The Study On Stability Of Folder Rock And Size Optimization Of Tunnel With Small Spacing In GradeⅤ

China is a vast territory country, which is most of the main landforms in mountain hills and extremely complicated geological conditions.Therefor in advanced highway, railway and subway construction, the tunnel will adopt a large number of tunnel projects, and it is confined to such conditions as topographical factors, the overall line of linear. The settlement has to construct double-hole or porous tunnels at insufficient space. Under these circumstances, the main way is used of double-arch tunnel, the tunnel with small spacing and other special structure at present, For one thing, double-arch tunnel construction technology is rather complex, longer duration, and the other is existence of the water proof, in wall cracks and other quality problems, so the application structure has been widely questioned. For this reason, small spacing tunnels can solve the problem fairly good, either in the way of two-hole cable tunnel or overcoming arch tunnel technology, duration, cost and quality issues effectively, and it has been widely used in the domestic mountain road tunnel construction.Through the research of small spacing tunnel monitor at the scene, we find that it should focus on ensuring construction and transportation according to the stability of rock in the folder, the other problem, the rock of tunnel is influnced by thickness of the folder rock , and there a phenomenon which exist in the rock folder is stress concentration, it is prone to cracking and block out; After tunnel excavation and support, the creep deformation of rock is a long time; therefore, rock reinforcement in the folder rock is related to the stability of the entire tunnel, the same it is key to success for tunnel construction.In this paper, I empoly three-dimensional finite difference method based on project for the tunnel with small spacing and set off study on such issues: rock stress, displacement, strain and rock the stability of the folder,discuss the project of optimal method, a reasonable distance and reasonable construction of space. Undering the analysis by comparing the results of different working conditions which found in the tunnel with small spacing , the method selection should take into account the way of rock in the temporary folder reinforced measures to ensure the stability of rock; in the field of studies on reasonable tunnel distance, we have found that the stability of small spacing tunnel by the size of the impact of distance is very obvious, as the distance changes, the indicators surrounding changes in several stages, through the different stages of the specific circumstances of projects, we selected the reasonable distance based on the net distance; because of its specificity, in the construction process of small distance tunnel structure should be considered in two-hole between the working face of the rock stability, by the three-dimensional numerical simulation study we found that the ultimate value impacted on the spacing of the tunnel construction of the indicators is tiny, but different construction on the surrounding space, especially in the construction of folders in each cycle of rock is influenced obviously, and finally the calculation results and duration of different distance is required the reasonable distance based on the project.This paper summarizes the conculation results by finite different method and the law of rock changes under the tunnel construction process, according to these results, focused on the temporary tunnel design distance and construction method, we take an optimizing adjustment.