Strategies to Reduce Ground Settlement from Shallow Tunnel Excavation: A Case Study in China: Fid-Bau Portal

Strategies to Reduce Ground Settlement from Shallow Tunnel Excavation: A Case Study in China

Zhang, Limao / Wu, Xianguo / Liu, Huitao

This paper develops a holistic simulation-based approach to determining reasonable strategies to limit the magnitude of ground settlement in shallow tunnel excavation. Simulation models are built to investigate and analyze the impact of different response strategies on the development tunnel-induced movement. A real tunnel case with a shallow buried depth of 5–8 m in the Wuhan metro system in China is utilized to demonstrate the applicability of the developed approach. Results indicate that (1) the simulation technique can be used to model the complex tunnel-soil-ground interaction in a reliable manner and predict the tunnel-induced ground settlement given some grouting strategies are implemented; (2) the optimal control strategy to reduce the tunnel-induced ground settlement should first satisfy the requirement of safety consideration where the ground settlement should be controlled within an allowable range and should then satisfy the cost effective requirement; and (3) the continuous grouting strategy is more suitable to deal with the excessive settlement in case the thickness of covering soil layers is almost equal or less than the tunnel diameter because it can reduce the ground settlement by almost 50%, compared with the situation where no grouting strategies are implemented. The developed approach takes into account both the knowledge of domain experts and computer science techniques and can be used by practitioners in the industry as a decision tool to provide beneﬁts in the development of better alternatives and optimization.