非贯通节理岩体单轴压缩动态损伤本构模型

非贯通节理岩体是同时含有节理、裂隙等宏观缺陷及微裂隙、微孔洞等细观缺陷的复合损伤地质材料,基于此提出了在非贯通节理岩体动态损伤本构模型中应同时考虑宏、细观缺陷的观点。首先对基于细观动态断裂机理的经典动态损伤本构模型——TCK模型进行了阐述,其次针对目前节理岩体损伤变量定义中仅考虑节理几何参数而未考虑其强度参数的不足,基于能量原理和断裂力学理论推导得出了同时考虑节理几何及强度参数的宏观损伤变量(张量)的计算公式;第三,基于Lemaitre等效应变假设推导了综合考虑宏、细观缺陷的复合损伤变量(张量);第四,借鉴前人基于复合材料力学的观点,考虑了节理法向及切向刚度等变形参数对岩体动态力学特性的影响,进而建立了基于TCK模型的非贯通节理岩体单轴压缩动态损伤本构模型。并利用该模型讨论了载荷应变率、节理内摩擦角、节理厚度、节理法向及切向刚度和节理倾角等对岩体动态力学特性的影响规律。计算结果与目前的理论及试验研究结果比较吻合,从而说明了该模型的合理性。

A dynamic damage constitutive model for rock mass with non-persistent joints under uniaxial compression

The rock mass with non-persistent joints is a kind of compound damage geological material which contains both the macroscopic flaws such as the joint and crack and the mesoscopic ones such as the microcrack and microhole. Therefore, the viewpoint that the above two kinds of flaws should be simultaneously considered in the dynamic damage constitutive model for jointed rock mass is proposed. Firstly, the classic rock dynamic damage constitutive model, based on mesoscopic dynamic fracture mechanism namely TCK model, is discussed. Secondly, aiming at the shortcoming that the geometrical parameters are only considered but the strength ones are not in the current damage variable definition, the computational formula for the macroscopic damage variable (tensor) of the jointed rock mass which can consider the geometrical and strength parameters at the same time is obtained based on the energy principle and fracture mechanics theory. Thirdly, the compound damage variable (tensor) comprehensively considering macroscopic and mesoscopic flaws based on the Lemaitre equivalent strain hypothesis is deduced. Fourthly, based on the viewpoint of the compound material mechanics proposed by others, the effect of the joint deformation parameters such as the normal and shear stiffness on the dynamic mechanical behavior of rock mass is considered. Finally, the corresponding dynamic damage constitutive model for the jointed rock mass under uniaxial compression based on TCK model is established. The effects of the strain ratio of loads, internal friction angle of joints, joint depth, shear and normal stiffnesses of joints and dip angles of joints on the dynamic mechanical behavior of rock mass are discussed using the proposed model. The calculated results fit very well the current experimental and theoretical ones, indicating the rationality of the proposed model.