Analytical investigation for the circumferential behavior of the shield-driven tunnel adjacent to a braced excavation

The excavation adjacent to existing tunnels in close proximity becomes a common recurring problem in urban areas. Due to the presence of joints, both the longitudinal and circumferential flexural stiffness of the shield-driven tunnel are significantly reduced. However, most of the previous studies focus on longitudinal tunnel deformation features. In this study, a simplified method for evaluating the circumferential behavior of the shield-driven tunnel adjacent to a braced excavation is proposed. A continuous ring structure under plane strain condition is used to determine the circumferential behavior of segmental lining A typical tunnel cross section subjected to a series of circumferential loads is used to study circumferential behavior, including tunnel convergence and lining internal forces. Additionally, a parametric study is performed to develop a better understanding of the governing factors of tunnel behavior, including excavation-tunnel relative position and the soil condition.