Analysis of Ground Settlement Caused by Double-line TBM Tunnelling under Existing Building

Abstract

\n TBM tunnelling is less used in the subway construction in prosperous city due to the limitation of the engineering geological conditions. The studies on the influence of the TBM construction on the existing buildings are also limited. Therefore, based on the engineering case of tunnel crossing existing building in the section of Haiboqiao\u2009~\u2009Xiaocunzhuang station of Qingdao Metro Line 1, the numerical model that simulates the construction process of TBM tunnelling in slightly weathered granite layer is established by three-dimensional finite difference software FLAC3D to analyze the influence of TBM tunneling on ground settlement. The comparisons of ground deformations obtained from FLAC3D and field monitoring in different construction stages of double-line tunnel have been made firstly to validate the numerical model. Then the ground settlement characteristics, differential settlement and the stress distribution of the existing building and the stress of segment structure have been analyzed. Ground settlement groove along the transverse and vertical sections occurs near the building and tunnels, and the settlement becomes smaller with the farther distance from them. The settlement curve on the cross section changes dynamically and is approximately V-shaped, and its width is about 5\u2009~\u20096 times diameter of the tunnel. For the same cross section, the range of the settlement groove after tunnelling right line increases obviously compared with that after tunnelling left line (construction first), the settlement values also increase, and the symmetrical axis of the settlement curve is shifted to the right. This paper can provide important practical reference for relative construction engineering.