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为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(黏聚力与内摩擦角)的影响。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。
In order to study the influence of confining pressure on the mechanical properties of limestone and the failure mechanics model, the MTS815 was used to carry out triaxial compression tests on intact limestone samples. Based on the macroscopic failure mode of rock specimen, the model of tensile failure was established and the relation between peak strength and confining pressure was established. The relationship between shear strength parameters (cohesion and internal friction angle) )Impact. The results show that the elastic modulus, compressive strength and residual strength of rock samples increase with the increase of confining pressure, and the residual strength is nonlinearly correlated with confining pressure. When the rock samples finally rupture, the circumferential strain and axial strain The compressive strength of the rock is affected by the shear strength parameters and the tensile strength within a certain confining pressure range; the tensile shearing model determines that the rock shear strength parameter value increases with the crack angle Increase, compared with the pure shear model, the values are small. Therefore, when the confining pressure is low, it is of practical significance to consider the rock failure model.