Application of Numerical Simulation Technology in New Intelligent Reinforcing Method of Shield Tunnel End in Seaside Environment

Abstract

The instability of the soil at the shield end is an important safety hazard in shield tunnel construction. In loose and weak strata, the risk of instability and damage is higher, and the loss is greater. In this paper, the instability and failure of the end soil in loose and weak strata are studied. To ensure the smooth start and arrival of the shield and avoid engineering accidents such as end soil instability, surface subsidence, landslides, etc., during the construction process, this paper summarizes the commonly used reinforcement technology and characteristics of the shield in and out of the tunnel. Through numerical simulation, the influence of the thickness of the added solid on the formation and diaphragm wall is analyzed. It is found that the reinforcement effect increases with the increase in thickness of the added solid, but the change rate becomes smaller and smaller. The indoor triaxial test is used to find out the physical and mechanical properties of loose sand and soft clay. The biaxial compression numerical model is built with PFC2D (Particle Flow Code 2D), and the wall constraint type is improved. With the help of the PFC biaxial test, the influence of model parameters on the macroscopic properties of the simulated material was analyzed. The research has certain reference values for the actual construction of the project.

Numerical Simulation of Construction Disturbances during Bidirectional Advancement of Undersea Large-Diameter Dual-Line Shield Tunneling

“…It was shown that the vertical displacement of the tunnels was significantly affected by the soil properties. Zeng et al [23] focused on the endings of shield tunnels and investigated the instability and damage of end soils in loose and weak strata and, using numerical simulation, the authors found that the reinforcement effect increases with the increase in thickness of the added solid, but the change rate becomes smaller and smaller. To investigate the shutdown problem of shield tunneling machines, Hasanpour et al [24] utilized finite-difference software to simulate the excavation process in unfavorable strata, and the results help to realistically assess the effect of unfavorable geological conditions on shield blockage.…”