Engineering Geology

Engineering Geology

Shear Strength-Dilation Characteristics of Silty and Clayey Sands

Authors
Vahid Yousefpour 1
Amir Hamidi 2
Ali Ghanbari 2
1 Master of Science, School of Engineering, Kharazmi University
2 professor, School of Engineering, Kharazmi University
Abstract
Sandy soils usually contain different amounts of fines like silt and clay, causing some changes to their shear strength and dilation characteristics. Bolton [1] conducted some experiments on the different sands and suggested a relation between the parameters of the soil shear strength. In this paper, some experiments were performed on fine contained sand and the extended Bolton's relation was has been proposed. In this paper, shear strength and dilation behavior of a pure sand mixed with different amounts of silt or clay fines were studied using direct shear test device (100*100*30 mm), and a total of 96 tests were carried out. The samples were prepared separately using clay and silt contents of 0, 10, 20 and 30% in different relative densities of 70, 80, 90 and 100%. They were tested under three surcharge pressures of 90, 120 and 150 kPa, under particle crushing threshold. Variations in shear strength, maximum friction angle, critical state friction angle and cohesion, as well as dilation angle were investigated by increasing in the mentioned amounts. The results demonstrate that shear strength, dilation angle, maximum friction angle decreased by clay content increase, however, they increase with increase in silt content. In addition, a new form of the Bolton's relation for fine contained sandy soils was presented.
Keywords
Direct Shear Test
shear strength
dilation
clay content
silty sand
1. Bolton, M. D., "The strength and dilatancy of sands," Geotechnique, Vol. 36, No. 1 (1986).## 2. Poulos S. J., Castro G., France J. W., "Liquefaction Evaluation Procedure," J. Geotech. Eng., Vol. 111, No. 6 (1985) 772-792. ## 3. Haeri S. M., Hamidi A., "Steady state and liquefaction characteristics of gravely sands", Geotech. Geol. Eng., Vol. 23, No. 2 (2005) 141-156. ## 4. Bolton M. D., "Discussion: The strength and dilatancy of sands", Géotechnique, Vol. 37, No. 1 (1987) 219-226. ## 5. Simoni A., Houlsby G. T., "The direct shear strength and dilatancy of sand-gravel mixtures", Geotech, Geol. Eng., Vol. 24, No. 3 (2006) 523-549. ## 6. Hamidi A., Alizadeh M., Soleimani S. M., "Effect of particle crushing on shear strength and dilation characteristics of sand-gravel mixtures", Int. J. Civ. Eng., Vol. 7, No. 1 (2009) 61-71. ## 7. Hamidi A., Yazdanjou V., Salimi N., "Shear strength characteristics of sand-gravel mixtures", Int. J. Geotech. Eng., Vol. 3, No. 1 (2013) 29-38. ## 8. Hamidi A., Soleimani S. M., "Shear strength-dilation relation in cemented gravely sands", Int. J. Geotech. Eng., Vol. 6, No. 4 (2012) 415-425. ## 9. Hight D. W., Burland J. B., Georgiannou V. N., "The undrained behaviour of clayey sands in triaxial compression and extension", Géotechnique, Vol. 40, No. 3 (Jan. 1990) 431-449. ## 10. Pitman T. D., Robertson P. K., Sego D. C., "Influence of fines on the collapse of loose sands", Can. Geotech. J., Vol. 31, No. 5 (1994) 728-739. ## 11. Salgado R., Bandini P., Karim A., "Shear strength and stiffness of silty sand", Journal of Geotechnical and Geoenvironmental Engineering, 126 (5) (2000) 451-62. ## 12. Naeini S. A., Ziaie Moayed R., "Evaluatin of Undrained Shear Strength of Loose Silty Sands Using CPT", International Journal of Civil Engineering, Vol. 8, No. 2 (2008) 55-60. ## 13. Olmez M., "Shear strength Behavior of Sand- Clay Mixture", Middle East Technical University, Turkey (2008). ## 14. Gupta R., Trivedi A., "Effects of Non-Plastic Fines on the Behavior of Loose Sand: An Experimental Study", Elec. J. Geotech. Engrg., Vol. 14, No. B (2009) 1-15. ## 15. Chakraborty T., Salgado R., "Dilatancy and Shear Strength of Sand at Low", Jasce Ournal Geotech. Geoenvironmental Eng., Vol. 136, No. 1 (2010) 527-532. ## 16. Pakbaz M. S., Moqaddam A. S., "Effect of Sand Gradation on The Behavior of Sand-Clay Mixtures", Geotech. Cons. Mater., Vol. 3, No. 1, (2012) 325-331. ##17. Ojha S., Trivedi A., "Shear Strength Parameters for Silty- Sand Using Relative Compaction", Elec. J. Geotech. Engrg., Vol. 18, No. A (2013) 81-99. ## 18. Yu F., "Stress-dilatancy behavior of sand incorporating particle breakage", Acta Geotechnica Slovenica. 1, 14 (1) (2017) 55-61. ## 19. Patil U. D., Banerjee A., Hoyos L. R., Puppala A. J., Yu X., "Suction-induced dilatancy and stiffness in compacted silty sand via triaxial testing", In7th International conference on unsaturated soils (2018). ## 20. Amri S., Akchiche M., Bennabi A., Hamzaoui R., "Geotechnical and mineralogical properties of treated clayey soil with dune sand", Journal of African Earth Sciences. 1, 152 (2019) 140-50. ## 21. Yang S. L., Sandven R., Grande L., "Instability of sand-silt mixtures", Soil Dyn. Earthq. Eng., Vol. 26, No. 2–4 (2006) 183-190. ## 22. Poulos S. J., "The steady state of deformation", J. Geotech. Geoenvironmental Eng., Vol. 107, No. 5 (1981) 553-562. ##