Stability Control Technology Of Surrounding Rock In Shallow Burial Gob-side Entry Of Kubai Mining Area

Xinjiang,as a large-scale coal base of strategic importance in China’s development plans,plays a vital role in ensuring the country’s energy security.Among them,the Kuibei mining area is rich in coal resources,with a wide variety of high-quality coal,making it an important production base for coking coal in Xinjiang.However,the traditional longwall mining method often utilizes the practice of leaving coal pillars to maintain tunnel stability,which can lead to resource waste or stress concentration.In response to the issues arising from pillar extraction,this study focuses on the shallow buried coal seams in the Kuibei mining area.It employs a comprehensive approach that combines theoretical analysis,numerical simulation,and on-site engineering practices.By taking the roof strata composition of shallow buried coal seams in the Kuibei mining area as the starting point,a mechanical model is established to study the top-coal caving process along the goaf with different roof structures.The study derives the support resistance of different roof structures and investigates the influence of various top-coal caving parameters on the deformation and stress distribution of the surrounding rock in the roadway,aiming to determine the optimal top-coal caving parameters.Additionally,a reinforced support scheme is designed for the secondary extraction stage of the working face,proposing stable control techniques that are in harmony with the selected top-coal caving parameters.The research findings are validated through practical application in the field to verify their reliability.The main research conclusions and achievements are as follows:(1)Based on the investigation and analysis of the structural characteristics of the roof in the shallow coal seam of the Kuibei mining area,the roof structure was classified into three combinations according to the spacing between the old roof and the coal seam:thick direct roof-old roof type,thin direct roof-old roof type,and coal seam-old roof type.Different basic roof rock collapse mechanics models were established for the various roof structures,and it was found that the resistance force P of the roadside support and the overhanging length L of the basic roof rock were positively correlated.(2)The study focuses on a typical thin-layer direct roof working face,specifically the upper section of the Yushuquan coal mine in the Kuibei mining area.Numerical analysis models are established under different top-coal caving heights and angles to investigate the impact of these parameters on the strata movement,deformation of the surrounding rock in the roadway,and stress distribution.The results indicate that with increasing top-coal caving height and angle,both the stress and displacement of the surrounding rock in the roadway show a trend of initially increasing and then decreasing.Combining the numerical simulation with theoretical calculations,it is determined that a top-coal caving height of 10 m and an angle of 15° result in the optimal unloading effect,effectively controlling the stability of the surrounding rock in the roadway.(3)Based on the optimal cutting height and cutting Angle,the numerical simulation model of secondary mining along goaf retaining roadway was established,and the changes of stress and displacement in stope with variable length of working face were analyzed during the two mining processes,and the stress distribution and displacement evolution law of working face before and after primary mining and secondary mining with variable length were obtained.The stress concentration degree and roof displacement of roadway surrounding rock are more obvious in the second mining stage due to the repeated disturbance.As the length of the working face increases,the stress peak and roof displacement increase accordingly.Therefore,the one-off mining support scheme is not enough to maintain the stability of the roadway.Therefore,it is necessary to design a support scheme to maintain the stability of the roadway at different mining stages.(4)In response to the stress distribution in different mining stages,enhanced support schemes are proposed for the goaf area in the roadway.The study investigates the deformation characteristics of the surrounding rock in the roadway under different support schemes during various mining stages.For the goaf area in the roadway,a support scheme consisting of "double-row reinforced anchor cable + anchor rod" is employed.This support scheme,combined with top-coal caving to relieve pressure,meets the requirements for safe extraction of the working face.(5)Based on the specific geological conditions of the goaf area in the Yushuquan coal mine,a support scheme consisting of "double-row reinforced anchor cable +anchor rod" was designed and implemented.The monitoring plan for the deformation of the roadway during the extraction period of the working face indicates that there were no significant side bulges in the goaf area of the roadway,and the solid coal pillar did not exhibit noticeable fragmentation.The support scheme effectively met the safety and operational requirements,demonstrating excellent engineering application results.This thesis includes 66 figures,2 tables,and 94 eferences.