The failure mode in rock engineering structures is closely related to the loading mode and loading rate, because of the inertial effects under a wide range of geological conditions. In this work, we propose a modified framework of the phase-field model coupled with plasticity, to investigate the effects of loading rates on the fracture mechanism in elastoplastic rock-like materials. By means of this framework, the damage-plasticity coupling effects on the mechanical responses and failure mode are also studied with an optimized pressure-sensitive plasticity model. The capability and accuracy of the proposed phase-field approach in capturing the nonlocal damage evolution is validated based on the elastic/inelastic homogeneous case with analytical solutions. Then the mixed-mode cracking behavior of the representative numerical examples are demonstrated under quasi-static and dynamic loading conditions from low to high loading rates. The failure modes, dynamic damage profiles and the crack propagation velocities in the examples with various loading rates were captured. Numerical results are discussed with comparison to previous experimental observations and available numerical works.

岩石工程结构的破坏模式与加载方式和加载速率密切相关，因为在广泛的地质条件下存在惯性效应。在这项工作中，我们提出了一种与塑性耦合的相场模型的改进框架，以研究加载速率对弹塑性类岩石材料断裂机制的影响。借助该框架，还使用优化的压敏塑性模型研究了损伤-塑性耦合对机械响应和失效模式的影响。基于具有解析解的弹性/非弹性均匀情况，验证了所提出的相场方法捕获非局部损伤演化的能力和准确性。然后，在从低加载率到高加载率的准静态和动态加载条件下，展示了代表性数值示例的混合模式开裂行为。捕获了具有不同加载速率的示例中的失效模式、动态损伤曲线和裂纹扩展速度。将数值结果与之前的实验观察和可用的数值作品进行比较进行讨论。