Characteristics of seismic activity and tensile-slip features of fault under stress and displacement disturbance in full-mechanized workface

Full-mechanized mining method leads to large size gobs and serious stress and displacement disturbance on surrounding rock mass,which would cause a fault tensile-slip motion that induces high energy seismic tremors and fur-ther cause rockburst around the mining face. To solve this problem,based on the mining and geological background of 1303 full-mechanized workface in Zhaolou Mine,the tectonic and mining induced stress as well as their main control-ling elements were analyzed. The relationship between tensile-slip displacement along fault face and mining procedure was studied with analogue model,and the characteristics of seismic tremors were analyzed statistically. The results show that in the circumstance of mining the footwall coal seam of reverse fault,the tensile-slip motion of fault is determined by several key parameters,such as the ratio (k) of vertical force ( Pv ) and horizontal force ( Ph ) caused by mining activity,the dip angle of fault (θ) which represents the geometric features and the friction angle of fault (φ) which re-presents the mechanical features of fault. Additionally,the mechanical circumstance of the fault face should satisfy the stick-slip requirements as to cause seismicity. The stress and displacement disturbance induced by mining appear first in low overlaying strata of coal seam and then develop to high strata as the excavation processing,these would further cause the tensile-slip motion of fault. Seismic tremors mainly concentrate around the mining gob. With the increase of gob size,the daily frequency and energy of tremors around the mining face rise steadily,and the location of tremor fo-cus propagates to upper strata. The tensile-slip motion of Fd96 fault is the main cause for the tremors occurred in 1303 mining face,followed by the fracture and movement of overlay strata,and the tensile-slip motion of FZ14 fault has least influence on tremor activity.