2D numerical study of wave and current-induced oscillatory non-cohesive soil liquefaction around a partially buried pipeline in a trench

Abstract

This paper proposes a two-dimensional (2D) coupled model for wave and currentseabed-pipeline interactions to examine oscillatory non-cohesive soil liquefaction around a partially buried pipeline in a trench. Unlike previous studies, two new features are included in this model: (1) wave-current interactions around the pipeline; and (2) fully coupled processes for the wave and current-seabed-pipeline system. In this study, the Reynolds Averaged Navier-Stokes (RANS) equations are applied to simulate the flow field around the pipeline, and Biot's poro-elastic theory for porous media is imposed to govern the soil response due to the wave-current loading. After being validated using data available in the literature, the 2D model is used to investigate the effects of the current velocity, the soil properties, and the wave characteristics on oscillatory non-cohesive soil liquefaction. Using the model, a function for the critical backfill thickness and the wave steepness under various flow and soil conditions is proposed to facilitate engineering practice.

Two-Dimensional Numerical Study of Seabed Response around a Buried Pipeline under Wave and Current Loading

“…In this study, the length of the computational domain (l) is set to be three times the wavelength to ignore the influence of lateral boundaries. [25] and three-dimensional [26] numerical simulation to study the wave-current induced soil liquefaction around the buried pipeline. However, in their research, only the oscillatory soil response under a wave and current loading have been determined.…”

“…e max − e e max − e min (25) As seen in Equation 17, when there is a change in the relative density of the soil, both the empirical coefficient α r and β r in the source term f (x, z, t) varies, which eventually leads to different values of residual pore pressure. Figure 6 shows the generation of oscillatory and residual pore pressure due to the influence of various relative density (D r = 0.2, 0.3 and 0.5) over a certain period at point x = 50 m and z = -10 m. In this section, the soil permeability (k) and shear modulus (G) are set as 1.0 × 10 −4 m/s and 5.0 × 10 6 N/m 2 respectively while other parameters remain unchanged as shown in Table 1.…”

A Numerical Approach to Determine Wave (Current)-Induced Residual Responses in a Layered Seabed

“…The advantage of this approach is simple and identical to previous closed-form analytical solu-tions for fine sand, but significant differences were found for coarse sand (Hsu and Jeng, 1994). Based on the quasi-static (QS) model, some numerical models are established to study the soil response around the pipelines (Duan et al, 2017b) and breakwaters (Liao, Tong, and Chen, 2018;.…”

Wave-Induced Seabed Response around a Dumbbell Cofferdam in Non-Homogeneous Anisotropic Seabed

“…Field observations of some project cases have shown that wave loads do not usually cause direct damage to the strength or stiffness of an offshore structure but they often lead to the seabed liquefaction of the region that surrounds the offshore structure and subsequently result in the partial or total loss of bearing capacity [5][6][7][8]. Pile foundations, pipelines and breakwaters have received great attention in the study of wave-seabed-structure interactions [9][10][11], whereas cofferdams have been neglected in such investigations. Therefore, the study of the wave-induced seabed response around cofferdams is of great significance to the safety control during civil engineering construction.…”