深井中砂岩力学特性的声发射信号特征分析

ACOUSTIC EMISSION CHARACTERISTICS OF MECHANICAL PROPERTIES OF MEDIUM GRAINED SANDSTONE IN DEEP MINE

试验得到了深井中砂岩的基本力学性质参数,同时监测声发射信号,分析得到振铃计数率与应力释放(应变能释放)水平成正比,且当中砂岩主破断发生时达到最大值。按照中砂岩变形过程中的声发射信号特征,将破坏前的中砂岩形变过程划分为A、B、C三个阶段:A阶段形态上凸,峰值水平约300次/s,对应了岩石应力应变关系中的原生裂隙压密阶段;B阶段的声发射信号强度比较均匀,平均约100次/s,与应力应变关系中的弹性阶段相对应;C阶段开始时的声发射信号强度即高于B阶段,至主破断发生时台阶式升高,中砂岩破断前的振铃计数率达到最大值700次/s,该阶段主要对应于应力应变关系中的塑性变形阶段。结合应力应变曲线与声发射信号图,得到中砂岩的kaiser点,即该中砂岩在现场位置所承受的历史最大压力约为47 MPa,有利于指导深部地下工程设计。

By the basic mechanical properties test for medium grained sandstone in deep mine,its basic mechanical properties parameters was obtained. By the analysis of the AE signal,it was found that counting rate level varies directly with stress relief（ strain energy relief） level,which reaches the maximum with the happening of the main fracture of medium grained sandstone. According to the characteristic expression of medium grained sandstone AE signal,the signal before failure was divided into three phases,namely A,B and C. Phase A,shaped as a peak,has a peak value about 300 times per second,corresponding to primary fracture pressure consolidation stage in the rock stress-strain relationship. Phase B is relatively quiet,with a mean value about 100 times per second,mainly corresponding to elastic stage in the stress-strain relationship. Beginning from the appearance of high level AE signal to the happening of main fracture,the signal level in Phase C rises with time. The highest signal level before failure in Phase C can reach 700 times per second,mainly corresponding to plastic deformation stage in the stress-strain relationship. The position of kaiser point in the medium grained sandstone could be predicted and its corresponding stress value can be obtained from experimental data. Thus, the historical maximum pressure of rock（ 47 MPa）, where the medium grained sandstone sample was taken from,can be predicted.