Study On The Law Of Strata Behaviors In Mining Steeply Inclined Coal Seams

In the past years, due to the needs of national economic and social development, those coal seams with good occurrence conditions and little mining technology were needed were encouraged to exploit in the first.So the research of mining pressure of steeply inclined coal seam had not been taken seriously.When the mining pressure and strata control of nearly horizontal seam and gently inclined coal seam has formed a set of theory and frameworks, the research about the steeply inclined coal seam just begin. In recent years, due to promoting sustainable development of the country, and the encouraging development of energy-saving, those coal seam with bad occurrence conditions such as thin coal seams, steeply inclined seams, also need mining efficiently.In this dissertation, focuses on the real physical model of steeply inclined coal seam, using elasticity analysis, numerical simulation and similar simulation to research the basic law of mining pressure of steeply inclined coal seam. The main contents as follows:(1) Aiming at the particular occurrence conditions of steeply inclined coal seam, under the conditions of primary mining and normal mining, assuming that their basic roofs are the model of thin plate, boundary conditions are four boundary fixed and three boundary fixed with one simply supported respectively, these plates are isotropy, and the loads of overlying strata was decomposed in two directions, one is perpendicular to the plate and another is parallel to the plate. In addition, analyzing their stability from the view of energy, getting the point that when the lateral load exceeds the critical load, plates will change from the plane of the balanced steady state into the non-stable state, in the end, with the effect of longitudinal load, turning into another balanced curve state. Finally, using the board’s theory of elasticity, the critical load was solved, compared with the weight of the overburden load along the dip direction, getting the Initial breaking criteria and cycle breaking criteria of basic roof. With the mining depth increases and seam inclination increases, both the drawing pace of the Initial breaking and cycle breaking of the basic roof will be reduced.(2) Based on the modern rock mechanics and mining engineering practice, regarding the surrounding rock system as a layered elastic-plastic medium, and assuming that this medium is a layered isotropic, the whole surrounding rock system was simplified as a plane strain model, using the finite element program to split and calculate it, in the end, the calculated results were processed to analyze stress distribution of the roof of steeply inclined coal seam, and the result is compared with the result of similar simulation. (3) According to the geological conditions of Luan group in Shanxi province and the coal occurrence conditions, using similar simulation test methods, the test model frame that has been developed by Taiyuan University of Technology was used to simulate the five coal seams. Using varies kinds of methods to mining according to the different thickness of the coal seam, coal mining strictly in accordance with time similar ratio. Using a digital camera to observe the breaking and bending of the basic roof, combine with the camera records of the displacement of each level of each section in the mining process and after the excavation, analyzing commonality and particularity of the basic law of mining pressure of steeply inclined coal seam.