Research On Overburden Strata Movement Law Of Full-mechanized Caving Face In Changshanzi Steeply Dipping Coal Seam

The laws of the deformation, failure and migration overburden strata are complicated during fully mechanized caving mining in steep inclined seam process, which has a significant effect on the controlling support stability. Thus, to provide evidences for the stability controlling of support equipment and lay the foundation for safe and efficient mining on subsequent mining face, the movement law of the overburden strata and the “roofsupports” system stability are studied and analyzed. Site-measurement, numerical simulation, similar simulation and theoretic analysis experiment are complex used in this paper to study overburden caving morphology, characteristics of stress distribution, changes of displacement law and control powered supports instability of No. 1123 face. The results indicate that:During the fully mechanized caving mining in steep inclined seam process, the roof pressure appears to ease. The compressive strength of middle roof is larger than the top and the low roof. The periodic weighting is smaller than others. And the periodic weighting of middle roof is less than that of upper and lower roof. Roof movement shows the time synchronization and the unbalanced characteristics of stress. Along the trend direction of the coal mining face, the main roof caving experiences fixed beam structure, arch structure, and cantilever structure. In the tendency of coal seam, separation occurs first at the upper position(0.53l) of roof beams and then tensile failure generates, resulting in an upper region offset of roof caving form and an asymmetric arch. The roof caving under the action of the caving coal gangue and its structure eventually becomes the arch structure upper the face, and the middle and lower roofs represent the caving form of girder structure. The surrounding rock stress distribution presents symmetrical arch characteristics along the trend of coal seam and presents symmetrical arch characteristics along the tendency of coal seam. The influence degree of mining face on the roof is greater than floor, and the roof damage is more serious than floor and the maximum displacement appeared on middle upper coal mining face. The movement of overlying strata significantly concentrates on the regional of middle upper coal mining face along the inclined direction, leading to this area load measuring of powered supports variable and easy instability.According to the deformation, the coal seam in Chang Shanzi full-mechanized caving coal mine face of dipping seam, practicing and experimental research are used to master the movement law of overburden strata and working characteristics of supports in No. 1123 face. The support design, production technology and practical foundation for the protection of the support self-stability are recommended. The supports of working face are monitored sub-regional, sub-time mainly. So control of the single factor caused by the instability of supports is formed, the working face is guaranteed to be safety in production basically.