A dynamic damage constitutive model and crack propagation characteristics of heterogeneous rocks in uni-bond dual-parameter peridynamics

A dynamic damage constitutive model is proposed based on the uni-bond dual-parameter peridynamic (UDPD) model. The new model overcomes the shortcomings of fixed Poisson’s ratio embedded in the BBPD model, then takes into account the influence of a nonlocal PD force on calculation accuracy, and describes the nonlinear mechanical behavior and progressive failure of heterogeneous rocks under different strain rates. Based on the proposed dynamic damage constitutive model, three examples were simulated and compared with the experimental results. The effects of heterogeneity and strain rate on the crack propagation and failure mechanism of rocks were further studied. The results show that the proposed model improved the calculation accuracy and effectively simulated the mechanical behavior and crack propagation characteristics of heterogeneous rocks at different strain rates. The dynamic strength exponentially increased with shape parameters. Compared with homogeneous rocks, the inherent heterogeneity led to stress concentration, making the initial crack location more random, and the failure mode changed from double-cone conjugate shear failure to pulverizing failure. The increase in the strain rate altered the main crack’s propagation direction and increased the number of block failures on the outer surface of the specimen.