不同围压下灰岩力学特性及破坏力学模型研究

为了研究围压对灰岩力学特性及破坏力学模型的影响，采用MTS815对完整灰岩岩样进行三轴压缩试验。基于岩样宏观破坏形式，建立张拉剪切破坏模型，构建峰值强度与围压关系表达式；讨论张拉剪切模型与纯剪切模型对岩石剪切强度参数值（粘聚力与内摩擦角）的影响。研究结果表明：岩样弹性模量、抗压强度及残余强度均随围压升高而增大，且残余强度与围压呈非线性相关；当岩样最终破坏时，环向应变与轴向应变比值随围压升高呈负指数降低；一定围压范围内，岩石抗压强度受剪切强度参数和抗拉强度影响；张拉剪切模型确定岩石剪切强度参数值随破裂角增大而增大，与纯剪切模型相比，数值均较小。因此，低围压时，考虑岩石破坏模型具有一定的实际意义。

Study on Mechanical Characteristics Failure Mechanics Model on Limestone

To study the influence of confining pressure for mechanical properties and failure mechanics model on limestone, triaxial compression tests of intact limestone samples are carried out by MTS815.Based on the macroscopic failure forms, the tension and shear failure model is built and relative formula between the peak strength and confining pressure is established. Influence on the shear strength parameters (cohesion and internal friction angle) made by both of the tension and shear model and pure shear model is dicussed.The results show that elastic modulus, compressive strength and residual strength for samples increases with confining pressure increasing, and the relationship between residual strength and confining pressure is nonlinear. The ratio between hoop strain and axial strain reduces under negative exponent with confining pressure increasing when samples damaged final.Within the scope of a certain confining pressure, rock compressive strength are affected by shear strength parameters and tensile strength. The rock shear strength parameters determined by Tension and shear model increase with the rupture Angle increasing. Compared with the pure shear model, the value is smaller. Therefore, considering the rock failure model under low confining pressure has some practical significance.