为了研究花岗岩脆性和延性破坏过程的声发射特性和损伤演化机制,通过花岗岩单轴试验和颗粒流程序进行了不同围压试验,获得了花岗岩破坏过程中的声发射曲线并再现了内部损伤演化过程。试验结果表明:花岗岩脆延破坏分界围压约为100 MPa;花岗岩脆性破坏时最大声发射强度的滞后效应受围压影响显著,围压越大滞后效应越不明显,延性破坏时最大声发射强度与峰值应力同时出现,滞后效应消失。花岗岩脆性破坏声发射曲线为单峰型,延性破坏声发射为平缓曲线。脆性破坏花岗岩内部严重损伤区少且分布集中,损伤区裂隙发展方向单一,延性破坏内部损伤区多且遍布整个试样,损伤区裂隙主要沿2个相互正交方向发展;花岗岩破裂角随围压增大逐渐减小,由低围压下的破裂面转变为高围压下的破碎带,低围压脆性破坏花岗岩被破裂面切割成数块,高围压下延性破坏呈粉碎性状态。

In order to explore the acoustic emission characteristics and damage evolution mechanism of granite in brittle and ductile failure processes, we carry out uniaxial experiment on granite, and simulated experiment under different confining pressures through PFC(particle flow code). On the basis of test, we obtain the acoustic emission curve in failure process and reproduce the evolution process of internal damage. Test results are as follows: 1) critical confining pressure from brittle failure to ductile failure is 100MPa; 2) lag effect of maximum acoustic emission intensity is significantly affected by confining pressure in brittle failure, and the greater confining pressure is, the less obvious lag effect is; 3) in ductile failure, maximum acoustic emission intensity and peak stress appear in the same time without lag effect; 4)acoustic emission curve has single peak in brittle failure ,while gentle curve form in ductile failure; 5)there are few internal serious damage zones in brittle failure with concentrated distribution, and crack extension tends to be in the same direction; 6) internal serious damage zones which distribute throughout the specimen in ductile failure are more than those in brittle failure, and crack extends mainly along two mutually orthogonal directions ;7) rupture angle gradually reduces as confining pressure increases, and rupture surface transforms into crushing zone with the increasing of confining pressure; 8) in brittle failure with low confining pressure, rock is cut into a few blocks ,while in ductile failure with high confining pressure, the rock destruction is comminuted.