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Taking No.1310 working face of Xiaoyun Coal Mine as the engineering background, the initial breakage and instability position of the suspension roof was determined by calculation, the large amount of bending strain energy released was analyzed when the hard roof is broken, and FLAC3D numerical simulation was used to analyze the mining stress changing during the initial mining of the deep overhand mining isolated island working face. Based on the energy released by the breakage of the suspension roof and the stress concentration coefficient during initial mining exceeding the critical value of rock burst, it was judged that the rock burst was likely to occur during the initial mining of the deep isolated island working face. By taking comprehensive pressure relief measures such as large-diameter borehole pressure relief combined with roof deep hole presplit blasting and other comprehensive pressure relief measures, the impact risk in the initial mining stage was prevented and controlled. The results show that the weakened zone formed by the pressure relief drilling destroys the bearing structure of the coal body, which obviously reduces the stress of the shallow coal body near the roadway, and the stress peak shifts to the deep part of the coal body. Blasting damages the roof, releasing or transferring the elastic energy accumulated in the hard roof in advance, so as to reduce the possibility of rock burst in the initial mining stage of isolated island working face.

To solve the problems such as the poor effect of water control technology for “high limit mining” and the serious water disaster of the aquifer of Luohe Formation in the panel mining of the second stage in a coal mine, combined with the fine exploration data of aquifer, the mode of “progressive seepage” water filling in the large thick semi-permeable aquifer of the roof is proposed, which is demonstrated by the mathematical model establishment, numerical simulation and field measurement. The field tests show that when the roof fracture zone spreads to the aquifer of Luohe Formation, based on the previous analytical method under the condition of overall drainage of aquifer, it is predicted that the water inflow of working face can reach nearly 4 000 m3/h. However, under the guidance of “progressive seepage” water filling mode, the water inflow of working face No.304 and No.206 during stoping is respectively 302 m3/h and 200 m3/h. The results fully verify that the drainage method of the coal mine is different from the traditional “progressive” water level drainage mod.

In-situ stress is the basis for designing mine roadway supports. Firstly, based on the GA-BP algorithm, establish a numerical analysis model, apply orthogonal tests, to establish the relationships between in-situ stress and lateral pressure coefficient, different rock parameters. Then, the optimization model is built by setting the sum of squares difference between measured and calculated in-situ stresses as optimization targets. Finally, using the model to solve the in-situ stress. Results show that the relative error between GABP algorithm inversion results and measured values is 2.9% averagely, while the relative error between BP algorithm inversion results and measured values is 4.4% averagely. Inversion methods can provide reference for similar mine in-situ stress inversion.

Based on the blockage of the rescue route of roadway caused by the collapsed accumulation body in coal mine underground fault fracture zone, the geological characteristics and accumulation form of fault fracture zone are analyzed. According to the theory of natural balance arch and elastoplastic theory, the height, the width of the accumulation body roof-fall area, the range of the accumulation body, and the height calculation formula of the accumulation body were derived. At the same time, the mechanical analysis of the accumulation body was carried out, and the calculation formula of the boundary force of the accumulation body was deduced, and the experimental verification was carried out by using the self-made experimental device. The results show that the collapse in the roadway of the fault fracture zone is mainly filled with rock fragments. The "self-organization" adjustment mode is divided into lateral movement adjustment, longitudinal movement adjustment and self-rotation adjustment; the maximum lateral instability width of the accumulation body, the longitudinal maximum collapse height of the accumulation body are related to the roadway height, roadway width, lateral stress coefficient, and the internal friction angle of the fragment filling body; the accumulation range is the total of the length of the fault fracture zone, the pre-decomposition zone, and the post-decomposition zone. The passive resistance is related to the bulk density of the block, the buried depth, the horizontal distance of the highest point of the accumulation body, and the natural repose angle; the correctness of the passive resistance calculation formula is verified by the experiment, but the formula has certain applicable conditions, depending on the ratio K of the particle size to the horizontal size of the accumulation body, the smaller the K value, the more suitable the formula is. The study provides theoretical and technical support for the implementation of the pre-repair roadway collapse form, rescue time, and the development of corresponding rescue programs. [ABSTRACT FROM AUTHOR]