Research on dynamic response characteristics of normal fault footwall working face and rock burst prevention technology under the influence of the gob area.

To study the effect of mining dynamic response characteristics on the footwall working face of the normal fault under the influence of the gob area, theoretical research, indoor experiment, and numerical simulation are adopted to analyze the stress manifestation characteristics, overburden movement, and energy evolution characteristics during the process of mining. The results show that: (1) In the process of mining toward the fault, the working face shows the change characteristics of "stable-activation mutation-final stability". At 20 m from the fault, the arch structure of the working face was damaged, fissures appeared near the high fault fracture zone, and the displacement of the overburden rock increased significantly; (2) the maximum value was reached at 4-8 m from the coal wall, and the superposition of tectonic stress and mining stress led to the concentration of the stress and energy accumulating on the top plate near the fault, and the data close to the gob area were even larger; (3) If the plastic damage zone of the high-level rock layer on the hanging wall and footwall of the fault appears to have a wide range of penetration, and the area formed between the shear displacement curve of the fault plane and the X-axis appears to have a significant enhancement, it is considered that the fault has been activated; (4) The size of the coal pillar of the fault is determined to be 40 m, and combined with the pressure unloading technique of the variable-diameter drilling hole, the validation is carried out through the micro-vibration monitoring, and the results of which can be used as a reference for the safety of the working face under similar conditions.

Study on the law of initial gas expansion energy and its feasibility in coal and gas outburst prediction.

In order to explore the relationship between IEERG and outburst intensity and verify the feasibility of the former in predicting coal and gas outburst, a series tests with different gases and different gas pressures were conducted on the basis of self-developed coal and gas outburst simulation system and IEERG measuring instrument. The results show that with the increase of gas pressure, the IEERG increases gradually. Under the same gas pressure, the coal has the strongest adsorption capacity for CO2, followed by CH4 and N2. When the IEERG is less than 24.40 mJ·g-1, no outburst will occur. When the IEERG is greater than 24.40 mJ·g-1, weak outburst will occur. When the IEERG is greater than 34.72 mJ·g-1, strong outburst will occur. This shows that the magnitude of IEERG is closely related to the outburst. The larger the IEERG, the greater the possibility of outburst and the greater the intensity of outburst. It is feasible to predict the risk of outburst using IEERG, and it can be quantified.