Strength reduction model for jointed rock masses and peridynamics simulation of uniaxial compression testing

Abstract

The stability of surrounding rock is greatly affected by the mechanical properties of structural planes. At present, numerical methods have become an effective approach to scientifically evaluate the bearing capacity and predict the failure mode of jointed rock masses. Based on the basic theory of peridynamics, a strength reduction model is proposed to characterize the deformation and failure mechanisms of jointed rock masses. This model divides the bonds between material points into rock bonds and joint bonds and uses the strength reduction coefficient to establish the relationship between the two types of bonds. Therefore, the mechanical behaviour of rocks and joints can be described under a unified computational framework. Through the uniaxial compression simulation of intact rock, jointed rock mass with a single joint and jointed rock mass with multiple parallel joints and the comparison of the results with laboratory test results, the correctness and applicability of the model proposed in this paper are proven. The results show that during uniaxial compression, the damage first appears at the joints and then extends to the whole specimen, forming a penetrating fracture. The failure modes of jointed rock masses with different joint inclination angles are very different and correspond to three typical modes: sliding failure, splitting failure and mixing failure. Whether a rock mass with a single joint or a rock mass with multiple parallel joints is used, the peak load under uniaxial compression shows a typical V-shape with the increase in joint inclination angle. Although the failure modes of jointed rock masses with different joint inclination angles are similar under different strength reduction coefficients, their peak loads vary significantly. It is obvious that the peak load of jointed rock masses with different joint inclination angles decreases with the decrease in the strength reduction coefficient, especially in the uniaxial compression simulations of rock masses with multiple parallel joints. The research methods and results of this paper provide an important reference for future surrounding rock stability analysis in underground engineering and slope engineering.