Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32586
An Experimental Investigation in Effect of Confining Stress and Matric Suction on the Mechanical Behavior of Sand with Different Fine Content

Authors: S. Asreazad


This paper presents the results that the soil volumetric strain and shear strength are closely related to the confining stress and initial matric suction under constant water content testing on the specimens of unsaturated sand with clay and silt fines contents. The silty sand specimens reached their peak strength after a very small axial strain followed by a post-peak softening towards an ultimate value. The post-peak drop in stress increased by an increment of the suction, while there is no peak strength for clayey sand specimens. The clayey sand shows compressibility and possesses ductile stress-strain behaviour. Shear strength increased nonlinearly with respect to matric suction for both soil types. When suction exceeds a certain range, the effect of suction on shear strength increment weakens gradually. Under the same confining stress, the dilatant tendencies in the silty sand increased under lower values of suction and decreased for higher suction values under the same confining stress. However, the amount of contraction increased with increasing initial suction for clayey sand specimens.

Keywords: Unsaturated soils, silty sand, clayey sand, triaxial test, constant water content.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 889


[1] E. E. Alonso, A. Gens, and A. Josa, “A constitutive model for partially saturated soils G ”,” Géotechnique, vol. 40, no. 3, pp. 405–430, 1990.
[2] S. J. Wheeler and V. Sivakumar, “An elasto-plastic critical state framework for unsaturated soil,” Géotechnique, vol. 45, no. 1, pp. 35–53, 1995.
[3] I. B. Bishop, A.W.T.; Donald, “Experimental study of partly saturated soil in the triaxial apparatus,” in Proceedings of the 5th International Conference on Soil Mechanics and Foundation Engineering, 1961, pp. 13–21.
[4] G. Bolzon, B. A. Schrefler, and O. C. Zienkiewicz, “Elastoplastic soil constitutive laws generalized to partially saturated states,” Géotechnique, vol. 46, no. 2, pp. 279–289, Jun. 1996.
[5] N. Khalili and B. Loret, “An elasto-plastic model for non-isothermal analysis of flow and deformation in unsaturated porous media: formulation,” Int. J. Solids Struct., 2001.
[6] B. Loret and N. Khalili, “An effective stress elastic – plastic model for unsaturated porous media,” Mech. Mater., vol. 34, pp. 97–116, 2002.
[7] D. G. Fredlund, N. R. Morgenstern, and R. A. Widger, “The shear strength of unsaturated soils,” Can. Geotech. J., vol. 15, no. 3, pp. 313–321, Aug. 1978.
[8] Q. Wang, D. E. Pufahl, and D. G. Fredlund, “A study of critical state on an unsaturated silty soil,” Can. Geotech. J., vol. 39, no. 1, pp. 213–218, 2002.
[9] C. W. W. Ng and A. C. F. Chiu, “Laboratory Study of Loose Saturated and Unsaturated Decomposed Granitic Soil,” J. Geotech. Geoenvironmental Eng., vol. 129, no. 6, pp. 550–559, Jun. 2003.
[10] H. Rahardjo, O. B. Heng, and L. E. Choon, “Shear strength of a compacted residual soil from consolidated drained and constant water content triaxial tests,” Can. Geotech. J., vol. 41, no. 3, pp. 421–436, Jun. 2004.
[11] C. Kayadelen, M. A. Tekinsoy, and T. Taşkıran, “Influence of matric suction on shear strength behavior of a residual clayey soil,” Environ. Geol., vol. 53, no. 4, pp. 891–901, Nov. 2007.
[12] G. E. Blight, “Strength and Consolidation Characteristics of Compacted Soils,” Imperial College London, 1961.
[13] B. S. Satija, “Shear behavior of partly saturated soils,” Indian Institute of Technology, Delhi, India, 1978.
[14] K. Chantawarangul, “Comparative study of different procedures to evaluate effective stress strength parameters for partially saturated soils,” Asian Institute of Technology, Bangkok, Thailand, 1983.
[15] N. A. Al-Shayea, “The combined effect of clay and moisture content on the behavior of remolded unsaturated soils,” Eng. Geol., vol. 62, no. 4, pp. 319–342, 2001.
[16] S. Jeong, J. Kim, and K. Lee, “Effect of clay content on well-graded sands due to infiltration,” Eng. Geol., vol. 102, no. 1–2, pp. 74–81, 2008.