Suction and time effects in rockfill deformation

Abstract

SummaryAmbient relative humidity controls the stress‐strain‐time behaviour of granular media exhibiting particle breakage. Breakage is the result of crack propagation inside loaded particles. The DEM model developed uses the results of subcritical crack propagation in brittle rock to predict breakage and the subsequent structural rearrangement. Two closed‐form solutions at grain level, stress distribution under diametrically opposed forces and the mode I crack propagation velocity, were included in the DEM formulation. Crack propagation velocity depends explicitly on relative humidity. The resulting model incorporates comminution and splitting modes of particle breakage as well as arbitrary grain shapes by means of aggregation of spherical microparticles. The model was first validated against a large diameter suction‐controlled oedometer test on hard limestone crushed gravel. Direct tests on contact properties (local stiffness and friction) helped to validate the model. The model was then used to predict the response of large diameter suction‐controlled triaxial tests on gravels having different (uniform) initial sizes. Time delayed deformations and wetting‐induced collapse deformations under maintained load are also a natural outcome of the model. They were shown to follow quite accurately the experimental results.