Surrounding Rock Control Mechanism And Application Of Gob Side Entry Driving With Small Pillar In Inclined Coal Seam Of Panzhihua Coal Mine

Panzhihua coal mine No.7 coal seam is the main coal seam of the mine,with an average dip angle of 30°and a buried depth of 200-240 m.This paper takes the return air drift of 11074 working face of the mine as the research object,analyzes the deformation and instability characteristics of the outer section of the roadway through field investigation and laboratory test,and carries out theoretical analysis,formula derivation and numerical simulation around the width of coal pillar Then the width of coal pillar is determined.Based on the deformation characteristics of surrounding rock of the roadway,the control technology and scheme of surrounding rock of 11074return airway are put forward,the research results are applied in the field,the conclusions are as follows:1)Combined with the rock sample and bolt mechanical parameters test,the uniaxial strength of rock and bolt ultimate strength are obtained,which provides a good reference for the development of subsequent numerical simulation and the proposal of support scheme;the development of roof cracks is understood through drilling peep technology,and the main causes of roadway instability are obtained according to the field investigation.2)Based on the geological conditions of the mine,the paper summarizes the failure characteristics of overburden in inclined coal seam.By establishing the roof structure and the mechanical model of coal pillar,the minimum width of coal pillar should be reserved in 11074 return air drift is determined as 4.8 m;meanwhile,the stress,displacement and plastic distribution law of surrounding rock under different width of coal pillar are studied and analyzed by FLAC^3Dnumerical simulation software,and finally reasonable distribution law of surrounding rock is determined The width of small coal pillar is 5 m.On this basis,through the simulation analysis of single geological factors,the mining depth and the lateral pressure coefficient are obtained.3)The surrounding rock control technology of"high strength bolt+long and short anchor cable echelon support+anchor cable beam+steel belt"is proposed.The two different schemes of"pure bolt"and"high strength bolt+long and short anchor cable echelon support"are simulated by FLAC^3D.The results show that the latter is more conducive to the stability of gob side entry.From the perspective of bolt cable cooperative support,the bolt anchor model is obtained through theoretical calculation The formula of cable pre tightening force matching degree and the best matching value,and then through the field measurement,the law of pre tightening force loss is obtained,and the problem of pre tightening force loss can be solved by secondary pre tightening;in addition,through the simulation analysis of different bolt row spacing,bolt length and existing support scheme,the support parameters of the roadway are determined.4)Industrial application was carried out in 11074 working face of the mine.The results show that:setting 5m small coal pillar and using the existing support scheme can effectively control the deformation of surrounding rock,ensure the stability of surrounding rock of 11074 return airway,so as to solve the problem of repeated repair of the roadway,achieve the goal of rapid excavation and efficient support,and provide reference for the safe mining of coal resources under similar conditions.This paper has 60 pictures,16 tables and 94 references.