Shield Excavation Analysis: Ground Settlement & Mechanical Responses in Complex Strata

This study delves into the effects of shield tunneling in complex coastal strata, focusing on how this construction method impacts surface settlement, the mechanical properties of adjacent rock, and the deformation of tunnel segments. It investigates the impact of shield construction on surface settlement, mechanical characteristics of nearby rock, and segment deformation in complex coastal strata susceptible to construction disturbances. Utilizing the Fuzhou Binhai express line as a case study, we developed a comprehensive numerical model using the ABAQUS finite element software. The model incorporates factors such as face force, grouting pressure, jack force, and cutterhead torque. Its accuracy is validated against field monitoring data from engineering projects. Simulations were conducted to analyze ground settlement and mechanical changes in adjacent rock and segments across five soil layers. The results indicate that disturbances are most significant near the excavation zone of the shield machine, with a prominent settlement trough forming and stabilizing around 2.0–3.0 D from the excavation. The excavation face compresses the soil, inducing lateral expansion. As grouting pressure decreases, the segment experiences upward buoyancy. In mixed strata, softer layers witness increased cutting, intensifying disturbances but reducing segment floatation. These findings offer valuable insights for predicting settlements, ensuring segment and rock safety, and optimizing tunneling parameters. © 2024 Tech Science Press. All rights reserved.