Study On The Thickness Of The Top - Of - The - Road In The Underground Mining Of 3-1 ~ # Ore Body In Maanshan Coal Mine

In the latter part of the open pit mining, many mines are facing a transition problem that how the open-pit mining can transit to underground mining. From the open-pit mining to underground mining is a complex transition process, will encounter many technical problems. Especially in the mine which use the opens tope method to exploit the first bed ore body. The technical and safe problems include the boundary pillar stability, underground pressure, preventing spontaneous caving and inrush, etal. All of these technical problems must be careful analysis and argumentation, and then make feasible plan before the transition from surface to underground. Due to the low recover and large losses, if we leave the natural realm pillar, a large number of permanent resources will be wasted. So, it is particularly important to do the research to ensure the sustainable development and safe production of the mine open pit to underground mining.In this paper, the slope stability of open-pit and the feasibility of the composite people pillar instead of the nature pillar will be studied and analyzed. Based on the result, feasibility program was established to instruct mining. The main work of this paper will include the following aspects:(1) Depend on the geological findings and indoor rock mechanics test site, based on the H-B Standards, the mechanical parameters of Maanshan Iron ore No.3-1ore body will be determined.(2) Based on the analysis of the factors affecting the stability of Boundary Pillar and the Mechanical mechanism of instability Boundary Pillar in Open pit to underground mining. And a preliminary analysis by the method of the stress situation elasticity mechanical model of Boundary Pillar has been conducted. At the same time, the initial pressure theory has been used to analysis the value obtained under the cover soil thickness Security Boundary Pillar.(3) According to the occurrence status and the situation of mine ore body, established a numerical model whitch is consistent with the Maanshan Iron ore No.3-1ore body transition from open-pit to underground mine practical engineering.Use the numerical simulation method to determine the thickness of the mine open pit to underground mining safety realm top of the column.(4) Against the problem of the big loss and low recovery of the nature Boundary Pillar, on the basis of research and reference relevant literature, This paper presents a method which use reinforced concrete pillar structure instead of the traditional natural Boundary Pillar. After a detailed analysis of the technical and economic aspects of the comparison, take the idea that the method is safe and feasible.In this paper, summed the state to solve the open pit to underground mining methods roof pillar design problems, broaden the idea of how to leave the boundary Pillar in open pit to underground mine, has a certain practical significance.