situations

www.geosyntheticssociety.org

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

Potyondy (1961) Rowe (1962) Silberman (1961)

Ingold (1984) Ingold (1984)

Apparatus used for evaluating friction angle

Jewell and Wroth (1987) Murthy et al. (1993)

Coyle and Sulaiman (1967)

Apparatus used for evaluating friction angle

Brumund and Leonards (1973) Ingold (1984)

Heerema (1979) Yoshimi and Kishida (1981)

Apparatus used for evaluating friction angle

Desai et al. (1985) Uesugi and Kishida (1986)

Paikowsky et al. (1995) Abderrahim and Tisot (1993)

Apparatus used for evaluating friction angle

Some TerminologiesSome Terminologies

Three Phases in Soils

S : Solid Soil particle

W: Liquid Water

A: Air Air

Void ratio, e = Vv/Vs Water content, w = Mw/Ms

Relative Density (DRelative Density (Drr))

Loosest Densest

100minmax

max

ee

eeDr

emax = 0.92 emin = 0.35

(Lambe and Whitman, 1979)

Particle shapes-- SandParticle shapes-- Sand

Rounded Subrounded

Subangular Angular

Coarse-grained soils

(Holtz and Kovacs, 1981)

ASTM D 4253; ASTM D 4254

Maximum and minimum void ratio

Maximum void ratioMinimum void ratio

Direct shear testDirect shear test

tannf c

f shear strength of soiln Normal stressc cohesion intercept angle of internal friction

n1 n2 n3Displacement

Displacement

Typical direct shear test results

n1

n2

n3

Angle of repose

cv

cv ~ Angle of repose

Dense sandLoose sand

Interface friction in sandsInterface friction in sands

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

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

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……

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

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

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

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)

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

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

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)

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

QUANTIFICATION OF INTERFACE ROUGHNESS

versus Roughness (Bosscher and Ortiz 1987)

Normalized Roughness (Kishida and Uesugi 1987)

50

50max )(

D

DLRRn

Correlation with Normalized Roughness (Kishida &Uesugi 1987)

2

31

1

42

2

1

l

rr

l

rrR

Modified roundness of a particle

Definition of modified roundness (Uesugi and Kishida 1986)

Correlation between , Rn and R

(0.27)

(0.19)

(0.17)

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

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.

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

Type A apparatus Type B apparatus

SAND SANDMaterial

Loading cap

Schematic of Type A and Type B apparatus

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

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

Experiments in Direct shear Experiments in Direct shear apparatusapparatus

Solid materials used

Material 1– Stainless steel

Material 2– Mild steel

Material 3– Mild steel

Material 4– Ferrocement

Material 5– Ferrocement

Surface profiles of the materials

Stainless steel

Mild steel

Concrete surface

Mild steel

Concrete surface

Grain size distribution curves of the sands used

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

Raining Technique--Calibration curves

Schematic of Type A apparatus

Type A apparatus

Schematic of Type B apparatus

Type B apparatus

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

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

Typical failure envelopes (Type B)

Peak Critical state

(pB/) versus Relative density (Type B)

Thandavamurthy (1990)

Variation of (pB/) with Dav (Type B)

Proposed Roughness index

av

a

D

RR

Relative Roughness (R)

Ra Average RoughnessDav Average particle size

Variation of (pB/) with R

Variation of cvB with R

Comparison of cvA with cvB

Drained shear strength of fine-Drained shear strength of fine-grained soil-solid surface grained soil-solid surface

interfacesinterfaces

Clays are sheet like and possess

plasticity characteristics

Grain size distribution curves of the soils used

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

Variation of shear stress with deformation rate of illite

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

c’

nc

’

p’c

OC NC

Normal stress

She

ar s

tres

s

Failure envelope of a soil at constant preconsolidation pressure

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

2 4 6 80

Shear movement, mm Shear movement, mm

Typical shear stress-movement curves

Typical failure envelopes

Normal stress

Normal stress

Variation of ’B and (’B/’) with OCR

Bo

B/

Variation of (B/) with Ra

Variation of (B/) with R

Comparison of values from Type A and Type B

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

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

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

Thank you