Abstract: To solve the surrounding rock control problem of open-off cut with large section and thick coal roof, the simulation software FLAC3D has been firstly used to study the effect produced by the thickness of coal roof and width of open-off cut on failure characteristic of surrounding rock. The result shows that the coal roof plastic zone is on the shape of rectangle when the coal roof thickness is less than 6 m, and arch when the thickness is more than 6 m. Besides, with the growth of open-off cut width, tensile failure area of roof approximate linearly increases from 4.5 m2 to 14.5 m2. Furthermore, the demarcation point of subsidence speed in roof rock moves up from 4 m to 8 m that are away from open-off cut roof. Then, on the basis of above research, the reasonable configuration is studied by means of mechanical theory analysis, and the jointed "cross stride" control technique is put forward as well, which achieves successful application in field.

Key words: thick coal roof, large section, FLAC3D, anchor cable configuration, stability analysis