Study Of Ground Surface Settlement During Overlapped Tunnel Excavation In Qingdao City

As the requirements of Metro line's setting, sometimes, there is overlapped tunnel in building Metro engineering. The most concerning of people is the influence on circumstance of city by excavation of tunnel. Namely, it is the influence on the use of pipe under ground, foundation of building and traffic. So, it is very important for the secure of design and construction to forecast the settlement of ground surface induced by the excavation of the overlapped tunnel exactly.Firstly, This paper simply introduces the style of the overlapped tunnel at home and abroad, and model of FLAC3D, then, refers the project of the overlapped tunnel in the ZhenHua road period of Qingdao Metro engineering, through three-dimensional FEM numerical simulation, researches the ground surface settlement and influence on the upper construction in fully efflorescent terrene by New Austrian Tunneling Method. Looking upon rock and soil as stochastic medium, using of theory of superimposition, considering of the final settlement of ground surface, this paper advances the amendatory Peck formula at the base of the widely used Peck formula for forecast of settlement of ground surface. Compared the settlement of ground surface according to the amendatory formula with the settlement of ground surface according to FLAC3D, it is found that both of them is basically identical. So, the amendatory formula can be used to forecast the settlement of the ground surface of the project of the overlapped tunnel in the ZhenHua road period of Qingdao Metro engineering. In order to achieve the optimized tunneling approach, first, tunneling methods, tunneling procedures, shift length, bench length are optimized; On the basis of these results, the optimized tunneling scheme is achieved. Considering the load of construction on the ground surface, the change of the upper construction's internal force during the course of overlapped tunnel's excavation are studied. Considering the relative location between the overlapped tunnel and the upper construction and utilizing the results of the overlapped tunnel's excavation - the infundibular face on the ground surface, the security of the upper construction is analyzed. The conclusion is made that the upper construction above the overlapped tunnel is secure.