ISSN: 1945-7545
CODEN: GTJODJ
Published Online: 25 July 2011
Page Count: 11

Strength and Small-Strain Stiffness Characteristics of Unsaturated Sand

Nyunt, T. T.
Nanyang Technological Univ.,

Leong, E. C.
Nanyang Technological Univ.,

Rahardjo, H.
Nanyang Technological Univ.,

(Received 15 November 2010; accepted 9 June 2011)

Abstract

Experiments were performed to investigate the effects of initial matric suction and net confining pressure on the small-strain stiffness and shear strength of reconstituted unsaturated sand. A series of constant water content tests was carried out using a modified triaxial apparatus equipped with local displacement transducers and bender elements. Reconstituted sand specimens were allowed to equalize at the required matric suction under net confining pressure using the axis- translation technique before shearing. After reaching matric suction equilibrium, shear wave velocities were measured prior to shearing. Multi-stage shearing tests were performed in order to investigate the effect of initial matric suction using the same specimen. The experimental results showed that at each net confining pressure, small-strain stiffness and peak shear strength showed a nonlinear relationship with matric suction with the change point near the air-entry value of the soil-water characteristic curve. Relationship between small-strain stiffness and net confining pressure was observed to be similar for saturated and unsaturated sands.

Keywords:
small-strain stiffness, shear strength, matric suction, triaxial test, multi-stage, unsaturated, sand

Paper ID: GTJ103589
DOI: 10.1520/GTJ103589
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