<p>Submarine pipelines are one of the most efficient modes for the oil and gas in offshore environments. During operation cycles, pipelines may undergo thermal expansion induced by the high temperatures and high pressures (HTHP), which can cause them to experience combined vertical (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$V$</EquationSource> <EquationSource Format="MATHML"><math> <mi>V</mi> </math></EquationSource> </InlineEquation>) and horizontal (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$H$</EquationSource> <EquationSource Format="MATHML"><math> <mi>H</mi> </math></EquationSource> </InlineEquation>) loading. The bearing capacity of pipelines under this complex loading scenario is typically described using the <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$VH$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">VH</mi> </mrow> </math></EquationSource> </InlineEquation> failure envelopes. Although numerous research studies have been carried out on the structure and failure mechanisms of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$VH$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">VH</mi> </mrow> </math></EquationSource> </InlineEquation> failure envelopes, most of them are deterministic analyses. To remedy this situation, two-dimensional (2D) random finite element analyses were repeatedly conducted in this paper within a Monte Carlo framework. The results indicate that the soil strength randomness can decrease the pipeline’s uniaxial bearing capacity of the pipeline as well as modify the size and shape of the <InlineEquation ID="IEq5"> <EquationSource Format="TEX">$VH$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">VH</mi> </mrow> </math></EquationSource> </InlineEquation> failure envelopes compared to deterministic soil. The <InlineEquation ID="IEq6"> <EquationSource Format="TEX">$VH$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">VH</mi> </mrow> </math></EquationSource> </InlineEquation> failure envelopes at various failure probabilities are presented, and it is observed that the factors of safety suggested by the guidelines do not fulfill the pipeline design requirements. Consequently, a procedure for determining the design <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$VH$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">VH</mi> </mrow> </math></EquationSource> </InlineEquation> failure envelope of pipelines in random soil under combined <InlineEquation ID="IEq8"> <EquationSource Format="TEX">$VH$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">VH</mi> </mrow> </math></EquationSource> </InlineEquation> loads is developed. These findings offer valuable insights for pipeline design.</p>

Determination of failure envelope for submarine pipeline in spatially variable clay

期刊论文
发表日期：

2026年3月21日

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Fei Liu,
Chao Fan Liu,
Yu Zhou Sun,
Jiang Tao Yi,
Xiang Ming Zhou,
Long Fei Wang

摘要

Submarine pipelines are one of the most efficient modes for the oil and gas in offshore environments. During operation cycles, pipelines may undergo thermal expansion induced by the high temperatures and high pressures (HTHP), which can cause them to experience combined vertical ( $V$ $V$ ) and horizontal ( $H$ $H$ ) loading. The bearing capacity of pipelines under this complex loading scenario is typically described using the $VH$ $VH$ failure envelopes. Although numerous research studies have been carried out on the structure and failure mechanisms of $VH$ $VH$ failure envelopes, most of them are deterministic analyses. To remedy this situation, two-dimensional (2D) random finite element analyses were repeatedly conducted in this paper within a Monte Carlo framework. The results indicate that the soil strength randomness can decrease the pipeline’s uniaxial bearing capacity of the pipeline as well as modify the size and shape of the $VH$ $VH$ failure envelopes compared to deterministic soil. The $VH$ $VH$ failure envelopes at various failure probabilities are presented, and it is observed that the factors of safety suggested by the guidelines do not fulfill the pipeline design requirements. Consequently, a procedure for determining the design $VH$ $VH$ failure envelope of pipelines in random soil under combined $VH$ $VH$ loads is developed. These findings offer valuable insights for pipeline design.