To describe the mechanical behavior of interfaces existing in rocks, a three-dimensional contact element model with a certain thickness was proposed that could simultaneously consider the heterogeneity, damage evolution and state variation of interfaces. The Weibull distribution function was employed to describe the rock heterogeneity. The damage evolution of the contact element was analyzed by using the equivalent damage method. Two criteria—the Mohr–Coulomb criterion and the maximum tensile stress criterion—were employed to assess the damage occurrence. Once the element was identified as being completely damaged, the state variation of the contact element was determined. Three types of element states—contact without sliding, contact with sliding, and separation—were taken into consideration. The model was then implemented and programmed into the finite element method and validated with experimental measurements and theoretical solutions for three classical rock mechanical problems, including one static problem (i.e., a direct shear test) and two dynamic problems (the seismic responses of rock joints and split-Hopkinson pressure bar tests), in an attempt to examine the applicability of the proposed contact element model. The results demonstrated that the contact element model can effectively model the rock interfacial problems and can therefore help solve problems in discontinuous rock masses.

中文翻译：

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基于三维损伤的接触单元模型模拟岩石界面行为及其验证与应用

为了描述岩石中存在的界面的力学行为，提出了具有一定厚度的三维接触单元模型，该模型可以同时考虑界面的非均质性，损伤演化和状态变化。用威布尔分布函数描述岩石的非均质性。使用等效损伤法分析了接触元件的损伤演化。两个标准-莫尔-库仑标准和最大拉伸应力标准-被用来评估损伤的发生。一旦确定元件完全损坏，就确定接触元件的状态变化。考虑了三种类型的元素状态-非滑动接触，滑动接触和分离。然后将该模型实施并编程为有限元方法，并通过实验测量和理论解决方案对三个经典岩石力学问题进行了验证，其中包括一个静态问题（即直接剪切试验）和两个动态问题（岩缝的地震响应）和分割霍普金森压力棒测试），以试图检验所提出的接触元件模型的适用性。结果表明，接触单元模型可以有效地对岩石界面问题进行建模，从而有助于解决不连续岩体中的问题。一次直接剪切试验）和两个动力学问题（岩石节理的地震响应和裂合霍普金森压力杆试验），以检验所提出的接触单元模型的适用性。结果表明，接触单元模型可以有效地对岩石界面问题进行建模，从而有助于解决不连续岩体中的问题。一次直接剪切试验）和两个动力学问题（岩石节理的地震反应和裂合霍普金森压力杆试验），以检验所提出的接触单元模型的适用性。结果表明，接触单元模型可以有效地对岩石界面问题进行建模，从而有助于解决不连续岩体中的问题。