Study On Bag Filling Technology For Roof Of Extremely High Mining Roadway In Fully Mechanized Caving Face

Fully mechanized caving is the main coal mining technology in China's thick coal seams.It is very common to arrange the mining roadway along the roof,causing serious loss of the triangle coal at the end.Excavating the floor in front of the mining roadway can recover a large amount of triangular coal at the bottom of the head,but the mining roadway is extremely high,which results in poor stability of the surrounding rock of the roadway,and it is difficult to implement effective advanced support,which is very prone to major safety accidents.Therefore,it is of great significance to carry out research on the surrounding rock control technology of the ultra-high mining roadway in the fully mechanized caving face of thick coal seams for the safety of coal mine production and the recovery of resources.The paper takes Anyang Yong'an Hetuo Coal Mine as a test mine.In view of the current shortage of recovering triangular coal at the tip of the wooden pile filling roof,a bag filling control method for protecting roof and strengthening sides is proposed,and the feasibility of the technology is studied.According to the roof filling conditions and engineering requirements of the mining roadway,analyze and select the appropriate roof filling materials,analyze and select the appropriate filling timing and location,improve the filling system and formulate the use specifications,and design the filling process.Industrial tests were carried out on the 1112 working face of Hetuo Mine,and the filling bags were optimized and the filling process was improved according to the construction conditions.At the same time,the actual evaluation of the filling effect and economic benefits was made.Firstly,through the geological investigation of the ultra-high recovery tunnel engineering on the working surface and combined with theoretical analysis and numerical simulation,the stress distribution of the surrounding rock of the mining roadway in the inclined coal seam working face is obtained.The position where the surrounding rock of the roadway is liable to deform is determined and the supporting opinions are given.Secondly,According to the top plate filling conditions,the reasonable strength of the filling body should be greater than 1.4MPa,and the performance requirements of the bag filling material were analyzed,and the suitable water-ash ratio of the bag filling material was determined to be 3.5:1 through the test study.Then,using FLAC^3D numerical simulation to compare and analyze the stress distribution and deformation of surrounding rock before and after filling at the top of mining roadway.After filling,the vertical stress in the rock mass in the small area around the roadway is reduced,the amount of roof subsidence is reduced,the range of the plastic area is reduced,and the surrounding rock can be kept stable.After that,the timing and location of filling should be located 25-30m in front of the workface and the optimal design of the filling system and the formulation of the filling process were based on the material properties and the actual situation of the 1112 working face.The filling system has the advantages of smaller size,higher efficiency,automatic quantitative water addition,and mixing-pumping integration.Finally,the filling bag was optimized and the filling process was improved according to the construction conditions on site,which achieved efficient filling.The field test results show that the bag filling technology at the top of the ultra-high mining roadway can increase the working resistance of the monolithic column to more than 12MPa;Maximum deformation of 196mm after filling,which effectively suppresses the deformation of the roadway,and obtains good technical and economic benefits.A bag filling technology system at the top of a fully mechanized top coal mining face was born.