Effects of siltation and desiltation on the wave-induced stability of foundation trench of immersed tunnel

The evaluation of stability for the submarine artificial slope is important in the construction of offshore structures such as immersed tunnels and embedded pipelines. The siltation in marine dynamic environment is common, inevitable, but difficult to deal with. Cohesive sediment, or mud, is encountered in most water bodies throughout the world, and thus siltation inevitably occurs in the stage of underwater excavation for the offshore structure foundations. To this end, based on the temporal and spatial variations law of siltation observed from the trial trench in-situ test of Shenzhen-Zhongshan Link in China, a numerical study is carried out on the influences of siltation and desiltation on the stability of foundation trench slope under wave action. The waves are simulated by the Reynolds-Averaged Navier-Stokes (RANS) equations and then applied on the surface of seabed and trench slope. The pore pressure induced by the wave action is obtained by Darcy's law. The seabed is characterized by Mohr-Coulomb constitutive model and the factor of stability (FOS) of the slope is calculated using the strength reduction method. Three failure modes are assumed to analyze the stability of trench slope and to determine the most unstable mode. A sensitivity analysis is conducted on various key factors affecting the whole stability of the trench slope after siltation or desiltation, which is valuable for practical engineering design.

Automated summary

This study analyzes the stability of trench slope using numerical simulation and observational data. The influences of siltation and desiltation on stability are considered, and key factors are determined through sensitivity analysis. The research results are of great significance for practical engineering design.