Research And Its Application On Repeaded Mine Strata Pressure Law In The Old Mining Area Of Thick Coal Seams

A large number of coal resource exist in the old mining area of thick coal seams by the out-dated coal mining method such as "dig top left bottom behind", and so on. Therefore it is vital to study the repeated mining strata pressure law and its application to guide the similar residual coal repeated mining practice. The main conclusions are behind:(1) With the help of numerical simulation method, the different span residual cavity roof collapse and residual roof stress of with different width coal pillar and depth of floor plane are given certain conclusion. Both ways are consistent with the result. The influence of abutment pressure is about 13m, width of plastic zone is 4-5m, the pillar big than 5m will gradually increase transfer more with increase of width of pillar. The transfer impact angle get by doing the tangent in the edge of coal pillar when the stress concentration factor is 1 in the contour map.(2) Consider two kinds such as the state of coal pillar and the state of empty goaf, the calculation of the Support Force and Working Resistance of support is announced by considering the pillar width, the advancing and roof coal and rock properties and other factors.(1) Its mathematic formula of the support force of support under state of coal pillar is P0=(Lc+LD)·hz·γz·LR(2) Its mathematic formula of the working support force of support under state of coal pillar is:(3) Its mathematic formula of the working residence of support under state of gob is:(4) Its mathematic formula of the working residence of support under of caved empty gob is:(3) By using the V-SVM(Support Vector Machine) to predict the mine pressure, it shows that the predicted value and actual value are basically identical, this suggests that V-SVM can completely predict the rock pressure.With the good achievement in 2107 re-mining work face of Han Ju coal mine. It verifies the strata pressure of re-mining the thick coal seams in the old mining area of the thick coal seams, and the re-mining Sci-Tech is feasible to improve the coal resource recovery rate.