Numerical Study On Development Process Of Karst Collapse Column And Coal Pillar Reservation Under The Action Of Confined Water

With the development of the coal industry,more and more collapse columns are exposed.The existence of collapse columns will cause damage to the coal seam and surrounding strata,reduce the recoverable reserves,and affect the mining of working face.Based on the characteristics of its water conductivity,collapse columns will cause water inrush disaster to the mine.The water inrush problem of collapse columns has become one of the most serious disasters in the current coal mine,It has a negative impact on the safety of coal mining.The protection and treatment of water inrush from subsided column has been a hot topic for scholars.Under the influence of confined water,the research on how to leave coal pillars around the subsided column to ensure safe mining needs to be improved.From this point of view,this paper studies the development process of subsided pillar and the numerical simulation of coal pillar setting under the action of confined water.The plane,section and height of collapse column are studied;The formation mechanism from cave development to collapse column;Water flowing condition of collapse column;There are two water inrush mechanisms of bottom and side collapse columns;It provides a theoretical basis for the development process of collapse column and the study of coal pillar reservation.Taking No.12 collapse column in Fangezhuang of Kailuan as an example,the numerical simulation software is used to simulate the evolution.Through the setting of parameters,the characteristics of stress field,seepage field and plastic failure area in different stages of the development of collapse column are compared.It is concluded that the growth of collapse column is slow in the early stage of development,the stress cloud shape is small,and the influence on surrounding strata is small,The seepage field under the action of confined water is small and the plastic failure zone is small;In the strong development period,the stress cloud grows rapidly,the stress cloud pattern becomes larger than that in the early stage,the influence on the surrounding strata increases,the seepage field under the action of confined water increases,and the plastic failure area increases;During the decline period,the production is slow,the stress cloud pattern is larger than that in the strong development period,the influence on the surrounding rock is less than that in the strong development period,the flow field under the action of confined water is larger than that in the strong development period,and the plastic failure area is further increased;The results show that the stress cloud pattern and its influence on the surrounding strata are basically the same as those in the decline period,the seepage field under the action of confined water is basically the same as that in the decline period,and the plastic failure area is basically the same.Through the analysis of the stress field,the plastic failure area and the displacement of the top and bottom of the working face,it is concluded that the displacement of the top and bottom of the working face increases continuously in the process of the working face advancing.When the working face advances to 230 m and is 60 m away from the left wall of the collapse column,the plastic failure area between the working face and the collapse column is about to contact,and the stress value at the end of the working face increases slowly,Taking 230 m as the critical value of working face advancing,it is very likely to cause water inrush if the working face continues to advance,so coal pillar should be set here to ensure the safety of mining.Finally,the reliability of numerical simulation results is verified by engineering applicationThis paper has 51 pictures,6 tables and 67 references...