复杂加卸载路径下闪长玢岩强度特征及声发射特性试验研究

Experimental study of the characteristics of strength and AE of Diorite porphyrite under complex loading and unloading path

选取典型深部矿山脆性岩石进行加卸载岩石力学试验,对复杂应力路径下脆性岩石的力学及破裂特征进行对比分析。采用声发射设备对破裂过程中声发射演化特征进行研究。研究表明,岩石的力学性质和变形特性与围压有密切的关系,围压的增加使围岩逐渐由脆性破坏向延性破坏过渡;对试件进行卸围压操作,容易造成岩石的突然破坏,同时造成了岩石强度的降低;由破裂形式素描图可知,卸载造成破坏更加剧烈,岩石表面出现大量竖向裂纹,卸载往往造成岩石的复合拉压破坏,且卸载破坏的的声发射计数率远远加载破坏。卸载破坏过程中,岩石声发射演化过程总体分为3个阶段,包括峰前平静期、活跃期及峰后平缓期,每个时期都有一个应力、应变及振铃计数临界值,需要通过大量试验及现场测试。

Loading and unloading rock mechanics tests were tested using brittle rock from a typical deep mine. Mechanics and fracture characteristics of brittle rock under complex stress path were analysed. The AE ring count evolution characteristic in rupture process was studies using acoustic emission equipment. Studies have shown that,mechanical properties and deformation characteristics of rock have a close relationship with the confining pressure and its failure mode gradually transited from brittle fracture to ductile failure. Unloading operation amounted to apply a reverse rally on specimen surface that usually caused the rapid growth of radial displacement which named expansion phenomenon. Damage degree of unloading was more severe than loading and a large number of vertical cracks appear on rock surface so that rock damage form was composite tensile and compressive damage and acoustic emission count rate when the rock damaging of unloading was far greater than loading. The rock internal AE ring count evolution process was divided into three phases in the unloading process including calm before the peak period,active period and gentle period after peak. There were critical value of stress,strain and AE ring count in every period that got by a large number of laboratory tests and field monitoring.