Analysis of rock mass stability according to power-law attenuation characteristics of acoustic emission and microseismic activities

Abstract

Under the influence of many factors, including complicated geological condition, high stress environment and strong disturbance by blasting, rock mass failure, and in some cases, dynamic failures would occur. Therefore, it is important to investigate and to understand rock mass stability during mining. In this study, Modified Omori Law (MOL) was applied to analyze the acoustic emission (AE) and microseismic (MS) sequence power-law attenuation characteristics in the laboratory and in situ. The MOL parameters, during the period of constant stress at lower stress level was much different with that at higher stress level, can reflect the stress level in rock. Before failure of the two rock specimens, the MOL is not applicable, indicating that the rock was close to the critical instability state. During the mining process, rock mass would be strongly disturbed by blasting. The AE sequence monitored from a ramp near the stope, and the MS sequence monitored from the whole rock mass near the stope all exhibited distinct power-law attenuation characteristics. The changes of MOL parameters, i.e., p, c and A, are very complex and related to many factors and it should cooperative analyze the three parameters to evaluate rock mass stability during the mining process.