Abstract: Open-off cut along gob area of fully mechanized caving face has the characteristics of large span, large thickness of top coal, small coal pillar along gob area, soft surrounding rock and fracture development, so, its support is difficult. In this paper, in view of the open-off cut along gob area with 8 m in width, and 5.6 m in thickness, by using theoretical analysis, numerical simulation, field test and monitoring analysis, the remaining principle of coal pillars and pillar stress distribution characteristics were studied, and the coal pillar width was optimized. In addition, the support mechanism of open-off cut along gob area was analyzed, and the supporting schemes including the anchor net belt combined with anchor cable, and the anchor net belt with truss and anchor rope were designed and tested. The results show that the rational width of coal pillar is around 4~5 m, and the two supporting schemes of anchor net belt combined with anchor cable and truss and anchor rope, respectively, can improve the forced state of top coal and the bearing capacity of surrounding rock, effectively control the bed separation, fracture propagation, bending and subsidence of large span and thick top coal, and ensure the stability of open-off cut along gob area of fully mechanized caving face.

Key words: fully mechanized caving face, open-off cut along gob area, coal pillar width, support mechanism, anchor net belt with anchor cable, truss and anchor rope