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

Abstract

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.

Discrete element simulation for investigating fragmentation mechanism of hard rock under ultrasonic vibration loading

“…With the rapid development of computer technology and advanced numerical techniques, computational simulations help us overcome this limitation and determine the characterization of crack initiation and growth in more detail 21‐27 . In recent years, the DEM has received considerable attention for its use in modeling the dynamic process of rock failure owing to its three advantages 28‐31 . Firstly, considering its micromechanical foundation, the DEM is a useful simulation tool for understanding the dynamic mechanism of rock materials at a microscale directly.…”

“…[21][22][23][24][25][26][27] In recent years, the DEM has received considerable attention for its use in modeling the dynamic process of rock failure owing to its three advantages. [28][29][30][31] Firstly, considering its micromechanical foundation, the DEM is a useful simulation tool for understanding the dynamic mechanism of rock materials at a microscale directly. Secondly, real-time contact searching makes the DEM convenient for observing the dynamic process.…”