Abstract

A hybrid finite–discrete element method is proposed to model the rock fracture behaviour under various loading rates. Three fracture models are proposed to predict the fracture initiation and propagation for modelling the transition from continuum to discontinuum. The modelling transition from continuum to discontinuum makes the hybrid method superior to the traditional continuum-based finite element method and discontinuum-based discrete element method. Moreover, the hybrid method considers the effect of the loading rate by implementing an empirical relationship between the static strengths and the dynamic strengths derived from the dynamic rock fracture experiments. Then, the Brazilian tensile strength tests are modelled to calibrate the proposed method under various loading rate, and demonstrate its ability in modelling the dynamic rock behaviours. The Notched Brazilian Disc tests are modelled to illustrate the capabilities of the proposed method in modelling different fracture modes. The hybrid finite element method has well modelled the stress propagation, fracture initiation and propagation, even the pure mode I, pure mode II and mixed-mode I–II fractures. It is concluded that the hybrid finite element method is superior to the continuum-based finite element method and discontinuum-based discrete element method in modelling the fracture behaviours of rock under various loading rates.

摘要

提出了一种混合有限离散元方法来模拟不同加载速率下的岩石断裂行为。提出了三种裂缝模型来预测裂缝的起始和扩展，以模拟从连续体到不连续体的过渡。从连续体到不连续体的建模过渡使得混合方法优于传统的基于连续体的有限元法和基于不连续体的离散元法。此外，混合方法通过实现静态强度和动态岩石断裂实验得出的动态强度之间的经验关系来考虑加载率的影响。然后，对巴西拉伸强度试验进行建模，以在各种加载速率下校准所提出的方法，并展示其在模拟动态岩石行为方面的能力。对缺口巴西盘试验进行建模，以说明所提出的方法在模拟不同断裂模式方面的能力。混合有限元方法很好地模拟了应力传播、断裂起始和扩展，甚至是纯模式 I、纯模式 II 和混合模式 I-II 裂缝。得出的结论是，混合有限元法在模拟岩石在不同加载速率下的断裂行为方面优于基于连续体的有限元法和基于间断体的离散元法。断裂的萌生和扩展，甚至是纯 I 型、纯 II 型和混合型 I-II 断裂。得出的结论是，混合有限元法在模拟岩石在不同加载速率下的断裂行为方面优于基于连续体的有限元法和基于间断体的离散元法。断裂的萌生和扩展，甚至是纯 I 型、纯 II 型和混合型 I-II 断裂。得出的结论是，混合有限元法在模拟岩石在不同加载速率下的断裂行为方面优于基于连续体的有限元法和基于间断体的离散元法。