Abstract
Water inrush from the excavation face often occurs in the current shield construction of metro tunnels. In this study, the discontinuity of shield tunnel lining and the interaction between the tunnel segments, the grouting layer, and the surrounding rock are considered. Based on the 3D nonlinear contact theory, a hybrid model of the shield tunnel is constructed. Considering the fluid-solid coupling effect of water and soil, the influences of different water head differences on the mechanical performance and deformation of segments and joints in the shield tunnel are studied. The water gushing from the excavation face leads to vertical convergence of the cross-sectional area of the shield tunnel, and joint opening and dislocation result in sharp decrease of the waterproof capacity of joints. Meanwhile, the stress in the vicinity of segment joints increases sharply, and local cracks occur in the segment lining. The axial force, shear force, and bending moment in the joint bolt are also significantly increased. Based on the current metro standard and the computational results in this study, an emergency control criterion is put forward by means of controlling the discharge of water: the water head difference over the excavation face is required less than 4.6 M.
Highlights
Elon Musk, the CEO of Tesla, announced lately that they will excavate underground tunnels to solve the problem of ground tra c congestion, and they started a company named Boring to develop a new type of shield construction machine for this purpose
When water inrush occurs in the process of shield construction of the metro tunnel, the water head di erence over the excavation face varies
With the aim of studying the inuences of continuous water inrush from the excavation face on the mechanical properties and deformation of segment joints, a multiscale hybrid model of the excavation face in a shield tunnel is constructed based on the three-dimensional nonlinear contact theory and applied to simulate a section of Xiaodongmen to the Wuchang station (XWS). e results of this study may provide reference for the engineering practice of shield tunneling. e following conclusions are drawn: (1) e vertical convergence of the shield tunnel mainly re ects the overall deformation of the existing tunnel during the continuous change of water in ow at the excavation face
Summary
Elon Musk, the CEO of Tesla, announced lately that they will excavate underground tunnels to solve the problem of ground tra c congestion, and they started a company named Boring to develop a new type of shield construction machine for this purpose. Few dealt with or considered the in uence of water inrush from the excavation surface of the shield tunnel (under drained condition) on segment joints when the excavation face has not become unstable and the ground surface has no large subsidence. Erefore, in studying the in uence of water inrush from the excavation face on the segments of the shield tunnel, the variations of the stress and deformation in the vicinity of segment joints should be taken into account. Is study takes as an example the water inrush from the excavation surface occurred during the shield construction in a section of railway from the Xiaodongmen station of Wuhan subway line 7 to the Wuchang station (Figure 1), to investigate the stress and deformation of metro tunnel segment joints when large amount of water gushes from the excavation face.
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