Numerical Analysis Of The Influences Of3-1Coal-Seam Mining On The Segment Structure Of An Inclined Shaft In XinJie Area

TBM method, with developed theories as well as a wealth of construction experience, has been widely applied to various fields of tunnel construction at home and abroad. Yet it is the first time interiorly that a main and a side inclined tunnels transportation are been built based on TBM (Tunnel Boring Machine) method in coal mine filed. The paper is focused on the technical matters of TBM method’s application in the coal mine construction, based on the inclined shafts in the Inner Mongolia’s XinJie area.The geological environments of coal field of XinJie area is complicated. It pass through several aquifers with average thickness of327.56meters and with good water permeability. Thus, the inclined shafts is excavated by TBM, and supported by segment structure. Its inclined length is6558meters, with oblique angle of6°and the thickness of350millimeters. The bottom end of the shafts is the floor of3-1coal-bed, connecting with the main roadway in the central coalfield.For exploiting with the fullest extent, and controlling the adverse effect, estimation of a logical inclined shafts for the protection of size of coal wedge is needed. While empirical formula could only roughly deal with the geometric parameter and mechanical property of the coal seam, numerical simulation, on the other hand, could take into account of the coal seam, rock stratum, geometric parameter and mechanical property of the inclined shafts all at the same time. This article studies the different location of the stratum and the inclined shafts, with the calculation by the explicit finite-difference program FLAC3D, and get the research findings as follows:1. Based on the two dimensional solid mechanics model, with the model geometry relationship unchanged, width of the protective coal pillar is the most influential factor to the segments, followed by the rock stratum elastic modulus variation, rock stratum cohesive strength and the change of friction angle. With the other parameters unchanged, the greater the distance between the floor of inclined shafts, the less influence the mining has to the segments.With the change of modulus of the protective coal pillar and the reinforced area as the reinforcement measure, the more modulus and the reinforced area increase, the more the axial force and the bending moment decline.2. Based on the three dimensional solid mechanics model, with the width of the coal pillar increases, the segments’negative axial force and the bending moment decline. But when the width reach a certain line, the segments’negative axial force and the bending moment will be stable in a small range.The displacement angle of strata variation effects less of the segments’axial force and the bending moment, but more of the segments’ displacements. With the displacement angle of strata increases, the segments’ maximum displacement slowly increased first, then rapidly.3. Based on the three dimensional Fluid-solid coupling mechanics model, The computed results predict that seepage flow gives more damage to the segments’force and displacements. Furthermore, the more permeability times groundwater flows, the greater the impact of segments’ displacements. Therefore, in the actual projects we must give more attention to seepage effect.4. The calculation has led to the result of the critical radius of curvature of the tunnel’s longitudinal displacements, which will affect bolts’ working position, as elastic state, plastic state and failure state, according to the "Duct’s longitudinal rigidity" theoretical formulas and the actual parameters of XinJie mine. Based on the results of FLAC3D, only coal mining has little influence on non-uniformity displacements. But when considering the local seepage around the tuunel, the tunnel’s longitudinal non-uniformity displacements will be greatly effected, some of the bolts will be working on the plastic state.