不同加载速率下石灰岩与砂岩的声发射特征试验研究

Experimental Study on Acoustic Emission Characteristics of the Limestone and Sandstone under Different Loading Rate

通过RMT-150b岩石力学刚性伺服机进行了不同加载速率的单轴压缩声发射试验,测试和分析了变形破坏过程中石灰岩和砂岩的声发射特性。结果表明当加载速率增大时,强度为148.89~202.02 MPa的高强度石灰岩的单轴抗压极限强度和振铃计数极值均先增后减,而振铃计数频率先减后增;强度为77.52~94.59 MPa的低强度砂岩的单轴抗压极限强度随速率增大而减小,振铃计数极值先减后增,低速率时声发射活动在岩石损伤阶段活跃,振铃计数频率高且分布均匀,高速率时振铃计数易突增,振铃计数频率降低且分布不均。声发射能量则与振铃计数变化规律一致。研究结果对于利用声发射监测技术预测矿井围岩的失稳破坏具有一定意义。

The uniaxial loading acoustic emission test under different displacement loading rates was carried out by the RMT-150b rock mechanics rigid servo machine.The acoustic emission characteristics of limestone and sandstone during the process of deformation and destruction were tested and analyzed.The results show that when the loading rate increases,the uniaxial compressive ultimate strength and the ringing count of the limestones with the strength of 148.89~202.02 MPa will increase first and then decrease.The frequency of ringing count will decrease first and then increase.Then the uniaxial compressive ultimate strength of the sandstones with the strength of 77.52~94.59 MPa will decrease when the loading rate increase.At the same time,the extreme value of ringing count will firstly decrease and then increase.The acoustic emission activity is active in the rock damage stage when the loading rate is lower.In this case the frequency of the ringing count is higher and the distribution is uniform.After the rate increases,the ringing count is easier to increase sharply,and the frequency of ringing count is relatively smaller with uneven distribution characteristics.The change rule of acoustic emission energy is same with the rule of ringing count.The the above study results has a certain reference significance for predicting the instability and damage of mine surrounding rock by the acoustic emission monitoring technology.