Deformation Analysis Of Surrounding Rock For Shallow And Large-section Tunnel In Loess Area

As a result of the especial property of the loess, the force deformation characteristics of tunnel which constructed in the loess region is more complicated compared with conventional tunnel. Large cross-section of tunnel often encounter a number of difficulties and problems in the loess region, such as collapse due to its large area and unfavorable conditions of surrounding rocks. It is evident that the degree of the difficulty of the tunnel construction is increasing sharply when the tunnel is shallow burial. To research on the deformation characteristics of shallow and large cross-section tunnel and analyze the deformation disciplinarian of the surrounding rock and supporting structure under the condition which effected by different factors, 3-D models which used in the tunnel construction was formulated.Combined with the field monitoring measurement, the tunnel construction was analyzed in this paper.The background of this article is Ru Yi tunnel which is located in He Yang city of Shan Xi province. Based on the geological condition and tunnel design size, firstly,using finite element software establish three-dimensional numerical calculation model against the test section from DK75+60 to DK75+95 to simulate the Ru Yi tunnel construction which was used three-bench seven-step excavation method. Analyzed the state of stress and strain of the surrounding rock and supporting structure caused by excavation of tunnel. According to the synthesis of the results, three-bench seven-step excavation method is a practicable excavation method for Ru Yi tunnel.Then, the monitoring measurement data was analyzed using regression analysis.Comparative analysis was done among the regression analysis results, the real-data and simulation results. Summed up simulation results can reflect the trend of the surrounding rock deformation. As the basis of judging the stability of the surrounding rock, the real-data is reliable.Finally, analyzed the deformation disciplinarian of the surrounding rock and supporting structure by numerical simulation the model with different conditions,such as using anchor whether or not, the excavation length of 1m, 2m, 3m of the invert arch one time and the length of 1m, 2m, 3m of the tunnel excavation. The influnence of the surrounding rock and supporting structure deformation caused by the anchor,the length of the invert arch excavation and the tunnel excavation has been analyzed during Ru Yi tunnel construction.