不同应力路径下脆性岩石的加卸载响应比研究

加卸载响应比（LURR）理论是研究非线性力学系统稳定性的一种代表性方法。通过3种应力路径研究了冬瓜山典型脆性岩石包括砂岩、大理岩和蛇纹岩的LURR特征。以轴向应力为系统输入参数，单轴压缩轴向加卸载条件下，随着荷载增加，轴向应变的LURR值开始保持稳定，接近峰值时出现突增-回落现象，环向应变的LURR值在荷载中期出现反常突增情况。三轴压缩条件下保持围压恒定，轴向加卸载的轴向应变和环向应变的LURR值存在与单轴压缩类似的特征。研究了轴压不变围压加卸载的简单加卸载定义，轴向应变和环向应变的LURR值在逐级加卸载围压过程中保持稳定，然后在接近破坏时呈现较大幅度的增长。最后分析了不同应力路径下岩石的破坏特征。

Study on Load/Unload Response Ratio of Brittle Rocks under Different Stress Paths

Load/unload response ratio(LURR) theory is a representative method for studying stability of nonlinear system.Through three types of load/unload paths，LURR of three typical types of rocks are analyzed，including sandstone，marble and serpentinite sampled from Dongguashan copper mine.With the axial stress as input parameters，LURR of axial strain shows little change with load increase under uniaxial compression，whereas，presents sharp increase and drops when close to the peak.LURR of circumferential strain appears abnormal increase during the medium-term load.Under the three axial compression，the confining pressure keeps constant，and the LURR of axial strain and circumferential strain of axial load-unload is similar with that of the uniaxial compression.The definition of simple loading and unloading of confining pressure with constant axial compression is studied，and the LURR of axial strain and circumferential strain showed stable and then sharply increased when close to failure during the process of loading and unloading confining pressure step by step.Finally，the failure characteristics of rock under different stress paths were analyzed.