Study on the reasonable tunnelling position and supporting technology of the roadway in isolated coal pillar of thick coal seam

Aiming at the problems that surrounding rock of the roadway in isolated coal pillar were deformed seriously and difficult to maintain, which caused by improper position and support technology. Based on the engineering background of a mine in Xinjiang, the stress distribution law of the isolated coal pillar and the deformation characteristics of the surrounding rock were analyzed by the method of numerical simulation. It was found that the width of stress reduction area which located on the side of the second coal face is larger than that of the first one. And, the surrounding rock deformation of the roof and coal side which located near the wide coal pillar is significantly higher than that of located near narrow coal pillar, which distributes homogeneously. According to the theoretical calculation and numerical analysis results, the reasonable tunnelling position of the test roadway was determined to be in the side of the 5 301 gob area to keep 4.0 m narrow coal pillar, and driving along the floor. At the same time, according to the characteristics that non uniform deformation of surrounding rock of the roadway in isolated coal pillar and the isolated coal pillar was crushed seriously, the asymmetric supporting technology was invented, which consist of lengthen anchorage by high strength thread steel bolt and reinforced support at the key position by anchor cable. Through engineering practice, the validity of this method and technology was proved.