Study On Construction Mechanical Behaviors Of The Complicated Urban Muliti-Tunnels Engineering

In recent years, as accelerating the steps of China's Urbanization, the transport infrastructure in city are developed further, there leads to a lot of engineering phenomenal that the new line would be built closed to the existing line, Therefore urban cross-over engineering has come forth. Furthermore, the scale of the engineering quantity is getting larger, the distance between two lines is becoming shorter and the interrelationship is more and more complicated. This phenomenon shall create the complex relationship due to the neighborhood between the new construction and the existing one. As a consequence, there are a lot of negative effects on the existing constructions. The larger of the scale of the construction, the more situations will occur. For instance, a new tunnel just is sideward another newly-built tunnel, and two or more tunnels are built at the same time, and also several subsections of a large crossing section are dug simultaneity.The paper spreads the correlation research out to the large cross section tunnel, the small spacing tunnel and the overlapping tunnel that has often appeared in the urban cross-over engineering, based on the reality tunnel projects, which called "Wan Shi Shan Tunnel" in "The First Project of Xiamen Airport" .and take the "Jin Kang Tunnel" in "Chang He Dam Waterpower Station" crossing-highway project as the background, the correlation study is developed in the grades crossing tunnel that has often appeared in the urban cross-over engineering in city too. In addition, this paper will use the analysis methods which named "Two and Three Dimension Finite Element Numeric" to study on the on the large cross section tunnel, the small spacing tunnel and the overlapping tunnel. Moreover, the research results of this paper apply directly in the actual project; it also has the guiding sense to the similar project, and provides certain reference for the correlation standard formulation.Firstly, through the investigation and the simulation method, the paper draws the conclusion of what are the main factors effecting the stability of the large cross section tunnel and its key construction technology.Next,through the finite element numeric analysis, study on the basic problem of non-symmetry small spacing tunnel, and discuss its standard of the classification.Finally,analyze the deformation and stress characteristic of the grade crossing tunnel and the grade separation tunnel by the finite element simulation in the construction course.