Intensity Weakening Theory For Rockburst Of Compound Coal-Rock And Its Application

Along with the mining scale and depth yearly increase, the catastrophe intensity and the harm induced by rockbursts are more obviously prominent. Simultaneously, it increases the possibility of the major disasters such as coal and gas outburst and gas explosion. So, weakening and controlling the appearance intensity of rockbursts is a key focus to prevent the coal-rock dynamic disasters in coal mines.The occurred vector of rockbursts is the compound coal-rock system composed by roof, coal seam and floor. On above, this thesis proposes the intensity weakening theory for rockburst of compound coal-rock. By weakening the strength of roof, coal materials and floor, and roof integrated thickness, the rockburst tendency and surplus energy of compound coal-rock system can be greatly declined, the dynamic balance between the energy dissipation and release can be maintained, the rockburst surplus energy accumulated in the coal-rock materials will be able to maintain a relatively low level, and the regional stress concentration gradient can be decreased, so the rockburst catastrophe intensity can be weakened.By the Disp-24 acoustic-electromagnetic (AE&EME) system in the experiments, the evolvement rules between the rockburst tendency indexes and roof strength and thickness, coal material strength of compound coal-rock was studied in thesis, the correlation between the rockburst tendency and the AE&EME signal characteristic parameters of compound coal-rock was established, espicially the omen AE&EME effect rules of rockburst failure. The results indicated the positive correlation between rockburst tendency and intensity of AE&EME signals, strength and thickness of roof, strength of the coal material.With TDS-6 microseismic (MS) experiment and monitoring research on spot, the correlation between rockburst tendency of the compound coal-rock material and roof thickness and MS intensity was studied, the evolvement rules of rockburst omen MS amplitude and frequency-spectrum was revealed. The results indicated the positive correlation between rockburst tendency of compound samples, roof thickness and MS intensity, and along with the rockburst tendency adding, MS signal presented the evolement rule of the increasing amplitude and the lower frequency-spectrum.By the Dynamic model function of FLAC2D numerical simulation software, the influential rules of different energy impact load, the strength and thickness of roof, the strength of coal material on the roadway rockburst effect was studied, the dynamic rockbust failure process of roadway was simulated. The results indicated that the higher the dynamic load impact energy (MS), the strength and thickness of roof and strength of coal material was, the stronger the roadway rockburst intensity was.On the basis of the theory about energy dissipation and release, the mechanical process and criterian from static deformation to dynamic rockburst was studied, the relation between rockburst surplus energy and rockburst tendency was revealed, the AE&EME effect mechanism of rockburst failure of compound coal-rock material was studied, the energy criterion of rockburst failure of compound coal-rock material was established, the main influential factors of compound coal-rock rockburst intensity was analyzed in detail.So, the model of the intensity weakening theory for rockburst of compound coal-rock was established, the key parameters and the effect testing system of intensity weakening of coal and rock materials was studied.By rockburst intensity weakening and controlling practice in 9202 higher danger working face of Sanhejian coal mine belong to Xuzhou Coal Mining Group (XCMG), the key factors affected rockburst intensity of working face were analyzed in detail,on above, the intensity weakening technology for rockburst of coal seam and roof strata deep hole relieve-shot was proposed, the synthetical testing system of intensity weakening effect was established, the safety production of working face was ensured ultimately.