Study On Mining Pressure Rule Of 11215 Large Mining Face In Xiaojihan Coal Mine

With the development of coal mining technology,large mining and high mining has become an important coal mining method in many mining areas in China,especially in Jurassic coal field in northern shaanxi.However,the study of overburden rock structure and migration law in the process of large mining height working face is not thorough.During the stoping process of 11215 mining height working face in xiaojihan coal mine,it was found that some hydraulic support safety valve opened frequently.In order to better manage the working face,this paper carried out relevant research on the roof pressure law of 11215 mining height working face in xiaojihan coal mine.Xiaojihan coal mining no.2 coal seam,the average Angle of coal seam 2°,thick coal seam are 4.56 m,the side of 11213 working face,a side for planning 11217 entity coal working face,the face section width of coal pillar is between 20 m,11215 large mining height in the process of mining roof will support there are two kinds of boundary conditions,namely 3 edges clamped,one simply supported the front and both sides simply supported and clamped on both sides of back.This study takes the 11215 large mining height working face of xiaojihan coal mine as the engineering background.Firstly,based on the analysis of the structure of overlying strata on the working face,a reasonable mechanical model is established,its basic roof and key layers are analyzed,and the pressing step under the current working face cycle is calculated.Secondly,FLAC3D numerical simulation software was used to simulate the overburden movement breaking process and surrounding rock stress change of the front and back working faces respectively.The periodic breaking situation of the basic roof of the working faces under different boundary support conditions and the pressure step distance were obtained through calculation.At last,the in-situ observation of the working face's compressing strength,compressing step distance and working resistance of hydraulic support during the preceding and the latter two stages of stoping was made,and the law of the working face's ore pressure development under different boundary conditions was summarized and analyzed.The above research results show that:through the comparison of the law of ore pressure development in the front and back sections of the working face,it is known that the pressure level in the middle and lower sections of the working face increases and the pressure becomes more intense during the mining of the working face in the back section,so it is suggested to consider increasing the support strength of the hydraulic support in this area.This study not only has a guiding significance for the management of working face roof and safe and efficient stoping in this mine,but also can provide a reference for the mining of mines with similar geological conditions.