The Research On Longwall Inclined Slicing Of Top Coal Caving In Steeply Dipping And Extra-thick Coal Seam Of Dongxia Colliery

The coal seam in the No.37220 fully mechanized coal caving face of Dongxia Colliery Huneng Huating Coal Group Co.,Ltd has the characteristics of large inclination, big thickness, inflammable and complex structure.It has been result in short effective length, low capacity, low yield, higher drivage ratio per 10,000 ton,low stoping rate, serious resource waste and few profit by the horizontal section of the top coal caving.In order to achieve high yield and efficient,it has decided to adopt Longwall Inclined Slicing of Top Coal Caving in steeply dipping and extra-thick coal seam.This paper which has determined the reasonable sub-level caving mining scheme study longwall inclined slicing of top coal caving in the No.37220 fully mechanized coal caving face in steeply dipping extra-thick seam by theoretical analysis, similar simulation experiment, top-coal movement theory, strata control observation and field test.theresult shows that the average periodic weighting length of lower sliced face is longer than upper face,t downside is the first sequence,then midside,finally upside in time of periodic weighting in upper sliced face,the time sequence is midside,then upside,finally downside in lower sliced face and the working resistance of supports in lower sliced face is greater than that in upper face.The moving rate and motion quantity of upper top coal are more than lower top coal in normal and tilt direction with the advancing of upper and lower face.It will appear double funnel and wave fluctuation of coal caving quantity during caving from top to bottom,with little influence on top coal and overlying strata.No appearance of double funnel and greatinfluence on top coal and overlying strata during caving from bottom to top. Axis of ellipsoid,the funnel of coal caving and migration path of overlying strata is a plumb line. The reason of support instability such as tipping, sliding and tail twisting is empty roof over the support or suspending roof during advancing support, coal caving and gangue leakage during mining.Finally, two mining and one caving(drawing interval is 1.2m),from top to bottom and several times coal caving is adopt in the No.37220 fully mechanized face in steeply dipping extra-thick seam. Mining rate of lower inclined sliced face is higher than upper face. Field test has achieved good economic benefits.And,We put forward safety precautions on the basis of the rolling and flying gangue accident.