Experimental Study on the Response of Unsaturated Silt Due to Change in Drainage Conditions During the Triaxial Test Process

An experimental series is performed to study the response of unsaturated silt compacted on the dry and wet side of optimum water content due to change in drainage conditions during the triaxial test process. Soil samples were compacted at water content of 15% and 25% maintaining degree of compaction at 85%. The drainage conditions for pore air and pore water pressure was changed for isotropic consolidation, monotonic shear and water infiltration processes. The isotropic consolidation was performed by keeping pore air pressure drained and pore water pressure undrained. During monotonic shear both pore air and water pressures were undrained, whereas, the water infiltration was carried in fully drained conditions. The water infiltration was carried by keeping deviatoric stress and axial strain constant on the specimen. It was observed that the drainage conditions affect the deformation behavior of soil and results in a rapid decrease in specimen volume. Moreover, the stress paths for the specimens with constant deviatoric stress moved towards the failure line whereas the stress paths for the specimens with constant axial strain moved along the reference failure line.