Study On The Stress Distribution Law Of Coal Mining Under The "Five Containing" In Zhuxianzhuang Coal Mine And Its Influence On The Stability Of The Curtain Wall

In the north wing of Zhuxianzhuang Coal Mine,there is a thick layer of calcareous cementitious conglomerate fifth water-bearing rock formation,referred to as "five containing" for short.The karst is extremely developed,the water storage is large,and it is supplied by Ordovician water from the floor.The eight coal seams and eight mining areas in the north wing of the "five containing" lamination mine pose a great threat to the safety of coal.In order to realize the safe mining of the eighth coal seam,the mine built a curtain wall outside the outcrop of the coal seam to drain and intercept the "fivecontaining" layer.The purpose of this thesis is to safely mine the lower eighth coal seams under the "five containing" and protect the stability of the curtain wall.Through on-site investigations,laboratory tests,theoretical analysis,numerical simulation and field measurements.The distribution law of mining stress and its influence on the stability of curtain wall under "five containing" are studied.The main results of the thesis are as follows:(1)Based on the existence conditions of the coal seam overlying rock in the eighth mining area and the experimental results of the mechanical properties of the different layers of the curtain wall,the rock formations that affect the stability of the curtain wall were divided.The weathered crust-type rock formations located on the north line of the curtain wall,on the top of the "five containing" and the bottom of the "four containing",with broken rock mass and filled with yellow mud,are determined as the direct overburden of "four containing and five containing " as the main key influence area,the karst development area in the upper part of the "five containing" is identified as the secondary key influence area.(2)The curtain wall mechanics model is established,the boundary mechanics conditions of the curtain wall are determined,and the internal stress distribution characteristics of the curtain wall when it is not affected by mining are obtained through the semi-inverse solution method of elastic mechanics.(3)The UDEC Trigon model was established,and the study found that:(1)The plastic failure range of the rock formation in the "four containing and five containing" direct overburden zone is 140 m ahead of the coal wall in the section containing the bedrock,while in the "five containing" direct overburden coal seam section It is 160 m ahead of the coal wall;(2)The peak stress of the "five containing" karst zone in the "five containing" direct overlying coal seam is 14.1 MPa,and the range of influence is90.3m;the peak stress of the " five containing " direct overburden is 9.6 MPa,and the impact range is 84.7m.(4)Comprehensively consider the impact of mining stress on the internal stress,horizontal displacement,and plastic damage of the curtain wall boundary rock formation,and consider the safety factor of 1.5 to determine that the distance between the mining face and the curtain wall should be greater than 240 m.(5)The main factors that affect the stability of the curtain wall are determined,and the orthogonal test method and the analytic hierarchy process are used to analyze the sensitivity ranking and influence weight of each factor on the stability of the curtain wall,and it is concluded that the influence range of the supporting pressure is the influence The primary factor in the stability of the curtain wall.(6)Suggestions for measures to maintain the stability of the curtain wall are put forward.The research results provide a basis for the reasonable determination of the stop mining line of the working face and the stability of the curtain wall.This paper has 75 pictures,29 tables,and 114 references.