Abstract
Nowadays, a huge number of shield-driven tunnels with noncircular cross sections are constructed in urban areas all around the world. However, the ground displacements associated with tunneling still form a difficult issue, especially for noncircular tunnels. In this study, an analytical solution is derived to estimate the ground displacements induced by the deformations of shallow noncircular tunnels in soft ground. First, a solution for the stresses and displacements around a deep tunnel in a full plane is formulated by imposing a specified convergence pattern over the cavity boundary. Subsequently, this solution is validated using finite element simulations in a case study of an elliptical tunnel with four different convergence patterns. Afterward, the solution in the full plane is extended to a half plane using the virtual image technique to estimate the ground displacements around shallow tunnels. The solution is also validated using finite element simulations.
Highlights
In the last twenty years, a variety of special-shaped shields have been developed to build tunnels with many different shapes and cross sections [1,2,3,4,5,6,7]
Compared with the most widely used circular tunnels, noncircular tunnels are believed to have the advantage of making full use of excavated space [8]. us, they have been more and more frequently employed in urban areas for transportation development
During the construction of shallow tunnels in soft ground, one critical concern is the ground movements associated with tunneling
Summary
Qiongfang Zhang ,1,2 Kang Cheng ,3,4 Cungang Lin ,5 Yadong Lou ,6 Panpan Guo ,4 and Xiaolu Gan 4. The ground displacements associated with tunneling still form a difficult issue, especially for noncircular tunnels. An analytical solution is derived to estimate the ground displacements induced by the deformations of shallow noncircular tunnels in soft ground. A solution for the stresses and displacements around a deep tunnel in a full plane is formulated by imposing a specified convergence pattern over the cavity boundary. This solution is validated using finite element simulations in a case study of an elliptical tunnel with four different convergence patterns. The solution in the full plane is extended to a half plane using the virtual image technique to estimate the ground displacements around shallow tunnels. The solution in the full plane is extended to a half plane using the virtual image technique to estimate the ground displacements around shallow tunnels. e solution is validated using finite element simulations
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