岩石损伤破裂过程与声发射特性耦合规律实验研究

Experimental study on the rock damage and rupture process and coupling Law of AE features

采用MTS岩石力学试验系统和PAC公司SAMOS声发射监测系统,开展了灰岩、大理岩试样单轴受压破坏过程声发射特性试验,研究了岩石受力、变形过程中,声发射事件时间序列、空间分布、能量和b值等声发射参数特征,分析了岩样损伤破裂不同阶段与声发射参数的内在联系与特征规律.研究表明,岩石试件宏观破坏前,岩石中的裂纹处于非稳定扩展阶段,声发射事件急剧增加,达到弹性变形阶段的5～8倍,并逐渐向破裂面集中,弹性能加速释放,声发射累积能量急剧增加,为弹性变形阶段的103倍;声发射事件的振幅明显增加,可达弹性变形阶段的10倍;声发射波形峰值前的延续时间相对较短,频谱分散,出现多峰现象;通过对岩样的声发射源定位,有效采集到微损伤"积聚区",该区域的微损伤密度明显大于试样其它区域;随着岩样中微裂纹的局部扩展、贯通直至岩样破坏,b值和M值发生显著变化,岩样破坏前b值急剧减小,声发射事件震级明显增大.

MTS rock mechanics test system and PAC ＂s SAMOS acoustic emission monitoring system were adopted to carry out acoustic emission characteristics test on the damage process of limestone and marble samples under uniaxial compression, to study the acoustic emisson （AE） parameters, such as time series, spatial distribution, energy, and b - value in AE events during the process of under pressure and deformation, and to analyze the internal relations and laws between rock samples＇ damage and rupture in different stages with AE parameters. Results showed that before macroscopic damage of the rock samples, the cracks in rocks are at the unstable and expanding stage, when AE events increase rapidly, as much as 5 to 8 times in elastic deformation stage, and gradually concentrate on the rupture surface, the release of elastic energy accelerated, and the accumulative energy increase sharply, as much as 103 times in elastic deformation stage; the amplitude of AE events increase significantly, up to 10 times in the elastic deformation stage; before the waveform peak, AE wave have relatively short duration, dispersing spectrum, and occurrence of multi - peak phenomenon ; according to the AE sources positioning to the rock samples, centralize area of micro - damage, where the density of micro - damage is greater than other areas, is effectively collected; until the partial expansion and connection of the micro - cracks to the damage of the rock samples, b - value and M - value significantly change, and before the damage of rock samples, b - value decrease sharply and the magnitude of AE events increase significantly.