Experimental and numerical investigations of undrained stress relaxation behavior considering freeze-thaw-drying-wetting effects for saturated clay

Abstract

The effects of freeze–thaw-drying-wetting cycles on undrained stress relaxation behavior are studied from the perspectives of physical experiments and numerical simulations using the proposed multi-set material point method (MPM) algorithm. The effectiveness of the established MPM model is validated by comparing the simulation results with experimental data. To gain insights into the microscopic characteristics of undrained stress relaxation, the evaluation focuses on the variations in elastic Green-Lagrangian strain, water pressure, water particle velocity, and solid particle space. The deviator stress relaxation and water pressure evolution are correlated with the decrease in elastic strain and spatial variation in water velocity, respectively. The stress relaxation process breaks the interparticle bonds and results in structural weakening. Freeze-thaw-drying-wetting cycles reduce the relaxed deviator stress within different relaxation stages and promote variation in water pressure, instability in water velocity field, and adjustment of solid particles.