Abstract
Effective measures are needed to strictly control soil displacement caused during the process of shield construction excavation for urban subway tunnels. When calculating the displacement of soil caused by loading or unloading, many previous analytical studies have assumed that the soil was a linear elastic body and ignored the viscosity of the soil. In this study, the Boltzmann viscoelastic model and the Mindlin basic solution were combined to consider the effects of the additional support pressures, the shield shell frictions, the grouting pressures, and the ground loss, and a three‐dimensional viscoelastic solution for soil displacement caused by shield tunneling was derived. According to the calculation results of an example, the analytical solution was able to consider the asynchronous construction of the left and right tunnels and the mutual influence of the double shield tunnel. The rationality of the approach proposed in this study was verified by comparing the theoretical solution with the measured settlement values. In addition, the influence of differences in the viscoelastic parameters (the viscosity coefficient, the shear modulus of the elastic element, and the shear modulus of the viscous element) and the geometric parameters (the distance from the excavation surface, the calculated depth, and tunnel spacing) on soil displacement is discussed. The calculation method in this study provides a theoretical basis for predicting the three‐dimensional soil deformation caused by shield tunneling, especially in soft clays.
Highlights
Due to the continuous deterioration of surface traffic conditions, many large and medium-sized cities have built underground transportation networks to ease pressure on surface traffic
Jin et al [4] proposed an approach to estimate three-dimensional ground displacements induced by shield tunneling using the Advances in Civil Engineering superposition method, and they considered the effects of ground loss, additional support pressures, shield shell frictions, and cutter head rotation during shield tunneling
Based on the Mindlin solution and the Boltzmann viscoelastic model, this study comprehensively considered the influence of the additional support pressures, the shield shell frictions, the grouting pressures, and the ground loss, and proposed a three-dimensional viscoelastic solution of the soil displacement caused by shield tunneling. e following conclusions were drawn: (1) e calculation model considered the nonsynchronous construction of a double-line tunnel and the mutual influence between the two tunnels
Summary
Due to the continuous deterioration of surface traffic conditions, many large and medium-sized cities have built underground transportation networks to ease pressure on surface traffic. Zhang et al [3] presented a closed-form analytical solution for predicting long- and short-term ground deformations and liner internal forces induced by tunneling in saturated soils in which shield excavation effects with and without air pressure are both considered. Erefore, the research regarding the three-dimensional viscoelastic analytical solution of shield tunneling is of great significance to accurately understand and predict the soil displacement and soil-structure interaction caused by construction. Is study combines the Boltzmann viscoelastic model and the Mindlin basic solution and deduces a three-dimensional viscoelastic solution of soil displacement caused by shield tunneling that considers the effects of the additional support pressures, the shield shell frictions, the grouting pressures, and the ground loss. The influence of differences in the viscoelastic parameters and geometric parameters on soil displacement is discussed. e calculation method proposed in this study provides a theoretical basis for predicting the three-dimensional soil deformation caused by shield tunneling
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