The Numerical Analysis On Behaviors Of The Shallow Tunnels And Settlements Of Buildings In The Construction Process

With the development of subway tunnel, more attention has been attracted by the related geotechnical engineering problems. The settlement of ground surface due to the construction of tunnel is the main cause which results in the damage of the appearance and the function of buildings on the groud surface. In general, the buildings on ground surface are not considered in the design of a subway tunnel, and the main measurement for protecting buildings is to control the settlement of ground surface in the construction process. The practical method in construction is to set a upper limit of settlement for controlling the construction or modifying the primary design. This method ignores the specific types of buildings on the groud surface and the interaction between buildings on the groud surface and a tunnel, so those strengthening measures are not very reliable.In this paper, FLAC^3D (Three Dimensional Fast Lagrangian Analysis of Continua) is used to analyze the behaviors of the shallow tunnel and settlement of the buildings on the groud surface in the construction process. The effects of different factors are considered in the analysis, and some academic instruction for tunnel construction are presented.Firstly, the theory of FLAC^3D is described briefly. Then, the methods of shallow tunnel construction (STCM), the characteristics and suitable condition of STCM, and the construction technology of STCM are introduced briefly.Secondly, the numerical model for shallow tunnel is established by FLAC^3D and the effects of different factors on the behaviors of shallow tunnel construction and the ground surface settlement are investigated. The focuses of study are on the influences of the character of wall rock, the method of tunnel excavation and reinforcement, the length of excavation, the buried depth, the diameter of excavation and the condition of stratum on the stability of wall rock.Finally, the interaction between the shallow tunnel and buildings on the groud surface is researched. Considering the influence of the distance between buildings on the groud surface and the tunnel, the buried depth, the base of buildings on the groud surface and the ubiety of the base and the tunnel, stress distribution, distortion response of the tunnel and base settlements are analyzed. The influnences of many factors on the interaction between a tunnel and buildings are discussed.