围压作用下岩石峰后应力-应变关系模型

摘要

Any point in rock's post-peak softening stage satisfying Mohr-Coulomb critical failure criterion was assumed and then the post-peak rock subsequent yielding plane model was built. Several Mohr's stress circles were drawn using the rock state both at the peak position and the initial residual stage. Thenc andφ at the peak position or at the initial residual stage under different confining pressures were determined. The quadratic functional relationship betweenc orφand confining pressure was found. Regarding maximum principal strain ε as strain softening parameter,c and tanφ were the piecewise linear functions based on Mohr-Coulomb criterion and the friction angleφ was deduced. The model of post-peak stress-strain relationship was obtained finally. The strain softening processes under variable confining pressures for Tennessee marble in triaxial test were modeled using numerical cases and the results agree well with the test data. The results show that the model is reasonable and it can describe the post-peak mechanical behavior of the rock under different confining pressures preferably.%假定峰后软化阶段任意一点皆满足摩尔库仑极限破坏条件,建立岩石峰后后继屈服面模型.利用岩石峰值处和残余阶段初始处应力状态绘制几组莫尔应力圆,获得不同围压下峰值处和残余阶段初始处的黏聚力c和内摩擦角φ,然后分别建立黏聚力c和内摩擦角φ同围压的函数关系.基于莫尔-库仑准则,以最大主应变ε作为软化参数,以分段线性函数形式演化黏聚力c和内摩擦角φ的正切,反求内摩擦角φ,从而建立岩石峰后应力-应变关系模型.数值算例研究Tennessee大理岩三轴试验的峰后应变软化过程,模拟结果与试验结果较吻合.研究结果表明:建立的峰后应力-应变关系模型合理而可靠,可以较好地描述不同围压下岩石的峰后力学行为.