含陡倾角软弱结构面的花岗岩力学特性及声发射特征

利用MTS 815.03岩石试验机对试件进行三轴压缩试验,采用DISP声发射测试系统进行声发射数据收集,并对含陡倾角软弱结构面的岩体试件和岩石试件进行试验对比.两种试件随围压的增加强度逐渐增加,破坏由脆性向延性转变;岩体试件总是沿结构面滑移破坏,岩石试件为剪切破坏.随着围压的增加,两种试件的弹性模量、变形模量、峰值应变和峰值强度增加;岩体试件弹性模量、变形模量值和峰值强度低于岩石试件,而峰值应变高于岩石试件.岩体试件内摩擦角小于岩石试件,而黏聚力大于岩石试件.随围压的增加,两种试件在峰值应力阶段声发射事件远高于其他阶段,而岩体试件声发射事件集聚量远远高于岩石试件.研究结果表明软弱结构面的存在降低了岩体的力学性质,因此在高放废物地质处置库选址时结构面发育特征是需要考虑的关键因素.

Mechanical features and acoustic emission characteristics of granite having a weak structure plane with steep dip angle

Triaxial compression testing was performed on an MTS 815.03 rock testing machine and acoustic emission data were collected by using a DISP acoustic emission test system. An experimental comparison was done between rock mass specimens having a weak structure plane with steep dip angle and rock specimens. The strength of the two kinds of specimens gradually increases with the increase of confining pressure, and the failure mode changes from brittle to ductile. Sliding failure along the structural plane occurs in the rock mass, while shear failure in the rock. With the increase of confining pressure, the elasticity modulus, deformation modulus, peak strain and peak strength of the two kinds of specimens increase. Moreover, the elasticity modulus, deformation modulus, and peak strength of the rock mass are lower than those of the rock, but the peak strain is higher. The internal friction angle of the rock mass is lower than that of the rock, but the cohesive force is higher. With the increase of confining pressure, acoustic emission events in the peak stress stage are far more than those in the other stages, and the acoustic emission events of the rock mass are more than those of the rock. The results of study show that the weak structure surface results in the lower mechanical properties of the rock mass, so it is a key factor in site selection for a high-level radioactive waste geological disposal repository.