Unified elastoplastic framework for the volumetric behavior of unsaturated soils during drained, undrained, and static compaction tests

Abstract

When unsaturated soils are subjected to drained or undrained compression tests, they approach the saturated compression line with different slopes. During compression, four main phenomena occur in these materials: first, with the reduction in volume, the degree of saturation increases; second, with the reduction in the size of pores, the soil-water retention curve shifts on the axis of suction; third, these two phenomena produce an increase in the suction stress; and finally, this increase in suction stress produces a certain amount of collapse on the sample. In this paper, a unified elastoplastic framework is developed and coupled to a hydraulic model to simulate the volumetric behavior of unsaturated soils under different stress paths. This approach is based on a single equation with singled values for the compression and recompression indexes, resulting in a unified compression theory for soils. The comparison between experimental and numerical results shows the pertinence of the model.