Abstract: Affected by variable angel, deformation, damage and movement of overlying strata in fully mechanized caving working face are more complicated than that in steeply dipping seam, which is exemplified by working face 120210 in Zaoquan coal mine. Based on its mining condition, a comparative study on movement of overlying strata respectively in steeply dipping working-face with variable angel and that with single angle is conducted through both similar simulation and field monitoring methods. The research has shown that 1) The movement law of overlying strata under different inclination angle in working face 120210 is crucially different from working face with single angle; 2) The overlying strata in the upper region with 26° angle has similar migration characteristics with inclined coal seam, the main roof in which region breaks and moves by cantilever beam structure with uniformly distributed roof pressure that values 23.7 MPa on average; 3) With an angle of 44°, the overlying strata in the lower region has similar migration characteristics with steeply dipping coal seam, and the caved rock slipped along dip direction and filled the gob; 4) The average roof pressure is 29.5 MPa, but it distributes non-evenly and varies in a large scope; and 5) As a critical transition section between the upper region and the lower region, the middle region posses overlying strata movement law of both inclined seam and steeply dipping seam. The average roof pressure in this region is 27.15 MPa and distributes evenly. The surrounding rock control principle is put forward according to the overlying strata movement property and ground pressure apparent feature in different regions. And a sub-regional method is proposed to control top-coal caving quantity according to this principle.

Key words: steeply dipping seam, angle-varied workface, fully mechanized caving, similar material simulation, overlying strata movement characteristic