Runout prediction and dynamic characteristic analysis of a potential submarine landslide in Liwan 3-1 gas field

Abstract

A large number of submarine landslides with different scales have been identified in the canyon area of the submarine pipeline route of Liwan 3-1 gas field. There is still much chance that submarine slope failures would happen, and the following mass movement would present great risk to the submarine pipeline. In view of this, a numerical prediction method based on Eulerian-Eulerian two-phase flow model is introduced to simulate the mass movement of potential submarine landslides. The sliding soil and ambient water are respectively simulated by Herschel-Bulkley rheology model and Newtonian fluid model. The turbulence is simulated using the k-e model. Compared with both the experiment data and Bing result, the two-phase flow model shows a good accuracy, and its result is more close to the actual situation; the dynamic coupling between soil and ambient water can be effectively simulated and the phenomena of hydroplaning and head detachment can be obtained. Finally, the soil movement of a potential submarine landslide is simulated as an example, according to the seismic profile in the canyon area. The result shows that the hydroplaning occurs during the movement process. The runout distance calculated by the two-phase flow model is 877 m, which is 27.1% larger than the Bing result. However, the peak front velocity of soil is relative small, with a maximum value of 8.32 m/s. The Bing program with a simple and rapid process can be used for a preliminary evaluation, while the two-phase flow model is more appropriate for an accurate assessment. . 2015. Runout prediction and dynamic characteristic analysis of a potential submarine landslide in Liwan 3-1 gas field. Acta Oceanologica Sinica, 34 (7): 116-122,

Convenient Method for Large-Deformation Finite-Element Simulation of Submarine Landslides Considering Shear Softening and Rate Correlation Effects

“…Figures 9 and 10 show the Tresca stress and velocity distributions at different time points, respectively, in the case of S um = 5 kPa, K = 1.15 kPa/m, and S t = 4.0. It can be seen that both cases show a shallow landslide failure mode, which is consistent with the stability analysis of the submarine slope and the geophysical interpretation of existing landslide characteristics [16,[40][41][42]45]. In the case that the initial stress has not been taken into account, the self-weight load can lead to large fluctuations in the stress field.…”

“…Multibeam topography has shown that the heights of the landslide scarps, which are mainly located at the sidewall and the interfluve of the canyon, are basically between 8 and 125 m, and the maximum local slope can reach 26.6 • [43]. The soil in the Shenhu sea area has medium or high soil sensitivity based on the drilling test and the in situ CPT test [44,45], and the undrained shear strength exhibits linear and segmented linear growth with increasing burial depth. The intact undrained shear strength of the soil, S u0 , can be expressed as…”

“…As matters stand, the main methods for simulating the mass movement of submarine landslides are as follows: analytical methods based on rigid bodies [10,11], single-phase plastic fluid methods [12,13], multiphase flow methods [14][15][16][17], large deformation finite element methods [18], material point methods [19,20], discrete element methods/smoothed particle hydrodynamics [21,22], and CFD-DEM coupling methods [23,24]. As matters stand, the main methods for simulating the mass movement of submarine landslides are as follows: analytical methods based on rigid bodies [10,11], single-phase plastic fluid methods [12,13], multiphase flow methods [14][15][16][17], large deformation finite element methods [18], material point methods [19,20], discrete element methods/smoothed particle hydrodynamics [21,22], and CFD-DEM coupling methods [23,24].…”

“…Multiphase flow methods can handle interactions between sliding soil and the environmental water to a certain extent [14][15][16][17]. However, they cannot reasonably reflect the complex stress-strain relationship of the landslide mass, especially in the early phase of sliding.…”

Evaluation of horizontal submarine slide impact force on pipeline via a modified hybrid geotechnical – fluid dynamics framework

“…The potential threat of submarine slides on offshore infrastructures, such as submarine pipelines, has recently received much attention (e.g. Locat and Lee 2002;Wang and Miao 2008;Zakeri et al 2008Zakeri et al , 2009Zhu and Randolph 2010;Randolph and White 2012;Sahdi et al 2014;Yuan et al 2014;Liu et al 2015;Xiu et al 2015;Dong et al 2017;Nian et al 2018;Dutta and Hawlader 2019;Guo et al 2019;Zhang et al 2019;Fan et al 2019;Qian et al 2020), to ensure safe offshore developments. In particular, there have been a number of specialized international research initiatives [e.g.…”