裂隙花岗岩各向异性蠕变特性研究

 由于岩石的非均质性、裂隙的存在以及所处地质环境的复杂性，岩样在蠕变破坏过程中通常表现出各向异性的特点。为了描述岩石的这种各向异性蠕变性质，在经典弹黏塑性理论的基础上，提出黏塑性流动系数张量表达式，建立岩石各向异性弹黏塑性蠕变模型，将该模型嵌入到三维弹塑性细胞自动机模型中，开发岩石蠕变过程分析的三维弹黏塑性细胞自动机模拟系统(EPCA3D-EVP)，建立非均质岩石蠕变破坏过程的分析方法，该方法通过常规三轴数值试验来确定细观单元的强度和变形参数，通过蠕变试验确定其黏塑性流动系数，克服岩石力学模拟中“数据有限”的瓶颈问题，并通过对甘肃北山核废物地下处置候选场址的裂隙花岗岩三轴蠕变试验验证该模型和分析方法的正确性，合理地描述裂隙花岗岩在渗流–应力作用下产生各向异性的宏观现象。

STUDY OF ANISOTROPIC CREEP BEHAVIOR OF FRACTURED GRANITE

Due to the heterogeneity of rocks and the complex environment around rock mass，rock mass always presents anisotropic creep behavior in the loading process. In order to describe the anisotropic creep behavior of rocks，a viscoplastic fluidity parameter tensor is proposed；and the anisotropic visco-elastoplastic creep model of fractured rock is developed. The rock matrix and fracture are represented by introducing statistical distribution and weak element，respectively. A cellular automaton creep updating rule is established. This model is integrated into the EPCA3D and a numerical system EPCA3D-EVP to simulate the creep failure process of heterogeneous rocks is compiled in VC++ environment. The model and numerical method are validated against creep tests of fractured granite，which comes from the nuclear waste underground disposal candidate site in Beishan，Gansu province，China，with consideration of hydro-mechanical coupling effect. It is found that，larger lateral creep deformation of fractured granite under the effect of seepage，compared with the situation in dry condition. The EPCA3D-EVP system is used to simulate the creep test process. It is found that the simulated results are in well agreement with experiments，indicating that the developed model can well reflect the anisotropic creep phenomenon of fractured granite under the hydro-mechanical environment. The developed model can be used to long-term stability analysis of rock mass under complex conditions.