Strata Behaviors Of The Fully-mechanized Working Face At The End Stage

For the Fully Mechanized coal mining technology, working face moving is an important link in achieving high yield and high efficiency. Due to the impact of mining, the roof ofequipment remove gateway moves significantly and the displacement of the two sides will significantly increase. Therefore it is very easy to occur roof caving and serious rib spalling and other problems, even cause the break-offs which affect the regular productio n of the mine. Base on the thorough understanding of the mine pressure regularity which under the influence of dynamic pressure, the paper determines the most favorable failure forms of the equipment remove gateway roof and studies the mechanism and applicable conditions of different strata pressure control measures. The main contents and conclusions as follows:(1) The distribution of pressure of equipment remove gateway surrounding rock is divided into three phases, which include roadway drivage stage, effected by the dynamic of mining and the working face through stages. Based on the elastic-plastic theory, determined the starting distance of being effected by the dynamic of mining.(2) when the main roof faults before the working face and never faults again after that, the roadway in a relatively stable stage while the supports are affected by the relatively slightly, which shows that the roof failure form is favorable for the stability of the roadway. After further analysis, presents the formula of roof fracture reasonable position, which provide the theoretical basis for the target pressure control in the end stage of mining.(3) Established a reasonable model and analyzed the stress and deformation of the main roof- immediate roof coupling deformation system and derived out the function relation of the periodic weighting interval. Through the analysis, the main influence factors include the main roof elastic modulus, the main roof thickness, the immediate roof elastic modulus, the immediate roof thickness, The tensile strength of main roof and the overlay stratum thickness.(4)Based on the analysis the pressure data of 14204 fully mechanized face in Zhang JiaMao, obtains the regression curve of periodic weighting interval and the recovery rate, the results showed that the periodic weighting interval with recovery rate increase has increased,but the roof working face ends and the middle position of the boundary conditions, geological conditions not the same, so the increases range of periodic weighting interval is different.(5) Established the mechanical analysis model of un-mined coal pillar in terminal mining.According to the model obtained the coal pillar width function relation of eleven parameters which divided into three kinds including critical occurrence conditions and the mechanical parameters of surrounding rock, engineering parameters, the destruction form of main roof before transfixion. The results show that he main influence factors include the fault location of main roof, the overlay stratum thickness, the nature of the strata and the mining height.Because different control measures applicable conditions of the special, in the late stage of recovery should take reasonable measures to control the coal mining based on the actual fault conditions of the main roof.The study provides useful experience for withdrawing in fully mechanized mining technology and enriches and develop the mining pressure control theory.