Surrounding Rock Deformation Characteristics And Control Technology Of Gob-side Entry Retaining Within The Lower Layer Of Deep And Close Distance Coal Seams In Zhongxing Coal Mine

In order to optimize the connection between mining and excavation and improve the recovery of coal pillar resources,the application scope of gob-side entry retaining with pillarless coal in coal mines continues to expand.However,as the depth of mining increased,the in-situ stress continues to increase,especially under the condition of close-distance coal seams.Under the combined action of multiple mining stress and deep well high stress,it is difficult to control the stability of gob-side entry retaining.The stability control of gob-side entry retaining under complex conditions in deep wells has become an urgent problem to be solved.In this paper,aiming at the stability control of gob-side entry retaining along the lower layer of the typical deep and close-distance coal seams group in Zhongxing Coal Mine,comprehensive use of on-site investigation,experimental testing,numerical simulation,engineering practice and other methods are used to study the physical and mechanical properties of coal samples in the close-distance coal seams group.Surrounding rock deformation characteristics of gob-side entry retaining in the lower layer of deep and close-distance coal seams,the control advantages of the integrated control technology of cutting roof,anchoring and grouting for the surrounding rock of gob-side entry retaining in the lower layer of deep and close-distance coal seams,optimization of key parameters of the integrated control technology of cutting roof,anchor and grouting,field engineering test verification,the main research results are as follows:(1)Based on the gob-side entry retaining in 3203 headentry of Zhongxing Coal Mine,the deformation characteristics of gob-side entry retaining in the lower layer of the typical close-distance coal seams group are comprehensively reached,which field measured and investigated from the two aspects of roadway section deformation and support structure failure characteristics.(2)The numerical model of the integrated technology of cutting roof,bolting and grouting under the conditions of gob-side entry retaining in the lower layer of deep and close-distance coal group mining was established,and key parameters of technical scheme with cutting roof,bolting and grouting integration was researched by simulating and optimizing.(3)According to the production geological conditions and numerical simulation parameter optimization results of the gob-side entry retaining in 3203 headentry of Zhongxing Coal Mine,the on-site implementation plan of the integrated control technology of roof-cutting,anchoring and grouting was determined,and industrial tests were carried.The paper has 80 pictures,17 tables,and 86 references.