Research On The Stability For The Structure Of Rock And Support In The Bi-Arch Tunnel

Based on the Yinjiayan bi-arch tunnel engineering of the Hurong national highway trunk-line in Hubei Province Yichang (the Changjiang Rive bridge) to Changyan (Baishiping) highway, the thesis primarily discourses upon the numerical simulation analysis of the stability of the excavating and supporting during the bi-arch tunnel construction in the surrounding rock by the finite element method(FEM) calculation , adopting the elasto-plastic and visco-elasticity theory and the method of the time-state of the tunnel information.Combining the study characteristic and the current construction method of the bi-arch tunnel in domastic and aboard, the paper deeply study the middle heading construction method and the benching tunneling construction method. Firstly by the dynamical FEM (GeoFBA-V3.0) calculation about the above two construction method, the paper analyses the stress field and displacement field of the surrounding rock and the axial force and bending moment of the steel framework, specially analyses the most important member the central wall and obtains the stress pattern during the different construction working procedure. After comparing the two methods, the Paper considers the benching tunneling method is better. At the same time, based on visco-elastic theory on interaction of surrounding rock of the tunnel with support, the transformation law of the stress and displacement with time of the bolt-shotcrete support is discussed. Calculated the thickness of the shotcrete with the surrounding rock and compared with the design, achieve a satisfying result. Finally, the thesis analyses the time-state curve of the axial force and bending moment of the steel framework and the axial force of the anchor bolt. The analysis result, are compared with the results of the FEM calculation. Through the FEM calculation and the analyzing data of the field, the result is that the central wall mainly endures the vertical Pressure from the structure transferring and its bending moment is relatively less and its position of the maximum value of the bending moment locates in the joint between the central wall and the steel framework.In a word, precision of the numerical simulation analysis of the stability of the excavating and supporting during the bi-arch tunnel construction is credible and its prospect is refulgent, if the defect of the numerical simulationanalysis is perfected stage by stage, strengthening on collecting and analyzing the information about displacement, persisting in the principia of theory and practice, and improving the cognition of rock dynamo. These results can have the guiding significance to the design and construction of the similar tunnel engineering.This project is a scientific and technological project of traffic of Hubei (03-66-3/4).