Surrounding Rock Control Technology For Gob-side Entry Retaining In Legacy Pillar Of Qin Xin Coal Mine

The technology of gob-side entry retaining was very promising which was conform to the requirements of green and scientific mining.Surroundings distortion and the change of stress field is complex in legacy pillar by using gob-side entry retaining.Based on the analysis of predecessors’ achievements and by comprehensive using of theoretical analysis, numerical simulation and the method of industrial test, this thesis analyzed, the characteristics of gob-side entry retainingand control technology of surrounding rock of gob-side entry retaining. Research results are summarized as follows:Based on analysis of the rupture rule of main roof of gob-side entry retaining in legacy pillar between two goaf,the stability conditian of section pillar was put forward.More detailed analysis was conducted on distribution law of plastic zone and the vertical stress distribution of the different winth pillar under the influence of the two working face mining.Then Then the characteristics of the stabl pillar’s vertical stress distribution was “saddle”.The reasonable width of the pillar was 20 m, tested by theoretical calculations.Under the condition of reasonable width section pillar, the stress evolution law and deformation regulation of the pillar was analyzed on the influence of the advance and hysteresis of two coal mining faces.Loading and unloading law of the surrounding rock of gob-side entry retaining in legacy pillar was summarized, which provides the basis for roadway-in support determination of gob-side entry retaining.Based on analysis of loading and unloading law of the surrounding rock of gob-side entry retaining in legacy pillar,the control technology of roadway-in support which included high pre-tightening force and high strength anchor with cable was determined.According to the surrounding rock subsidence, reinforcement technology was put forward,which worked together with roadway-in support.Research results above were applied successfully in Qinxin colliery,and provides the reference value and foundation for other similar conditions.