The Construction Behavior Of Coal-bearing Rock Tunnel And The Stability Analysis Of The Surrounding Rock

In the central and western regions in China are distributed most of the coal seriesof the country as the topography of it most likely mountain ridge. With the continuousdevelopment of our country’s economy, the deepening of the western developmentand the rise of central China strategy, in all kinds of traffic engineering has built andunder construction, have accounted for the proportion of large in the Midwest. Tunnelthrough the coal seam is much more inevitable in the traffic engineering for themountainous coal geology and it’s advantage in construction costs. In these tunnels,especially with horizontal coal seam how to select tunnel construction methods andthe stability of surrounding rock are crucial.Combined with the engineering example of Shi-tang tunnel, this paper firstprobes into coal series rock tunnel construction measures, secondly by adopting finiteelement software MIDAS GTS-with coal series rock tunnel segment for thetwo-dimensional elastic simulation, analyzed the distribution of different location anddifferent thickness of the coal and rock in tunnel construction and the effect on thestability of the surrounding rock. Through the analysis, research, get the followingconclusion:①Influence on the stability of surrounding rock under the different statediscussed in this paper through the tunnel excavation：Through calculation and analysis of the tunnel vault which is nearly horizontalcoal seam under the process of construction state model, obtained the law ofsurrounding rock mechanics under the construction condition, summarizes theconstruction state can effectively prevent the instability of surrounding rock in theconstruction process. As the model didn’t be inverted arch, so the model along withthe construction process of surrounding rock of tunnel of inverted arch bottom,accelerating the stability of surrounding rock was decreased and the inverted archapplied is necessary.②Influence on the stability of surrounding rock under the different distancebetween tunnel and nearly horizontal rock series：The nearly horizontal, distribution at the top of tunnel vault, with the increase ofdistance from the tunnel, has little impact to the stability of tunnel surrounding rockexcept the inverted arch Angle place; The nearly horizontal, distribution below thetunnel vault, as the distance increases with the tunnel, has little impact the stability oftunnel surrounding rock except the arch waist place; The nearly horizontal, distribution near the tunnel walls, with the increase of distance from the tunnel, haslittle impact on the stability of tunnel surrounding rock.③Influence on the stability of surrounding rock under the different thick ofnearly horizontal rock series：The nearly horizontal, distribution at the top of tunnel vault, with the increase ofits thickness, the impact to the stability of tunnel surrounding rock except the invertedarch Angle place has increase; The nearly horizontal, distribution below the tunnelvault, with the increase of its thickness, the impact the stability of tunnel surroundingrock increase except the arch waist place; The nearly horizontal, distribution near thetunnel walls, with the increase of its thickness, has little impact on the stability oftunnel surrounding rock but theoreticallydecrease.④Influence on the stability of surrounding rock at different location of nearlyhorizontal rock series：The calculation results of the analyzed of the stability in tunnel surrounding rockwith nearly horizontal rock series in different location show that: At the top of tunnelvault, it at the site of the biggest influence to surrounding rock stability; Below thetunnel vault, has smaller impact on the stability of surrounding rock than it at the topof tunnel vault. Near the tunnel walls, the impact on the stability of surrounding rock,basic can be ignored.Combined with the engineering example of Shi-tang tunnel, this paper based onthe numerical simulation of the different location and different thickness of nearlyhorizontal coal series and analyzed on the sensitivity of the surrounding rockmechanics parameters of tunnel excavation construction provide effective basis andthe suggestion for the tunnel design and construction. So for coal of weak rock tunnelexcavation methods are analyzed and the stability of surrounding rock has importantpractical significance and academic value, provide some useful reference for suchtunnel after excavation.