Study On Failure Law And Risk Of Water Inrush In Shortwall Block Mining In Suntuan Coal Mine

In the process of coal mining above confined aquifers,the development and expansion of the fractures in the shortwall block mining face is quite different from the traditional long-wall mining,which is due to the different mining methods for the floor of the stope.Disturbances are different and thus have a significant impact on the risk of water inrush during coal seam recovery.In this paper,the risk of water inrush in the failure law of shortwall block mining is studied.Firstly,the factors affecting the depth of damage and the risk of water inrush are analyzed stage by stage.Based on this,the shortwall block system is established,a system for influencing the risk of water inrush from the floor.At the same time,the mechanical theory of the semi-infinite plane body in the elastic wall is applied to establish the mechanical model of the shortwall blocktype floor rock.Based on the actual field data of Suntuan Coal Mine,UDEC numerical simulation software was used to simulate the development and expansion of cracks in the floor rock of the stope under different influencing factors,such as different lengths of sections,protective coal pillar width,mining height and mining methods.Finally,based on the drilling data of 10 coal in the 102 mining area of Suntuan Coal Mine,combined with the numerical simulation results,the shortwall block mining and the damage depth of the longwall mining floor are used to judge the risk of water inrush from different mining methods.Based on this,reasonable mining parameters were selected for the mining of 10 coal seams,which reduced the probability of water inrush from the floor during mining.The main achievements and understandings are:(1)The system of influencing factors of water inrush danger in shortwall block mining is constructed.The system mainly includes three aspects: the mining technology,the water-blocking performance of aquifuge and the water inrush intensity of aquifer,sum to 12 influence factor.(2)Establish the mechanical model of the shortwall block-type mining floor rock layer,combined with the semi-infinite plane body theory in elastic mechanics,superimpose the stress generated by the uniform load above the bottom plate on the bottom plate,and find any point O of the bottom plate.The stress state is finally judged by the Mohr-Coulomb yield criterion.(3)UDEC software was used to simulate the development and extension of the cracks in the floor rock under different block lengths,protective coal pillar width,mining height and mining method conditions.It is determined that the length of the block and the height of the block are directly proportional to the depth of expansion of the floor crack.The width of the protective coal column is inversely proportional to the depth of the crack expansion.It is also found that the development depth of the floor cracks under longwall mining conditions are bigger than that of the shortwall block mining.(4)Analysis of the water inrush risk of shortwall block mining and long-wall mining floor by the actual drilling data of 10 coal in the 102 mining area of Suntuan Coal Mine,combined with numerical simulation results and water inrush coefficient method.Compared the risk of water inrush in shortwall block mining with long wall mining.It is finally determined that when the long-wall mining method is adopted,the drilling water inrush coefficient of the 10 coal floor in the 102 mining area exceeds 0.1 MPa/m,accounting for 81%.According to the water inrush coefficient table,the part of the boreholes are located in the more dangerous and extremely dangerous water inrush level;when using the shortwall block mining method,the water inrush coefficient of the 10 coal floor in the 102 mining area is less than 0.1MPa/m,accounting for 86%,according to the water inrush coefficient table,the part of the borehole is at a safe and safe level,and the 102 mining area was engineered based on the predicted results.The paper has 30 pictures,5 tables,and 106 references.