基于裂隙岩样的多组贯穿裂隙岩体峰后应力-应变曲线研究

在岩土工程中，裂隙岩体经常处于峰后变形状态，研究裂隙岩体的峰后应力-应变关系对预测结构的稳定性有重要意义。基于峰后软化阶段强度参数的逐渐演化行为，首先提出一个求岩石峰后应力-应变关系和裂隙峰后应力-切向位移关系的一般方法。然后采用摩尔-库仑强度准则，以岩石的最大主应变和裂隙的切向位移作为软化参数，假设强度参数为软化参数的分段线性函数，分岩体沿裂隙滑移破坏和沿岩石剪切破坏两种情况，提出多组贯穿裂隙岩体峰后应力-应变关系式的求法。最后，在算例中，分岩体沿裂隙滑移破坏和沿岩石剪切破坏两种情况给出了裂隙岩体的峰后应力-应变曲线，讨论了裂隙的平均间距、法向刚度和剪切刚度对峰后应变的影响。结果表明，裂隙的平均间距、法向刚度和剪切刚度越小，裂隙岩体的轴向应变越大。

Study of post-peak stress-strain curve of rock mass with multiple penetrative crack sets based on fractured rock samples

In geotechnical engineering, fractured rock mass is often in the post-peak deformational state. It is important for predicting stability of structure to study post-peak stress-strain relationship of fractured rock mass. Based on the evolution of post-peak strength parameters, firstly, a method for solving the relations of post-peak stress-strain of rock and stress-shear displacement of crack is proposed. Then using Mohr-Coulomb strength criterion, regarding maximum principal strain of rock and shear displacement of crack as softening parameters, assuming the strength parameter as a piecewise linear function of softening parameters, in the two cases that the rock mass fails along the fracture and through the rock, the method for solving relation of post-peak stress-strain of rock mass with multiple penetrative crack sets is presented. Finally, in case study, the post-peak stress-stain curves are given in the two cases that the rock mass fails along the fracture and through the rock; and the effects of mean space, normal stiffness and shear stiffness of cracks on post-peak strain are discussed. The results show that the smaller the mean space, normal stiffness and shear stiffness of cracks are, the larger the axial strain of fractured rock mass is.