Interfacial friction between soils and solid surfaces

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Interfacial friction between soils and solid
surfaces
Dr. R. G. Robinson Assistant Professor Department
of Civil Engineering IIT Madras
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Typical field situations
Shallow foundation
Tip resistance
Deep foundation
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Typical field situations
Retaining walls
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Typical field situations
Reinforced earth walls
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Typical field situations
Geosynthetic reinforced earth slopes
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Typical field situations
Geotextiles
www.geosyntheticssociety.org
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Definition of coefficient of friction and
friction angle
P
P Normal Force T Shear Force Coefficient of
friction, mtandT/P where, d is the friction
angle
T
Soil
Solid material
P
Shear stress T/A
T
Normal stressP/A
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Apparatus used for evaluating friction angle
Potyondy (1961)
Rowe (1962)
Silberman (1961)
Ingold (1984)
Ingold (1984)
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Apparatus used for evaluating friction angle
Murthy et al. (1993)
Jewell and Wroth (1987)
Coyle and Sulaiman (1967)
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Apparatus used for evaluating friction angle
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Apparatus used for evaluating friction angle
Desai et al. (1985)
Uesugi and Kishida (1986)
Paikowsky et al. (1995)
Abderrahim and Tisot (1993)
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Some 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 (Dr)
emax 0.92
emin 0.35
(Lambe and Whitman, 1979)
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Particle shapes-- Sand
Coarse-grained soils
Subrounded
Rounded
Subangular
Angular
(Holtz and Kovacs, 1981)
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Maximum and minimum void ratio
ASTM D 4253 ASTM D 4254
Minimum void ratio
Maximum void ratio
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Direct shear test
tf shear strength of soil sn Normal
stress c cohesion intercept f angle of internal
friction
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Typical direct shear test results
Dense sand Loose sand
f
fcv
sn1
sn2
sn3
Displacement
Displacement
sn1
Angle of repose
sn2
sn3
Fcv Angle of repose
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Interface friction in sands
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Factors influencing interfacial friction angle of
Sand

• Surface Roughness
• Density of sand
• Normal stress
• Rate of deformation
• Size of apparatus
• Grain size and shape
• Type of apparatus

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Influence of sand density and surface Roughness
Toyoura sand
Soma sand
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Influence of sand density
Results of triaxial and soil-steel friction
tests (after Noorany, 1985)
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
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Influence of sand density
Acar et al. 1982
Levacher and Sieffert 1984
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Limiting values of d

• I Maximum Values
• Potyondy (1961), Panchanathan and Ramaswamy
  (1964), Uesugi and co-workers reported the
  limiting maximum value of d is the peak angle of
  internal friction fp
• Yoshimi and Kishida (1981) report that the
  maximum limiting value is the critical state
  friction angle fcv

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Minimum Values of ? Reported by Various Authors
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 7 tan -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
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Influence of normal stress
Potyondy (1961) Acar (1982) Both d and F
decreases with normal stress but the ratio
(d/f) remains constant Heerema (1979), Uesugi
and Kishida (1986), ORourke et al. (1990) d is
independent of normal stress For soft
materials d increases with normal stress due to
indentation of sand into the material
(Panchanathan and Ramaswamy, 1964 Valsangkar
and Holm (1997)
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Influence of Rate of deformation

• Heerema (1979)
• Rate of deformation from 0.7 to 600 mm/s
• No influence
• Lemos (1986)
• Rate of deformation 0.0038 to 133 mm/min
• No influence

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Influence of Size of apparatus

• Brumund and Leonards (1973)
• Rods with interface area of 225 cm2 and 400 cm2
• No appreciable difference
• Uesugi and kishida (1986)
• Simple shear apparatus, 40 cm2 and 400 cm2
• No influence
• ORourke et al (1990)
• Direct shear apparatus of size equal to 6cm x 6
  cm, 10 cm x10 cm, 28 cm x28 cm and 30.5x30.5 cm
• No significant influence

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Influence of grain size and shape
Rowe (1962)
Rowe (1962), Uesugi and Kishida (1986), Jardine
and Lahane (1994) d decreases with increase in
grain size
Friction angle (degrees)
Particle diameter (mm)
Angular particles give higher friction angle
(Uesugi and Kishida 1986 ORourke et al. 1990
Paikowski et al. 1995)
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Influence of type of apparatus

• Kishida and Uesugi (1987)
• Simple shear versus direct shear
• No difference
• Thandavamurthy (1990)
• Direct shear versus model pile tests
• Direct shear gives 20 higher
• Abderrahim and Tisot (1993)
• Direct shear- Ring torsion-Pressuremeter probe
• Direct shear gt Pressuremeter probe gtRing shear

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QUANTIFICATION OF INTERFACE ROUGHNESS
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d versus Roughness (Bosscher and Ortiz 1987)
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Normalized Roughness (Kishida and Uesugi 1987)
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Correlation with Normalized Roughness (Kishida
Uesugi 1987)
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Definition of modified roundness (Uesugi and
Kishida 1986)
Modified roundness of a particle
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Correlation between m, Rn and R
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Summary of some published interface friction tests
Author(s) Type of testing apparatus Results of investigation
Potyondy (1961) Direct shear apparatus with the sand on the top of test material d increases with density and dlimfp
Broms (1963) Direct shear mode by sliding the material over the sand A d value of 23o was obtained irrespective of sand density
Yoshimi and Kishida (1981) Ring shear with the test material on top of sand Density has no influence and dlimfcv
Acar et al. (1982) Similar to Potyondy d increases with density
Noorany (1985) Similar to Broms Influence of density is negligible
Uesugi et al. (1990) Simple shear with the sand on top of the test material d increases with density dlimfp
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Analysis of past studies

• From the review the following three conclusions
  can be drawn
• d increases with surface roughness and reaches a
  maximum limiting value
• For very rough surfaces, d tends to a limiting
  maximum value which could be either the peak
  angle of internal friction fp or the critical
  state friction angle fcv.
• d can either increase or remain constant with
  the increase in sand density.

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Summary of some published interface friction tests
Author(s) Type of testing apparatus Results of investigation
Potyondy (1961) Direct shear apparatus with the sand on the top of test material d increases with density and dlimfp
Broms (1963) Direct shear mode by sliding the material over the sand A d value of 23o was obtained irrespective of sand density
Yoshimi and Kishida (1981) Ring shear with the test material on top of sand Density has no influence and dlimfcv
Acar et al. (1982) Similar to Potyondy d increases with density
Noorany (1985) Similar to Broms Influence of density is negligible
Uesugi et al. (1990) Simple shear with the sand on top of the test material d increases with density dlimfp
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Schematic of Type A and Type B apparatus
Loading cap
SAND
SAND
Material
Type A apparatus
Type B apparatus
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Features of Type A and Type B apparatus
Sl.No. Features Type A Type B
I Apparatus configuration I Apparatus configuration I Apparatus configuration 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.
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.. 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 II Influence of type of apparatus on the results obtained II Influence of type of apparatus on the results obtained 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.
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Experiments in Direct shear apparatus
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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
Mild steel
Concrete surface
Concrete surface
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Grain size distribution curves of the sands used
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Properties of 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
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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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Typical shear stress-movement curves
Sand 6, sn 140 kPa
Type B
Type A
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Sand 4 Material 5 sn 70 kPa
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Typical failure envelopes (Type B)
Peak
Critical state
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(dpB/f) versus Relative density (Type B)
Thandavamurthy (1990)
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Variation of (dpB/f) with Dav (Type B)
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Proposed Roughness index
Relative Roughness (R)
Ra Average Roughness Dav Average particle
size
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Variation of (dpB/f) with R
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Variation of dcvB with R
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Comparison of dcvA with dcvB
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Drained shear strength of fine-grained soil-solid
surface interfaces
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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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Properties of cohesive soils used
Property Soil Soil Soil
Property Red Earth Kaolinite Illite
Atterberg Limits Liquid limit () Plastic Limit () Plasticity index () Grain Size Sand () Silt size () Clay size () Average particle size (?m) Coefficient of consolidation, Cv (cm2/sec) 33 19 14 44 47 9 88.4 1.09 x 10 -3 55 33 22 0 80 20 12.0 1.37 x 10 -2 131 78 53 0 36 64 8.5 4.59 x 10 -4
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Variation of shear stress with deformation rate
of illite
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Deformation rates calculated and adopted for
tests under drained condition
Soil Deformation rate (mm/min.) Deformation rate (mm/min.)
Soil Calculated Adopted
Red Earth Kaolinite Illite 0.05 0.63 0.02 0.05 0.25 0.05
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FAILURE ENVELOPE WITH CONSTANT OCR
Red earth
OCR1 sn100, 200 and 300 kPa OCR5 sp500
kPa sn 100 kPa sp1000 kPa sn 200
kPa sp1500 kPa sn 300 kPa OCR10 sp
500 kPa sn 50 kPa sp1000 kPa sn 100
kPa sp1500 kPa sn 150 kPa
Illite
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Typical shear stress-movement curves
Shear movement, mm
Shear movement, mm
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Typical failure envelopes
Normal stress
Normal stress
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Variation of DB and (DB/F) with OCR
DBo
DB/F
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Variation of (DB/F) with Ra
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Variation of (DB/F) with R
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Comparison of D values from Type A and Type B
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SUMMARY

• Interfacial friction depends on mode of shear for
  sands and the maximum value of friction angle is
  controlled by the type of apparatus used to
  evaluate the friction angle
• For clays, mode of shear has no influence

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Research Issues

• Modeling of interface behaviour shear
  stress-movement curves
• Roughness
• Hardness of solid material
• Rigidity of materials
• Mode of shear
• Particle size and shape

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Acknowledgements

• Prof. K. S. SUBBA RAO
• Department of Civil Engineering
• IISc, Bangalore
• 2. Prof. M. M. Allam
• Department of Civil Engineering
• IISc, Bangalore

CSIR for funding
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Thank you