Study On Optimizing The Method About Construction Of Space Reverse Cross Tunnel

Space torsion cross tunnel is a special tunnel structure,two or more newly constructed small spacing tunnel turned and twisted in the space,their relative position of the space changes along the tunnel axis,stress and deformation of surrounding rock and supporting structure are changing with the change of relative space position of two tunnels.This article is base on the tunnel construction aimed at the section 2,first phase civil engineering of Chongqing metro Line 4 between Xiazibian Station to Jinshan Station,we drew a conclusion of the best tunnel construction scheme and summarized the stress and deformation law by doing mechanical analysis and finite element study.The main research contents and results are as follows:① We provided a brief introduction to the basic theory of space torsion cross tunnels,summarized the partition criterion of the mutual influence torsion cross tunnels,meanwhile,this article thesis describes the mechanic effects of single tunnel excavation and stress redistribution caused by excavation of adjacent cavern under the relative position of typical space.② We drew the follow conclusions by doing three dimensional construction simulation for practical engineering,studied the deformation and mechanic response Surrounding rock and supporting structure of two typical cross section of space torsion cross tunnel by making comparison of different excavation sequence,different footage of excavation, and different support surface spacing.1) This space reverse cross tunnel under two kinds of excavation sequence of numerical simulation for the process of excavation, two different excavation sequence surrounding rock and supporting structure deformation, the mechanical response characteristics, and to determine a reasonable excavation sequence.2) This space reverse cross tunnel using a numerical simulation of the excavation of the six may get two tunnel surrounding rock and supporting structure deformation, the mechanical response characteristics changing with the excavation, and determined the reasonable excavation.3) Reverse cross to the space using four different tunnel excavation surface spacing for numerical simulation of the two deformation of tunnel surrounding rock and supporting structure, the mechanical response characteristics with the change rule of distance constraints, two constraints of tunnel excavation and determine a reasonable distance.