Mine Pressure Behavior of Horizontal Section Top-coal Caving in Steep and Ultra Thick Coal Seam

In order to make clear the mine pressure behavior of horizontal section top-coal caving in steeply inclined and ultra thick coal seam, the structural model of overlying strata which determine the mine pressure behavior of the mining face is established ; Also, the movement of overlying strata, horizontal and vertical displacement in the process of excavating different sections are analyzed by 3DEC simulation; Moreover, borehole stress meters were used to monitor the abutment pressure in the field. The results show that: with excavation towards the deep section, the basic roof breaks and form the structure of articulated beam, determining the pressure behavior of working face. Failure of the structure generate big vertical and horizontal stress resulting in the deformation of roadway; The pressure along the direction of the working face is not symmetric, deformation of the roadway near the roof is bigger than that near the floor; In shallow mining section ,the pressure behavior is slight and in deep mining section, there exist periodic roof pressure and the period is short; The concentration coefficient of abutment pressure and the influenced scope is small, compared with the gently inclined seam.