The Design, Construction Technologies And Structural Optimization Of Double-arch Tunnel Under Unsymmetrical Pressure

As an innovative tunneling structure, double-arch tunnel has many advantages, such as high flexibility to different landform condition, smooth line shape, less occupation of space, large span, structural integrity, and relatively low integrated cost. Along with small-distance tunnel, double-arch tunnel is one of the feasible solutions for tunnel construction in China at present. However, because of its own characteristics, such as shallow depth of burial, unsymmetrical pressure, small height-to-span ratio, complex geological conditions and structural stress, the application and study of double-arch tunnel under unsymmetrical pressure are still at a preliminarily stage, and this is especially true for the systematic study on the structural design and the mechanism of the mechanical response during construction, which cause the lack of guideline for design and construction in engineering practice, and a great lag between the practical application and the theoretical research of optimum structural design. Therefore, it is very important to analyze the design, construction technologies and structural optimization of double-arch tunnel under unsymmetrical pressure combining with the practical engineering project in order to consummate the design and construction of double-arch tunnel.The thesis depends on the research project "some key technologies research during construction of tunnels", focusing on the research in the first tunnel in BaiYangChong of JingWuHuang(Chang) highway. On the base of analysis of causes for unsymmetrical pressure of double-arch tunnel, the critical design technologies of double-arch tunnel under unsymmetrical pressure are summed up.Then, the selection of construction methods of double-arch tunnel under unsymmetrical pressure is setted forth by analysis and comparison. At the same time, in order to understand the effects of the construction procedures on the mechanical response of double-arch tunnels under unsymmetrical pressure, the effects of the critical construction technologies during the construction of the middle wall and the middle heading on the stress and deformation of the structures are analyzed using the...