Analysis Of Surrounding Rocks Movement On Longwall Large Height Mining Method Along The Strike In Steeply Dipping Seam

Steeply dipping seam longwall large height mining has reported less in the country, andnow the steeply dipping seam working face whose thickness more than3m all use fullmechanized mining.The low top coal recovery rate, poor coal quality, low mining efficiency,complex processand other issues have not been possible to get a better solution. The supportand surrounding-system stability control theory needs to be further improved. Therefore ithas important theoretical significance to solve the above-mentioned problem through studyingrock migration law of steeply dipping seam longwall large height mining.Through the similar material simulations, numerical simulations, and theoretical analysis,The rock migration law of Xinjiang Aiweiergou25221working face with large mining heighthas been systematically studied. The result shows that:(1) the initial weighting step is42.5m,the cycle weighting step is11m, and the cycle of the roof pressure step has a trend ofdecreasing with the mining height increasing.(2) results from the numerical simulations ofdifferent mining height shows that the mechanical characteristics of surrounding rock areasymmetric, which expresses as the upper part of the roof stress along the face tendency is lessthan the stress of the lower region of the roof and the bottom plate therewith vice versa, andthe displacement characteristics of surrounding rock performs that the vertical displacement ofthe face of the central region is the largest, less the upper region, followed by the lowerregion of the bottom, and with the increase of mining height, the displacement is increasing.The failure characteristics of surrounding rock is presented to plastic failure, roof and floortensile failure, upper and lower port shear failure, the support load distribution characteristicsperforms that a greater load to tilt the bracket in the upper region and the next step, the upperregion of the bracket load change, and stent has a the obvious forward pouring trend of, theincreasing mining height, also increases the amount of displacement of the stent was poured.(3)the main factor of the wall slabbing is that the peak pressure shift sin ward the working facewith the mining height increasing, and vacant roof to break up the rear a large rotary motion of coal wall double shear failure.Field practice shows that theoretical and experimental analysis accord field practice, andachieved good economic and technical benefits.