Inducing mode analysis of rock burst in fault-affected zone with a hard-thick stratum occurrence

Study of movement characteristics of a hard-thick stratum (HTS) affected by a fault in a coalmine is significant to predict the dynamic hazards (i.e., rock bursts and shock bumps) because of the particular structural and mechanical properties of the HTS and the fault. Hence, using UDEC numerical simulation, the movement characteristic of HTS and fault-slipping law with different mining directions towards the fault were studied. Then, two different inducing modes and corresponding mechanisms of rock burst were obtained. The results show that the structure of overlying strata on two fault walls is different because of fault cutting and fault dip; it results in the HTS of two fault walls presenting different movement stage characteristics. From analysis of fault plane stress and fault slipping, we obtain that footwall mining has higher risk of rock burst than hanging wall mining. Finally, summarizing two different inducing modes of rock burst affected by the HTS and the fault: one that mainly resulted from the strain energy release caused by the HTS obvious bending and failure (i.e., hanging wall mining) and one that notably affected by fault slipping and HTS failure subsidence (i.e., footwall mining). A field case regarding microseismic monitoring is used to verify the numerical simulation results. Study results can serve as a reference for predicting of rock bursts and their classification into hazardous areas under similar conditions.