Volume 24, Issue 1 (March 2001)
Mechanical Behavior of an Unsaturated Soil Under Multi-Axial Stress States
A series of drained (constant suction) true triaxial tests has been conducted on several identically prepared, 10-cm side, cubical specimens of recompacted silty sand to study the stress-strain-strength behavior of an unsaturated soil under multiaxial stress states and suction-controlled conditions. The experiments were conducted in a stress/suction-controlled true triaxial (cubical) setup following a multi-stage testing scheme. Matric suction states in the specimens were induced and maintained constant during testing by using the axis-translation technique. Imposed stress paths included an initial hydrostatic compression followed by conventional traxial compression, triaxial compression, or simple shear in the first octant of the octahedral stress plane. Test results are used to evaluate the nature of principal strain response of an unsaturated soil along multi-axial stress paths, and to observe the influence of matric suction on the shape, size, and position of the failure envelopes in the octahedral stress plane.