Improved Theoretical Solutions for Estimating the Tunnel Response Induced by Overlying Excavation

As a result of China's urbanization, it has been a common phenomenon that adjacent deep excavations were constructed near underground structures, which can have a series of detrimental effects on existing tunnels. Thus, it is crucial to assess the tunnel response induced by the overlying excavation, with the aim of maintaining the safety and serviceability of operating tunnels. The shield tunnel is idealized as an infinite beam lying upon a three parameter Kerr-model and the vertical force equilibrium equation of the tunnel element is established. Then, a theoretical solution is derived for capturing the soil-tunnel interaction. To prove the accuracy of the proposed method, the calculation results are compared with field measurements, along with the data of finite element studies. Thereafter, a parametric analysis will be conducted to assess some characteristic factors for tunnel responses caused by overlying excavations, such as tunnel-excavation horizontal distance, tunnel bending stiffness, and the buried depth of the tunnel. The results indicate that the increase in the bending stiffness and the buried depth of tunnel, as well as the tunnel-excavation horizontal distance, will significantly alleviate the tunnel deformation. However, the inner force will be increased when increasing the tunnel bending stiffness.