Theoretical analysis of support stability in large dip angle coal seam mined with fully-mechanized top coal caving

Support stability is critical to ensure fully-mechanized top coal caving of large dip angle coal seam. To obtain the relations between each factor and hydraulic support stability, the mechanic model of large dip angle coal seam along face dip and strike was built to analyze support stability, including antitoppling, anti-slip, and anti-rotation of supports. The result indicates: Along the face dip, the suport stability was negatively correlated with dip angle; Higher top caving means lower anti-rotation at suport tail; With initial support force and working resistance of supports enhanced, the anti-slip, and antirotation stability of supports can be risen significantly. Along the strike, the critical toppling angle was proportional to dip angle, mining height, support weight, support width and support force; The critica slip angle was positive correlation with support force, friction coefficient of roof and supports. According to the results of both mechanical analysis and engineering projects, support stability in large dip angle can be risen efficiently and supports slipping, toppling and rotation can be avoided by selecting proper technical methods and equipment, like enhancing initial support force appropriately.