Response of a Porous Seabed around an Immersed Tunnel under Wave Loading: Meshfree Model

Abstract

Seabed instability surrounding an immersed tunnel is a vital engineering issue regarding the design and maintenance for submarine tunnel projects. In this study, a numerical model based on the local radial basis function collocation method (LRBFCM) is developed to evaluate the seabed behaviour in a marine environment, in which the seabed is treated as the porous medium and governed by Biot's "u − p" approximation. As for the flow field above the seabed, the VARANS equations are used to simulate the fluid motion and properties. The present model is validated with analytical solutions and experimental data which show a good capacity of the integrated model. Both wave and current loading are considered in this study. Parametric studies are carried out to investigate the effects of wave characteristics and soil properties. Based on the numerical results, the maximum liquefaction depth around the immersed tunnel could be deeper under the wave loading with long wave period (T) and large wave height (H). Moreover, a seabed with lower permeability (K s ) and degree of saturation (S r ) is more likely to be liquefied.

A non-Darcy flow model for a non-cohesive seabed involving wave-induced instantaneous liquefaction

“…The phenomenon of the fluid-seabed interactions has been analytically investigated under various conditions without a structure (Yamamoto et al, 1978;Madsen, 1978;Hsu and Jeng, 1994;Zhang et al, 2013). When a structure is considered, the complicated boundary conditions make the numerical analyses indispensable, such as submarine pipelines (Jeng and Lin, 1999;Gao et al, 2003;Zhao et al, 2014;Zhao and Jeng, 2016;Lin et al, 2016;Duan et al, 2017;Li et al, 2019;Liang et al, 2020;Liang and Jeng, 2021), breakwaters (Jeng et al, 2013;Zhang et al, 2018a;Celli et al, 2019), coastal slopes (Young et al, 2009), offshore wind turbine foundations (Chang and Jeng, 2014;Qi and Gao, 2014;Sui et al, 2016;Lin et al, 2017;Zhao et al, 2017;Li et al, 2018) and immersed tunnels (Han et al, 2019;Chen et al, 2021) etc. The structure-seabed interactions may introduce additional complexities, e.g.…”

New Advances in Marine Engineering Geology

“…Han et al [4] investigate the flow field dynamics and corresponding response of a porous seabed around an immersed tunnel under wave loading combined current with various velocities. They developed a 2D numerical model, which is composed of two sub-models: The flow model with OpenFOAM and the seabed model with a Meshfree method, to simulate the fluid-structure-seabed interaction.…”

“…The issue collected 14 papers that cover different aspects of marine engineering geology and geotechnics using different approaches. Some of them used numerical simulations [1][2][3][4][5], some conducted laboratory experiments [6][7][8][9][10], and others acquired and analyzed field or laboratory tests to establish a theoretical modeling framework for predicting marine sediment properties and the potential hazards [11][12][13][14]. Moreover, with a timely and well-organized publication, it is believed that the state-of-the-art data, analyses, and methodologies presented in this Special Issue could be of great interest to all readers of Journal of Marine Science and Engineering.…”

Wave-Induced Instantaneous Liquefaction of a Non-Cohesive Seabed around Buried Pipelines: A Liquefaction-Associated Non-Darcy Flow Model Approach

“…For the case of a pure seabed without a structure, several analytical solutions have been developed under various conditions [12][13][14][15]. However, for a seabed including structures such as submarine pipelines [16][17][18][19][20][21][22][23][24][25][26], breakwaters [27][28][29], coastal slopes [30], offshore wind turbine foundations [31][32][33][34][35][36][37], gravity-based structure (GBS) offshore platforms [38], dumbbell-shaped cofferdams [39], and immersed tunnels [40,41], the presence of the structures complicates the boundary conditions, generally requiring numerical methods for analyses. Recently, Li et al [42] developed an open-source numerical toolbox for simulating the interaction between a porous seabed, waves, and structures.…”