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Interfacial friction between soils and solid surfaces

Interfacial friction between soils and solid surfaces. Dr. R. G. Robinson Assistant Professor Department of Civil Engineering IIT Madras. Typical field situations. Shallow foundation. Tip resistance. Deep foundation. Typical field situations. Retaining walls. Typical field situations.

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Interfacial friction between soils and solid surfaces

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

  2. Typical field situations Shallow foundation Tip resistance Deep foundation

  3. Typical field situations Retaining walls

  4. Typical field situations Reinforced earth walls

  5. Typical field situations Geosynthetic reinforced earth slopes

  6. Typical field situations Geotextiles www.geosyntheticssociety.org

  7. Definition of coefficient of friction and friction angle P P Normal Force T Shear Force Coefficient of friction, m=tand=T/P where, d is the friction angle T Soil Solid material P Shear stress = T/A T Normal stress=P/A

  8. Apparatus used for evaluating friction angle Potyondy (1961) Rowe (1962) Silberman (1961) Ingold (1984) Ingold (1984)

  9. Apparatus used for evaluating friction angle Murthy et al. (1993) Jewell and Wroth (1987) Coyle and Sulaiman (1967)

  10. Apparatus used for evaluating friction angle Brumund and Leonards (1973) Ingold (1984) Heerema (1979) Yoshimi and Kishida (1981)

  11. Apparatus used for evaluating friction angle Desai et al. (1985) Uesugi and Kishida (1986) Paikowsky et al. (1995) Abderrahim and Tisot (1993)

  12. Some Terminologies

  13. Three Phases in Soils S : Solid Soil particle W: Liquid Water A: Air Air Void ratio, e = Vv/Vs Water content, w = Mw/Ms

  14. Loosest Densest Relative Density (Dr) emax = 0.92 emin = 0.35 (Lambe and Whitman, 1979)

  15. Particle shapes-- Sand Coarse-grained soils Subrounded Rounded Subangular Angular (Holtz and Kovacs, 1981)

  16. Maximum and minimum void ratio ASTM D 4253; ASTM D 4254 Minimum void ratio Maximum void ratio

  17. Direct shear test tf shear strength of soil sn Normal stress c cohesion intercept f angle of internal friction

  18. 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

  19. Interface friction in sands

  20. 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

  21. Influence of sand density and surface Roughness Toyoura sand Soma sand

  22. Influence of sand density…… Results of triaxial and soil-steel friction tests (after Noorany, 1985)

  23. Influence of sand density…… Acar et al. 1982 Levacher and Sieffert 1984

  24. 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

  25. Minimum Values of  Reported by Various Authors Notes:   Particle-to particle friction angle § Ri Modified roundness

  26. Influence of normal stress Potyondy (1961); Acar (1982): Both δ and Φ decreases with normal stress but the ratio (δ/f) remains constant Heerema (1979), Uesugi and Kishida (1986), O’Rourke 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)

  27. 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

  28. 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 • O’Rourke 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

  29. 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; O’Rourke et al. 1990; Paikowski et al. 1995)

  30. 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 > Pressuremeter probe >Ring shear

  31. QUANTIFICATION OF INTERFACE ROUGHNESS

  32. d versus Roughness (Bosscher and Ortiz 1987)

  33. Normalized Roughness (Kishida and Uesugi 1987)

  34. Correlation with Normalized Roughness (Kishida &Uesugi 1987)

  35. Definition of modified roundness (Uesugi and Kishida 1986) Modified roundness of a particle

  36. Correlation between m, Rn and R (0.27) (0.19) (0.17)

  37. Summary of some published interface friction tests

  38. 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 eitherincrease or remain constantwith the increase in sand density.

  39. Summary of some published interface friction tests

  40. Schematic of Type A and Type B apparatus Loading cap SAND SAND Material Type A apparatus Type B apparatus

  41. Features of Type A and Type B apparatus

  42. ….. Features of Type A and Type B apparatus

  43. Experiments in Direct shear apparatus

  44. Solid materials used Material 1– Stainless steel

  45. Material 2– Mild steel Material 3– Mild steel

  46. Material 4– Ferrocement Material 5– Ferrocement

  47. Surface profiles of the materials Stainless steel Mild steel Mild steel Concrete surface Concrete surface

  48. Grain size distribution curves of the sands used

  49. Properties of sands used Note: Gs Specific gravity of soil grains (d)max Maximum dry density (d)min Minimum dry density

  50. Raining Technique--Calibration curves

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