Research On The Influence Of The Shallow-buried Tunnel Excavation On The Adjacent Constructions

At present, more and more city expressways, intercity rails and subways.etc being constructing, an increasing number of shallow-buried tunnels need to be excavated. Usually, these shallow-buried tunnel tunnels tend to pass through some of the residential intensive areas, so that the impact on the adjacent constructions on the surface by the shallow-buried tunnel excavation was inevitable. Therefore, analyses of the law that the influence of the shallow-buried tunnel excavation on the earth’s surface deformation and adjacent constructions deformation, analyses and forecasting of the adjacent constructions deformation may occurs in different conditions, on these basis, how to take effective measures to reduce the deformation of the surface and adjacent constructions have been an important issue that has to be addressed in the urban underground construction projects.Based on the systematic access to the relevant research results at home and abroad and discussion on the different research methods, this paper takes an shallow-buried two-lane railway tunnel, that across residential intensive areas, as an example, adopted the numerical method to analyze the law that the shallow-buried tunnel excavation impact on the adjacent buildings deformation under different factors.Obtained the influence of shallow-buried tunnel excavation on the adjacent constructions under the conditions of different spatial relationship between the construction and the tunnel (i.e. the distance between the centerlines of construction and the tunnel, tunnel depth, the angle between the construction long axis with the tunnel centerline), different upper load, different foundation thickness and different excavation methods (Three-step method, CRD method and Double-side heading method). This paper analyzed and summarized the variations in four aspects of earth surface subsidence, the foundation settlement, the foundation deflection rate and the foundation twist rate. The main contents are as follows.Systematically analyzed the research result at home and abroad on the surface deformation caused by shallow-buried tunnel construction and its impact on the adjacent buildings. Especially focuses on the mechanism of the adjacent constructions damage caused by the tunnel excavation and the failure mode of the constructions.Based on the summaries of he relevant research results at home and abroad, the assess methods and the main index of the impact on adjacent constructions of the shallow-buried tunnel construction.Numerical analysis method was adopted to establish the models under different conditions of spatial relationships between the construction and the tunnel (i.e.the distance between the centerlines of construction and the tunnel, tunnel depth, the angle between the construction long axis with the tunnel centerline), by the deformation analysis of the surface and the constructions, draws the influence of tunnel construction on the adjacent constructions under different spatial relationships. Numerical analysis method was adopted to establish the models under different conditions of upper loads and foundation thickness, by the deformation analysis of the surface and the constructions, draws the influence of tunnel construction on the adjacent constructions with different upper load and foundation thickness.Numerical analysis method was adopted to establish the models that use different excavation methods, by the deformation analysis of the surface and the constructions, draws the influence of tunnel construction on the adjacent constructions when different excavation methods was applied.