The mechanism of steady friction between seabed pipelines and clay soils

Abstract

The large-amplitude lateral soil resistance between an on-bottom pipeline and the seabed is an important design parameter in assessing pipeline behaviour during lateral thermal buckling or under the impact of a submarine slide. This paper describes a series of centrifuge model tests that shed light on the underlying behaviour during large-amplitude lateral pipe movement. It is shown that at large displacements the lateral response is governed predominantly by the passive resistance of the growing berm of soil ahead of the pipe. Using a new analysis of this growing soil berm, based on conservation of volume, the 'local' embedment of the pipe relative to the top of the idealised soil berm is defined. In this way, the normalised lateral pipe-soil resistance, H/s u D, from tests encompassing a range of pipe weights and initial embedments follows a single trend line. This idealisation of the response is more consistent than the usual terminology of a pipe-soil friction factor.

Numerical simulations of pipe–soil interaction during large lateral movements on clay

“…17). The White & Dingle (2011) and SAFEBUCK Phase II methods are accurate on average, but show more scatter than the method set out in this paper. 4 on average.…”

“…The concept of effective embedment was proposed by White & Dingle (2011), and is shown schematically in Fig. The concept of effective embedment was proposed by White & Dingle (2011), and is shown schematically in Fig.…”

“…It is now well known that the resistance from soil during lateral movement is not governed by a Coulomb friction force at the pipe/soil interface, as if the seabed were a rigid plane. The passive resistance from the soil berm ahead of the pipe governs the lateral pipe-soil interaction force White & Dingle, 2011). This initial embedment has a significant influence on the lateral pipe resistance.…”

Finite element modeling of partially embedded pipelines in clay seabed using Coupled Eulerian–Lagrangian method

“…Theoretical modeling includes the models based on bearing capacity equations, upperand lower-bound plasticity models and slip-line field theory (e.g., Small et al 1972;Murff et al 1989;Aubeny et al 2005;Zhao et al 2009). The physical modeling includes small-and large-scale modeling (SINTEF 1986a(SINTEF , 1986b(SINTEF , 1987Dunlap et al 1990;AGA/PRC 1992;Cheuk et al 2007;Cardoso and Silveira 2010) and centrifuge modeling (e.g., Dingle et al 2008;Hu et al 2009;White and Dingle 2011). Some empirical models have also been proposed based on laboratory tests and field data (Verley and Lund 1995).…”

“…The lateral resistance has also been modeled by previous researchers in theoretical framework using frictional law, plasticity theorem or upper-bound theorem, and energy equilibrium principle (e.g., Karal 1977;Cheuk et al 2007;White and Cheuk 2008). Small-to large-scale physical tests (Lyons 1973;SINTEF 1986aSINTEF , 1986bSINTEF , 1987Cheuk et al 2007) and centrifuge model tests (Dingle et al 2008;White and Dingle 2011) were conducted to understand this interaction mechanism. Moreover, FE analyses have been performed for lateral movement of pipelines in various soil conditions (e.g., Merifield et al 2008;Wang et al 2010;Chatterjee et al 2012b).…”