Three-Dimensional Simulation of Twin Tunnels in the Overcrossing Section of the Hangzhou Metro Line

This study addresses the challenges associated with urban tunnel construction in China’s rapidly expanding cities, emphasizing the EPB-TBM method. While the EPB-TBM offers high efficiency and minimal disruption, concerns arise when implementing it in densely populated urban spaces with pre-existing structures. The study aims to provide a numerical simulation of EPB-TBM using an advanced constitutive model to closely align with real monitoring data, highlighting the need for effective geotechnical protective measures. Without proper safeguards, the risk of damage remains significant, especially for aging tunnels. This study presents a scenario wherein twin tunnels in close proximity are excavated above pre-existing tunnels within a soft soil stratum. The research method includes numerical simulations and in situ monitoring to analyze deformation characteristics. Key findings reveal uplift in the first overcrossing and a shift in symmetry centers in the second, offering valuable insights for optimal protection and prompt assessment methods for existing tunnels during urban tunnel expansion.