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利用TYP-500型三轴试验机进行三轴常规及循环加卸载试验,借助PCI-2声发射系统记录花岗岩破坏过程的声发射信号。试验结果表明:循环加卸载试验使花岗岩的弹性模量变大,较常规三轴压缩强度,循环加卸载强度大致提高了3.5%;随着循环加卸载次数的上升,花岗岩不可恢复的变形量变大,为最大变形的5%左右,表明花岗岩具备明显的“记忆性”功能;花岗岩声发射振铃计数突变点大致在峰值应力的90%处,可将此作为判断花岗岩破坏的前兆;围压越大,弹性能所占比越大,说明围压影响岩石内部能量的分配;在峰值强度的0.3~0.4处,弹性能所占比达到0.9左右,说明在荷载达到试件峰值强度之前,岩样内部的能量演化已经发生转变,并保持在一定水平。
Three-axis conventional and cyclic loading and unloading tests were carried out on a TYP-500 triaxial testing machine. Acoustic emission signals of the granite failure process were recorded by the PCI-2 acoustic emission system. The experimental results show that the cyclic loading and unloading tests increase the elastic modulus of granite, which is 3.5% higher than that of conventional triaxial compressive strength and cyclic loading and unloading. As the loading and unloading cycles increase, the unrecoverable deformation of granite becomes larger , Which is about 5% of the maximum deformation, indicating that the granite has a clear “memory” function. The granite rockengencounting abrupt change point is about 90% of the peak stress, which can be used as a precursor to judge the granite damage. The larger the pressure, the larger the elastic energy, indicating that the confining pressure affects the energy distribution inside the rock. At the peak strength of 0.3-0.4, the proportion of elastic energy reaches about 0.9, indicating that before the load reaches the peak strength of the specimen, The evolution of energy within rock samples has changed and remains at a certain level.