Effect of wetting stress paths on mechanical behavior and instability of unsaturated soil in stress state space

Abstract

In current study, a test program is designed to observe the influence of wetting stress paths on behavior and instability of unsaturated soil in stress state space. The mechanical behavior was studied by performing three test series in constant matric suction plane. In first series, water infiltration was performed together with shearing starting from zero (0 kPa) deviatoric stress. In second series, first water was infiltrated at zero (0 kPa) deviatoric stress then samples were sheared in drained pore water pressure conditions. In third series, water was first infiltrated at zero deviatoric stress then specimens were sheared in undrained pore water pressure conditions. Instability was studied in constant shear stress plane by first shearing soil up to predefined level of deviatoric stress then infiltrating water keeping deviatoric stress constant on the specimen. This research also describes how unsaturated soil behavior and instability is varied with variation in net confining stresses when suction is decreased from initial measured value to start water infiltration with different wetting stress paths and their effect on shear state and failure surface in stress state space. The test results revealed that the movement of stress paths was independent of net confining stress, matric suction and shearing conditions employed in the study.

Keywords:

• Wetting stress paths
• mechanical behavior
• instability
• unsaturated soil
• water infiltration
• matric suction
• stress state space

Acknowledgments

Saitama University Japan and Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) is gratefully acknowledged for research facilities & financial assistance.

Disclosure statement

On behalf of all authors, the corresponding author states that there is no conflict of interest.