Study on the motion patterns of shallow-embedded pipelines in sand

Abstract

Pipe-soil interactions are a crucial consideration in the realization of shallow-embedded pipelines’ in situ stability, and the choice of pipe-soil interaction model is correlated with the distinction between “light” and “heavy” pipe motion patterns. Based on the difference in the motion pattern of a shallow-embedded pipeline in sandy soil after a breakout, a numerical model of pipe-soil interaction is constructed. The influencing factors of different motion patterns are studied, while taking into account the shear expansion or shrinkage characteristics of sand. Accordingly, a method of discriminating pipeline motion patterns is proposed. The results show that the motion pattern of a shallow-embedded pipeline in sandy soil depends on the relative weight of the pipe and soil bearing capacity, that the smaller the embedment, the easier the “heavy pipe” motion pattern appears, and that the critical pipe weight required for “heavy pipe” motion increases with initial sand density and pipeline embedment depth.

HIGHLIGHTS

1. This paper outlines the different motion patterns of pipelines during breakout stage in sandy soil.

2. A numerical model that can consider the mechanical response of sand in pipe-soil interaction is established, and the factors influencing the light and heavy pipe motion patterns of submarine pipelines are analysed.

3. Based on the numerical results, the empirical and theoretical formulas for assessing the critical pipe weight in sand are proposed. These formulas offer a basis for distinguishing between the “light pipe” and “heavy pipe” motion patterns of shallow-embedded pipes in sand.

Keywords:

• Pipe-soil interaction
• hypoplastic constitutive model
• sand
• light pipe
• heavy pipe

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors are grateful for the support provided by the National Natural Science Foundation of China [Grant no. 42207183] and the study is supported by the China National Postdoctoral Program for Innovative Talents [Grant No. BX2021213].