Study On The Law Of Energy Zone Migration And The Mechanism Of Segmented Enlarged-diameter Borehole Destressing In High Static Stress Roadway

Rockburst is one of the typical dynamic disasters during coal mining operations.Increasing research on the prevention and treatment of rockburst disasters is an important task that must be sustained to ensure the sustained and rapid development of China's economy,social progress,and the safety of people's lives and property.The research on the mechanism of rock burst is the basis of prevention.In the course of its mechanism research,the research on the law of energy evolution of the roadway under high static load is not sufficient,and there are contradictions between pressure relief and support during its prevention.Therefore,this paper focuses on the energy evolution of strain-type impact laneway and the technology of large-diameter hole expansion and pressure relief,and uses a self-designed pressure chamber to carry out a five-sided single-face empty load test on red sandstone specimens.Furthermore,a numerical simulation was carried out on the indoor test,and the stress and damage evolution of the specimens obtained through the numerical simulation were summarized,and the law of energy evolution of the roadway under high static load conditions was summarized.The influence of different factors on the impact of deformed roadway is also studied.According to the evolution of impact energy of strain-type laneway,a method of reducing energy accumulation is proposed to prevent and control strain-type impact.Based on the analysis of the impact of the existing large-diameter borehole pressure relief technology on the support,a technical solution using subsection reaming pressure relief was proposed,and the relevant influencing factors of the subsection reaming pressure relief technology were analyzed and carried out.Field Test.The main conclusions of this article are as follows:(1)The self-designed pressure chamber can effectively meet the loading requirements of the red sandstone specimen under five-sided stress and one-sided empty surface.Through the indoor test,it is proved that there is energy accumulation inside the rock specimen before the strain-type impact occurs The energy release occurs when the free surface is destroyed.The coupling method of FLAC and PFC is used to simulate the deformation impact laboratory test to study the stress and damage evolution of the coal body during loading,and the energy evolution law of the coal body during loading is analyzed.(2)Numerical simulation method was used to analyze the influence of different roof elastic modulus,horizontal stress and pressure relief drilling diameter on the energy of roadway.It was pointed out that the increase of roof elastic modulus would increase the impact depth of roadway.The increase of horizontal stress will increase the damage of roadway,increase the accumulation of strain energy and release of kinetic energy.Increasing the diameter of the pressure relief borehole will reduce the model damage,weaken the model strain energy accumulation and kinetic energy release.(3)The FLAC strain softening model was used to analyze the influence of different diameters of conventional large-diameter boreholes on the pressure relief effect,roadway deformation and bolt support.The results show that increasing the borehole aperture can produce better pressure relief effect,but the excessive borehole aperture will lead to the increase of roadway deformation,the decrease of anchorage support strength and the influence of roadway stability.(4)The technique of reaming and pressure relief is to drill small diameter holes in the shallow section of the roadway side and large diameter holes in the deep section of the roadway side.Through numerical simulation,the influence of three key parameters of different section length ratio,shallow hole diameter and deep hole diameter on the anti-impact effect was analyzed.The results show that the diameter of the shallow hole does not affect the pressure relief effect,and the diameter of the deep hole plays a decisive role in the pressure relief effect.The optimal location of the hole reaming point is between the support depth of the roadway and the peak stress of the roadway.The diameter of the shallow hole should be considered as small as possible,while the diameter of the deep hole should be considered as large as possible.