循环载荷下深部花岗岩的破坏机理研究

The study of failing mechanism of deep granite under cyclic loading

在深部地下环境,随着温度升高和围压增大,花岗岩等硬岩呈现出从脆性到塑性转变的特性。同时,其力学行为和本构关系也会发生重大变化。岩石在循环载荷作用下,内部裂隙分阶段扩展,破坏过程受到裂隙空间分布、力学行为和加载条件等的影响。本文以水厂露天矿混合花岗岩为研究对象,通过三轴压缩试验和声发射监测试验,得到了岩石破裂各阶段的声发射特征值和相应的应力水平,获得了裂隙初始应力、裂隙贯通应力、峰值应力和残余应力的强度包络线,分析了深部花岗岩的破坏机理,确定了声发射信号和岩石破坏特征之间的对应关系,为工程应用提供了依据。

In deep underground environment,with the increasing of temperature and confining pressure,the characteristics of hard rock,such as granite,will transform from brittleness to plasticity.Also,its mechanical behaviors and constitutive relations have a great change.For the rock under cyclic loading,its inner cracks are extended by stages,and the failing process is affected by cracks spatial distributions,mechanics behaviors and loading situations.In this paper,the granite specimens were taken from the Shuichang open pit mine.The triaxial compression tests and acoustic emission(AE) monitoring tests were used to obtain the AE characteristics and their corresponding stress in each stage of failing process,so as the strength envelopes of crack initiation,crack damage strength,peak strength and residential strength.At last,the failing mechanism of rocks was analyzed and the relationship between AE characteristics and rock failing was described,which provided scientific basis for the engineering application.