The Research On The Reasonable Size Of Coal Pillar In Steeply Dipping Seam

With the rapid increase of mining technology of coal resources and nearly horizontal and gently inclined coal seam mined in massively, coal resources, easily produced, are less than before. At the same time, people found that coal resources which abandoned due to difficult of exploiting are the scarcity of good quality and the varieties. The resource extent of high-quality coking coal and anthracite coal scarce accounted for more than half of the large dip angle coal seam. In order to ensure the continued supply of coal, and not waste the precious coal resources, large angle and even steep and complex geological conditions of coal mining are also included in the category. So the study of big obliquity seam mining supporting technology is very necessary. The key points of coal supporting are ensure that the coal mine supporting stope and roadway safety, coal pillar between two working face has important influence to maintain roadway and stope surrounding rock stability. Not only considering the mining safety, but also should take high recycling rate into account, so section coal pillar should be a reasonable width. What’s more, except for the width of coal pillar, the obliquity of coal seam, buried depth of coal seam also affect the stability of coal pillar. In large dip angle coal seam mining process, the stope roof mechanics is asymmetric, which is different to make coal seam with large dip angle strata destruction, caving rock stuffing and section coal pillar on both sides of the roadway by destructive condition with mining gently inclined coal seam. Therefore, in order to ensure the safety of large dip angle coal seam mining, we must base the fracture condition that overlying strata above the coal pillar and explore the reasonable size.On the Lu Ning Mengjiayao Coal mine No. 2 large dip angle coal seam as the research object, mainly study the No. 2 coal seam working surface of section coal pillar setting design theory and technology, and with the increase of the depth of coal seam, coal seam dip angles, the reasonable width of coal pillar. Research content and theory are as follows:(1) From the aspect of coal pillar suffering the load, pressure characteristics of large dip angle working face goof, roof initial and periodic broken structure and coal pillar by force have been researched. The stress distribution around the large dip angle, the position of the coal pillar under the maximum load and the most serious damage period were determined,(2)Combining the limit equilibrium equations and boundary conditions, the section coal pillar is divided into plastic zone and elastic zone. Angle factor is introduced; section coal pillar elastic plastic zone width is deduced. To determine the influence of section coal pillar elastic plastic zone width factors. Considering the impact of the extraction of coal pillar width and modifying the formula. According to the actual geological conditions of Mengjiayao No. 2 large dip angle coal seam to calculate the coal pillar width between two working surfaces in theory.(3) Using numerical simulation software to simulate the section coal pillar failure of 11202 and 11204 two working face in different width. Introduction of the elastic zone rate be as the index to quantify the stability of coal pillar, study the increase of the coal pillar width, section coal pillar by force and damage conditions to determine the rational width of section coal pillar.(4) According to the factors affecting the stability of coal pillar, the orthogonal test scheme of coal pillar has been arranged. According to range analysis, the each factor’s importance degree has been determined. Using variance analysis to verify the degrees, through the regression equation to determine the effect of each variable on the index, the relationship between various factors and the stability of coal pillar have been obtained. Fitting determined regression formula between the minimum width of coal pillar and the impact of various factors. On this basis, the fitting degree of the sample observation value is tested by the goodness of fit test. By using F test, the influence of the independent variables on the random variables is investigated.