Stability Analysis Of Closely Spaced Tunnels Surrounded By Broken Rocks

Due to complicated topographical and geological conditions, the constructions of high-grade highways unavoidably meet with lots of tunnel projects. Limited to special geological and topographical conditions, the space of tunnels can't satisfy the requests of technical codes. Considering the technology and economy aspects, small spacing tunnels are usually constructed when the routine are not changed. The entrance or exit of the tunnel will go through the landslide sometimes due to some objective factors. The stability of surrounding rocks is worth researching in such conditions.Based on the Poshijie II highway tunnel project, conducted by the NATM, the three-dimensional numerical model is built by using FLAC3D. The small space section is simulated and the stability of the surrounding rocks is analyzed. The changing regularity of stress and displacement of the surrounding rocks, the rule of spatial effects between the forward hole and back hole and the reasonable distance between the two tunnels surrounded by broken rocks are obtained. The comparison between the numerical simulation results and the actual control monitoring data shows that the results of numerical analysis are reasonable and feasible. In addition, according to the analysis of the simulation of the tunnel through the landslide, the vertical and lateral displacement as well as the changing regularity of the surrounding rocks and changing regularity of the stress of tunnel lining affected by landslide in tunnel construction are obtained, the interaction between the landslide and tunnel excavation are discussed, and the stability of surrounding rocks are further studied during the tunnel excavation. The thesis has the guiding sense to the resemble tunnel engineering in the future.