北山花岗岩三轴循环加卸载声发射特性研究

Acoustic Emission Characteristics of Beishan Granite under Triaxial Cyclic Loading and Unloading

针对北山地下实验室场址深部花岗岩石开展三轴常规及循环加卸载力学特性研究试验,借助(PCI-2)AE监测系统对花岗岩在不同围压下的破坏全过程进行声发射实验,得到岩石破裂全过程中的力学参数,分析北山花岗岩循环加卸载效应、围压效应的耦合作用,并通过声发射振铃计数随加卸载循环次数、加载应力之间的发展关系对其破坏机理进行解释。北山花岗岩在三轴加卸载下,岩石弹性模量值随加卸载次数的增加呈下降趋势,而泊松比表现为增加趋势;在岩石的裂隙非稳定扩展时期,声发射能量累计数随时间变化曲线呈急速型增长,声发射事件数明显增多,可作为出现岩石破裂失稳的前兆信息。

Based on the triaxial test and cyclic loading-unloading test of granite in the deep part of the Beishan underground laboratory site,the acoustic emission(AE)test of the whole failure process of granite under different confining pressures was carried out with the aid of the PCI-2AE monitoring system.The coupling effect of cyclic loading and unloading effect and confining pressure effect of Beishan granite is analyzed,the failure mechanism was explained by the relationship between the number of acoustic emission ringing and the loading and unloading cycles and the loading stress.Under triaxial loading and unloading,the elastic modulus of Beishan granite decreases with the increase of loading and unloading times,while the Poisson ratio increases,the cumulative energy of AE increases rapidly with time,and the number of AE events increases obviously,which can be used as the precursor information of rock failure.