Pipeline–soil–water interaction modelling for submarine landslide impact on suspended offshore pipelines

Abstract

The submarine landslide is one of the major geohazards in deep-water oil and gas developments. The impacts of glide blocks or out-runner blocks, which carry the geotechnical properties of the parent soil mass before the landslide, on pipelines normal to the direction of slide, are investigated in this study. A computationally efficient numerical modelling technique is developed using a computational fluid dynamics approach, incorporating a strain-rate and strain-softening dependent model for the undrained shear strength of clay sediment, to simulate the lateral penetration of a pipe in a clay block. The role of water in the cavity and channel formed behind the pipe during the lateral penetration on drag force is successfully simulated. Numerical simulations for varying depths of the pipe explain the change in soil failure mechanisms in which the channel behind the pipe and berm play a significant role, especially at shallow depths. As the cavity behind the pipe may not be completely filled with soil, the limitations of smooth/rough and bonded/unbonded interface conditions, as used typically in pipe–soil interaction analysis, are discussed. Based on a comprehensive parametric study, calibrated against centrifuge test results, a set of empirical equations is proposed to calculate drag force for practical applications. The effects of inertia on drag force are examined.

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

“…The hybrid geotechnical-fluid dynamics framework combines the above two mechanisms, by treating the interaction force components that arise from the viscous strength concept and the inertia separately (e.g. Randolph and White 2012;Sahdi et al 2014;Dong et al 2017;Dutta and Hawlader 2019;Fan et al 2021).…”

“…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.…”

The formation and implications of giant blocks and fluid escape structures in submarine lateral spreads

“…The nature of any impacts to seafloor structures, and also the potential for tsunamigenesis, strongly depend on the degree of landslide disaggregation, the volume and strength of the failed mass, its mobility, speed and direction of movement (e.g. Watts et al, 2005;Zakeri, 2009;Zhu and Randolph, 2010;Randolph and White, 2012;Dutta and Hawlader, 2019). For instance, highly mobile, yet relatively thin debris flows have toppled oil and gas platforms, and ruptured pipelines in the Gulf of Mexico (e.g.…”

“…More specifically, the risks to seafloor infrastructure, and the tsunamogenic potential are dependent on the degree and rate of landslide disaggregation, the volume and strength of the failed mass and the speed and movement direction (e.g. Dutta & Hawlader, 2019; Randolph & White, 2012; Watts et al., 2005; Zakeri, 2009; Zhu & Randolph, 2010). For instance, highly mobile, yet relatively thin debris flows have toppled oil and gas platforms, and ruptured pipelines in the Gulf of Mexico (e.g.…”

Numerical Study on Interaction between Submarine Landslides and a Monopile Using CFD Techniques

“…Next, some researchers extended the previous works to study the normal and longitudinal interaction forces at different impact angles of submarine debris flows [23][24][25]. Afterwards, more factors on the drag force, such as suspension height [26][27][28], temperature of submarine debris flows [29], shape of the pipeline [30][31][32], strain-softening effects on soil strength [33], were also considered. In addition, some studies [34,35] used the material point method to investigate impact forces on pipelines, while an explanation of the mechanism of peak force was provided by [36,37].…”