Study On Gob-side Entry Retention Technology Of "Combined" Filling Body At Roadway Side Of Fully Mechanized Caving Face With High Gas

In recent years,due to the modernization of coal production,the shortage of mining replacement and the waste of coal resources are becoming more and more serious,so the gob-side entry without pillar mining technology has gradually become the key technology of coal resources mining.Lu An mining area according to its geological conditions,after a long period of exploration and practice,in the gas mines along the generally used for "soft" mold + concrete filling body lane,however,as the scale of mining and mining depth increasing,the left lane along gob area gradually presents the characteristics of gas emission and sharp deformation of surrounding rock,"soft" mold + concrete lane beside the filling body cannot achieve the stability of the surrounding rock control and the goaf seal in time,to the stability control of surrounding rock of roadway and gas concentration management has brought new challenges.Taking Lu’an group get a village coal mine 2603 working face as the engineering background,the traditional gas along the empty left lane of full-mechanized caving mining face caused by the filling body meet top on lax and spontaneous combustion of coal seam gas leakage,to control the instability of roadway surrounding rock and the implementation of goaf seal as the main starting point,this paper studies the filling body and the interaction mechanism of surrounding rock,for the "combination" filling body stability of roadway surrounding rock and the influence of the active support within the lane technology parameters optimization,put forward the concrete pouring as "support" and the high water material filling as a "top" of the "combination" of the filling body of surrounding rock control technology,The original roadway support parameters were optimized to effectively control the stability of roadway surrounding rock and reduce the concentration of gas in the working face.The main achievements of this paper are as follows:(1)Based on the theory of masonry beam,and the limit equilibrium theory,in combination with the practical geological conditions of get a village coal mine 2603 face,analyzes the basic roof caving mining face along the empty left fracture morphology and the interaction mechanism of roadway surrounding rock and filling body,calculate the geometry parameters of the key block and abutment stress influence range,in view of the filling body and the role of the roadway surrounding rock relationship "combination" filling body surrounding rock control technology is presented.According to Winkler’s elastic foundation hypothesis,the basic physical and mechanical model of gob-side entry retention and the "compression-support" equilibrium structure model were established.Combined with the basic roof fracture morphological parameters,the supporting resistance and layered height of the "composite" filling body were calculated,and the strength and basic dimensional parameters of the "composite" filling body’s top layer were preliminarily determined.(2)Through the analysis of the material properties and mechanical properties of concrete and high water materials,the construction materials of the support layer and the top layer of the "combined body" specimens and the matching scheme are determined.The mechanical properties of the "combined body" were measured by CMT universal testing machine,and the parameters were determined.Combination with the engineering practice,considering the broken roof of "combination" in the process of filling body are the effects of transverse shear stress,through the theory to calculate the cutting head resistance on the filling body caused by the transverse shear stress is less than the "combination" shear strength of the specimens,identified the "combination" with the shear strength of filling body itself can resist roof in the sinking process of turning on the transverse shear damage caused by the wall.(3)FLAC3D simulation software was used to conduct numerical analysis on the strength of the "support layer",the width of the backfill and the height of the "top layer" of the "combined" backfill body.The research results show that the stability of surrounding rock is proportional to the strength of the support layer and the width of the backfill,and there is an optimal coupling height with the height of the top layer.Based on the mechanical properties of coal and rock mass at 2603 working face,the width of "combined" backfill,the strength of "top layer" and the layered height of backfill were determined by numerical analysis.(4)In supporting technology support for lane caused by inadequate strength of the large deformation of roadway surrounding rock puts forward three kinds of reinforcing supporting scheme,and using numerical simulation software FLAC3 D numerical analysis of three kinds of schemes,working face mining move pressure effect and supporting effect of "combination" filling body determines the optimal supporting scheme,and further proves the "combination" filling the effectiveness of the stability of roadway surrounding rock control.(5)The research results have been successfully applied to the 2603 working face of Zhangcun Coal Mine,through monitoring the surface displacement of the roadway,the stress load of the anchor cable,the strength of the backfill and the gas concentration in the gob retaining roadway.The monitoring results show that the application of the "combined" backfill body can effectively control the deformation of surrounding rock and the concentration of gas in the roadway,and realize the safe and efficient production of the stoping face.There are 66 figures,17 tables and 93 references in this paper...