Numerical simulation of deformation memory effect of rock materials in low‐stress condition using discrete element method

摘要

The slip behavior of the pre‐existing sliding planes (eg, cracks or inter‐grain boundaries) in rocks is a natural candidate for a mechanism of the deformation memory effect. Based on this mechanism, the deformation rate analysis (DRA) method can be used to measure in situ stress in low‐stress region. However, the traditional discrete element method (DEM) is unable to model the deformation memory effect of rock when the loading stress is lower than the crack initiation stress due to the insufficient consideration for sliding planes. The simulated stress‐strain curves obtained from previous DEM are linear in initial loading stage until cracks start to grow. In the present work, the properties of planes (ie, cohesion, frictional resistance, and relocking mechanism) are introduced into DEM contact model to simulate the deformation memory effect of rock in low‐stress region, and its feasibility was confirmed by comparing it with experimental results. It is found that there exists a suitable in situ stress range for DRA method when using it in low‐stress region, among which the inflection is precise. Four factors related to the sliding planes are discussed with parametric study to study their influence on the deformation memory effect. The results show that the cohesion and dip angle are highly related to the threshold value, while the friction coefficient and fraction of slide planes have little influence on the deformation memory effect in rocks.