Study On The Mechanism And Evolution Law Of Stress Interruption During Roof Cutting By Rock Blasting

When the thick and hard key layer is covered on the stope,the influence range of the supporting surface of the working face will increase.If the reserved size of the coal pillar is insufficient,the roadway in front of the working face will be seriously deformed,and the maintenance cost of the roadway will be increased.The size of the coal pillars of the reserved roadway is increased,which is not conducive to improving the coal recovery rate.Therefore,it is of great engineering significance to study the preload stress relief control under the influence of key layers.To this end,this paper proposes the problem of controlling the dynamic pressure of the stope by using the rock burst blasting top pressure relief mining stress control technology,and using the theoretical analysis,numerical simulation and other research methods to systematically analyze the rock burst blasting top pressure relief machine.The evolution law of mining stress after pressure relief and the successful application of the research results to the 14200 working face engineering practice of Pingdingshan No.8 Mine,the main research results are as follows:(1)Based on the theory of rock mass blasting damage,the blasting pressure relief zone is divided,the damage mechanism of each zone rock damage is analyzed,and the damage radius of each zone is calculated.At the same time,based on the damage mechanism of each zone and the theory of fractal damage,weak face tie rod damage and micro-crack propagation damage,the mechanical model of damage degree of each zone is established,and the damage degree analytical formula of each zone is obtained,and LS-DYNA numerical software is used.The fitting analysis of the theoretical solution shows that the theoretical calculation and numerical analysis have a good fit.(2)By analyzing the distribution law and type of the stope stress,the main mining stress of the disturbed roadway is the static load generated by the coal seam and the dynamic load generated by the rock stratum breaking.For this reason,based on the theory of stress transfer and fault mechanics,the stress distribution model of the stope after debarge pressure relief is established,and the static load transfer mechanism of rock blasting is analyzed,and the transfer law of rock massdecompression and mining stress is revealed.At the same time,based on the stress wave transmission theory,the transmission attenuation mechanical model of dynamic multi-layer dielectric is established.The transmission attenuation mechanism of the dynamic load of the stope in the blasting pressure relief belt is analyzed,and the decay evolution law of the blasting pressure relief on the dynamic load of the stope is revealed.(3)Using the numerical simulation software to study the evolution law of mining pressure under the influence of different pressure relief level and different pressure relief heights,the results show that the pressure relief effect is more obvious when the pressure relief position is selected near the peak of the support stress,the leading support stress The smaller the influence range,the deformation of the roadway is reduced by nearly 2/3 compared with that before the pressure relief,but the peak value of the lead support stress after pressure relief increases.(4)Based on theoretical model,numerical simulation and analysis of engineering geological conditions,the pressure relief scheme for rock burst blasting is optimized,the blasting pressure relief area,parameters and process flow are designed and designed,and the mining stress is monitored in real time.The results show that Rock blasting pressure relief can effectively block the propagation of the supporting pressure of the working face,and reduce its influence range by nearly 1/3.It is of great significance to reduce the coal pillar size of the roadway and improve the mine recovery rate and dynamic pressure roadway deformation control.