Failure characteristics and control technology of"L-shaped"isolated island working face in roadway inflection point area

CHENG Yanxue; WANG Hui; JIN Weihua; NIU Shuai

doi:10.13347/j.cnki.mkaq.20231271

Abstract：Pillar free mining technology is widely used in coal mining field in China.After the formation of isolated island working face,it is affected by strong mining movement,which leads to the phenomenon of large deformation and instability of mining road-way during coal mining,which becomes one of the difficult problems in roadway support at present.In order to solve the problems of serious deformation and crushing of surrounding rock at the inflection point of roadway with"L-shaped"working face and diffi-cult support,taking the inflection point of roadway with"L-shaped"island working face in Chengcun Mine as the engineering back-ground,the failure characteristics of inflection point of 14071"L-shaped"working face and the impact of different support strength conditions on plastic failure zone of return air roadway were investigated through comprehensive research methods such as theoretic-al analysis,numerical simulation and industrial experiment.The failure mechanism of"L-shaped"working face roadway inflection point area and the roadway control technology under stress concentration environment are studied.The results show that the concen-tration coefficient of abutment pressure in the inflection point area of the roadway increases,and the plastic damage range of the roadway side is large due to gangue extrusion,which leads to the fracture of the main structure of the ordinary support and the large deformation of the surrounding rock of the roadway can not be effectively suppressed.The developed integrated retaining board with retaining top and retaining bottom can control the deformation of the side of gob-side entry driving.The retaining board can reduce the deformation of surrounding rock by 50%,providing an effective way to control such surrounding rock.