Back Analysis of Ground Pressure for the Deep‐Buried Shield Tunnel in Clay: A Case Study

Abstract With underground space development, underground structures' burial depth is increasing. Determining the ground load acting on the lining is key to the structural analysis and design of shield tunnels, especially for these deep‐buried shield tunnels. To investigate the ground pressure acting on the deep‐buried shield tunnel, this study presents a back analysis of ground pressure based on on‐site monitoring. The on‐site monitoring has been conducted to obtain the internal forces of segmental lining with a buried depth of 67.5m for Longquan shield tunnel. Based on measured structural internal forces, the Levenberg‐Marquardt method (LM method) is introduced into the back analysis of ground pressure during the construction and stable stages. Through back analysis, the applicability of the LM method in the back analysis is discussed, and the characteristics of the earth pressure acting on the structure during the construction period and the stable stage are analyzed. Results indicate that the LM method has good accuracy and computational efficiency in the back analysis of ground pressure. The earth pressure shows significant time‐dependent characteristics and increases uniformly around the tunnel perimeter with time. For shield tunnels buried deep in clay, ground stress transfer exists due to the excavation, and the soil arching effect helps reduce the earth pressure on the tunnel structure.