Floor Failure And Slip Mechanism In Fully Mechanized Top Caving Face Mining Steeply Dipping Seams

The steeply dipping seam is defined by coal seam with pitch of35°~55°. When coalseam pitch is more than35°，the movement of surrounding rocks is different from that for coalseam which pith is less than35°．Seam floor is a subject to a variety of geological body injury,exploitation and then will be the role of the relevant mining influence mechanical damage,mining and pressure, it is necessary to grasp the damage slip rule.Numerical simulation, field observations and theoretical analysis is used to study stressdistribution, the horizontal and vertical displacement and plastic failure characteristics in thefloor of different dipping angle working face after mining. the characteristics of themechanical behavior of the floor is analyzed after mining with seam angle and variation ofbefore and after caving, and the effects of different propulsion to floor. The effect isindentified according to the measured pressure data of support caused by the roof caving,relevant factors and geological conditions affecting floor destruction and slip are summeddiscussed, and failure slip mechanism is obtained according to the analysis on the uniqueoccurrence environment of steeply dipping seams and mining process.Research shows that: the damage range, degree of displacement and displacement rangeof steeply dipping seams increases before and after caving, the maximum failure depths occurin front of the coal wall, rear of goaf and the upper and lower face ends, floor body failuredepth decreases with increasing angle increases, the damage the depth at the head of the faceis greater than the ends along inclination, the damage depth difference increases with theinclination angle increases. The mathematics mechanical model is established based on a semiinfinite body in mechanics of elasticity. Numerical simulation results show that vertical stress,along the strike, is symmetrical arch, and along the tendency is asymmetrical arch, verticaldisplacement has the characteristics of two kinds of arch. The data analysis showed that theupper support pressure of steeply dipping seams is lower than the pressure in the middle andlower support, and middle and lower pressure is approximately equal. Research indicates that: the floor failure and slip in fully mechanized top caving miningsteeply dipping seams is a complex process in which the floor coal and rock performancesduring fracturing, crushing and movement with the characteristics of time evolution and spotdifferences, and it is affected by geological conditions, mining factors, water, air and gascondition. The four type floor destruction and slip is summarized: fully surface failure,surface arc failure, triangle block failure type, square massive failure,6key technologies offailure and slip control is enumerated in steeply dipping seams.This study has certain reference value to the similar steeply dipping seams face whichmay exist failure and slip disaster and a certain guiding significance to control it in the miningprocess.