Study on the dilatancy angle of rocks in the pre-failure domain

摘要

Based on experimental test results for a highly dilatant medium-grained sandstone, a bilinear model of the behavior of rock under compression has been developed to describe not only the compaction of rock material that occurs at low stress levels but also to account for the dilatant behavior that is specific to the stress range above the threshold of absolute dilatancy. The model uses two material parameters: Poisson's ratio and the dilatancy angle. The values of these parameters were determined based on both the relationship between volumetric strain and axial strain and the relationship between lateral strain and axial strain. In addition, a distinction was made in the paper between the dilatancy angle determined based on the total strain and the dilatancy angle determined based on the plastic strain components only. It has been shown that both these dilatancy angles characterizing the pre-failure dilatant behavior of the sandstone investigated are greater than those recommended to quantify the dilatant behavior of rocks in the post-failure domain in the literature to date.