Hydraulic support and coal wall coupling relationship in ultra large height mining face

In terms of the hard and thick coal seam occurrence conditions in Jinjitan coal mine,the 8. 2 m ultra large height longwall mining method was proposed,and the strength,stiffness and stability coupling relationship between the hydraulic support and wall rock in the ultra large height longwall mining working face were analyzed. The hydraulic support of ZY21000 / 38 / 82D and newer structures were successfully developed. Based on the coupling relationship be- tween the hydraulic support and wall rock,the double-factors control method for confirming the hydraulic support work- ing resistance in ultra large height longwall mining face was studied by theoretical analysis and numerical modeling. Through building the “tensile-slippage” mechanical model of coal wall spalling for hard fragility thick coal seam,the critical face guard force of hydraulic support was obtained to control the coal wall sliding instability. The influence and controlling method of the pin roll gap to the hydraulic support stability were analyzed. Through innovating the new structures of the double-telescopic prop and three-grade coordinate face guard device,the stability control of hydraulic support and coal wall system was guaranteed.