Back analysis of rock burst risk and fault slip due to mining in the island panel along fault:A case study of island panel 3108 in Chaoyang Coal Mine

The relationship between complex geological structure,mining layout and rock burst is a major concern in coal mining. Especially when the island panel mining along the strike direction of fault,the stress state and overlying strata structure induced by the superposition of fault pillar and island panel will be more complex,pose a serious threat to the production and safety of rock burst coal mines. To study rock burst disaster induced by fault slip,the numerical algorithm of FLAC3D is developed by using Fish language,a systematic approach to numerically simulate an island longwall panel operation is proposed to investigate the dynamic response of fault slip instability. Based on the engineer- ing background of the island panel 3108 in Chaoyang coal mine,a numerical model of island panel mining with fault structure is constructed,the dynamic evolution characteristics of stress,displacement and velocity under mining dis- turbance are analyzed,the criterion of fault slip instability is determined,the relationship between fault slip instability and rock burst risk is summarized,and the result matches the field observations of strong tremor distribution. The re- sults show that as the mining panel is far from the fault,the fault slip does not occur. At this time,the dynamic load mainly comes from roof fracturing. When mining activities approach the fault,the calculation of the dynamic response of fault slip is performed over the area where the increase of relative shear displacement during dynamic analysis ex- ceeds 0. 05 m and where the shear stress along the fault decreases. Dynamic load induced by fault slip can be ex- pressed by seismic moment,energy and slip rate,etc. Dynamic load induced by fault slip can be expressed by seismic moment,energy and slip rate,etc. Numerical results show that when dynamic time is 0. 03 s,fault slip occurs,the seis- mic moment and the released energy reach a peak value. It is generally accepted that as the particle velocity reaches 0. 99 m / s,severe damage will be induced in the surrounding rock by fault slip. The slip rate increases and reaches a peak value at a dynamic time of about 0. 4 to 0. 5 s and subsequently decreases sharply. It is shown that during the ini- tial stage of the mining process,and in a square mining panel,fault slip is more likely to occur,leading to strong trem- ors and rock bursts,which become more notable in the later stages of the mining of the island panel.