Analysis on jammed mechanism of hydraulic powered supports in high intensity coal mining face in shallow depth seam with thin base rock

In order to solve the hydraulic powered support jammed difficult problem caused by a large area roof cutting and falling along thecoal mining face under the high intensity mining influences ,the numerical simulation and theoretical analysis were applied to analyze the o-verburden strata failure process and disaster occurred mec hanism during the coal mining face pushing forward process. The results showedthat during the seam mining and excavation process,the distribution difference of the stres ses in different lithology strata would be high andthe breaking and falling conditions also would be different. The upward cracks and downward cracks in the overburden str. ata were devel-oped at the same time and the run-through were the prerequisite of the catastrophe occurred. The load of the overburden strata could transitthe variation of the factors,the basic roof could break the rock block and then cut the rock block, the thick aeolian sand existed on the sur-face ground and watery sand affected to the brok en rock block movement mode of the basic roof would totally increase the probability to thehydraulic powered support jammed disaster occurred by the large area roof cutti ng and falling down along the coal wall. The mining heightincreased and the length of the broken rock block would be reduced and the basic rock structure would appear in a single key block only.The paper explained the cause the cutting and falling phenomenon easily occurred by the basic roof structure. Finally the paper analyzedthe partial powered supports jammed accident occurred in No. 31402 coal mining face of Wulanmulun Mine.