Volumetric behavior of saturated sands under poor drainage conditions

[ 1] Permeability variations have been identified as a key factor in controlling slope failure locations in rainfall-induced landslides. In this research, failure behavior in limited drainage conditions was investigated. Tests were performed on saturated sands by means of a modified triaxial system that could mimic the effect of low-permeability barriers present in the field. The tests were conducted by increasing the pore water pressure at different rates to study the effects of the speed of pore water pressure rise on soil failure. The results revealed a dependence of soil volume changes on the rate of pore water pressure increase. In general, the results showed that volume change of granular soils, which are under shear and confined laterally by low-permeability materials, depends on the initial porosity and the pore water pressure rate. These results are particularly valid during the early stages of soil deformation that precede wholesale slope failure.