Study On Jinbaotun Deep Coal Mine High Stress Soft Rock Roadway Support Technique

With the increase of mining depth, the deep mine high stress soft rock roadway supporting and maintenance problem has become a serious problem in the underground engineering both at home and abroad. A single active support or passive support could not be able to effectively control severe deformation and continuous creep of roadways. The traditional bolt supporting technique is difficult to form a stable and effective bearing structure in the high stress soft rock roadways. And passive support forms although can significantly enhance the stability of shallow surrounding rock through the table function, it is unable to adapt to the strong deformation of surrounding rock, at the same time, it is difficult to make use of bearing capacity of deep rock mass. And finally large deformation and yield failure phenomenon could occur under high stress environment.Therefore, according to the deep mine high stress soft rock roadway research status at home and abroad and Jinbaotun N201 working face coal mine geological conditions, an approach which combines theoretical analysis, engineering analogy, numerical simulation and field industrial test has been put forward to study the deep mine high stress soft rock roadway supporting technique. The anchor net spray combining U-shape steel supporting technique was proposed and then successfully applied to the engineering practice based on the results of the study. The main researches are as below:(1) Field investigation is applied to adjacent N203 working face, the geological and mining conditions of N203 working face roadways, deformation and failure characteristics and the main influencing factors are obtained: deep coal seam buried depth, the roadway buried depth is about 800 m; roof and floor are thick mudstone, with low strength, large deformation under high stress properties, especially the floor heave phenomenon is extraordinarily large; large deformation of shallow surrounding rock, the original passive supporting scheme cannot control the large deformation of roadway surrounding rock;(2) According to Jinbaotun N201 working face belt roadway and ventilation roadway geological conditions(the belt roadway is adjacent working face and gob of N203, while ventilation roadway is adjacent both sides of the entity coal), FLAC3 D numerical calculation software is used to analyse reasonable coal pillar width of belt roadway and then gob-side entry driving is adopted, with the width of coal pillar 8 m;(3) Combined deformation and failure characteristics and theoretical analyses, the anchor net spray combining U-shape steel supporting technique is put forward, the parameters then have been simulated and determined by combing FLAC3 D numerical calculation software and theoretical analysis;(4) Industrial test has been conducted which indicates that the anchor net spray combining U-shape steel supporting technique has effectively controlled severe deformation and continuous creep of the belt and ventilation roadways. And comparing to original supporting scheme which should conduct overhauling the u-shape steel many times, the new supporting technique is both simple and convenient, and with high popularization value.