横观各向同性岩石弹塑性耦合变形的试验研究

EXPERIMENTAL STUDY OF ELASTOPLASTIC COUPLING DEFORMATION FOR TRANSVERSELY ISOTROPIC ROCKS

层理状岩石的变形具有各向异性和弹塑性耦合的特点。推导出各向异性岩石弹性变形参数是塑性应变和加载角度的函数。在此基础上,设计并完成具有明显层理状结构的泥质板岩的三轴循环加卸载试验。试验结果表明:泥质板岩的视弹性模量随塑性应变的增大呈指数规律衰减,视泊松比随塑性应变的增大而增大。提出2个经验函数来分别描述视弹性模量、视泊松比与岩样轴向塑性应变、加载角度间的关系,并获得经验函数中相关参数值,据此绘制视弹性模量随加载角度和塑性应变变化的三维空间曲面图。弹性变形参数的各向异性程度随塑性应变的增大而降低。

The bedded rocks have anisotropic and elastoplastic coupling mechanical properties. The elastic parameters of anisotropic rocks are the functions of plastic strain and loading angle. On this basis,triaxial cyclic loading and unloading tests of argillite with obviously bedded structures are designed and completed. The study results show that with the increase in plastic strain, the apparent elastic modulus decays exponentially,whereas the Poisson？s ratio increases. According to this phenomenon,two empirical functions are proposed to describe the relationships of apparent elastic modulus and apparent Poisson？s ratio vs. axial plastic strain and loading angle of rock specimens;and the values of related parameters are also obtained. The curved surface of apparent elastic modulus in the three-dimensional space changing with loading angle and plastic strain is drawn. The anisotropic degree of elastic modulus decreases with the development of plastic strain.