【摘要】 深水海底管线的底部稳定性受管线的竖向贯入深度和阻力影响。采用耦合欧拉-拉格朗日法(CEL)模拟黏土中海底管线竖向大变形贯入过程,并通过子程序VUSDFLD研究土体的应变率效应和应变软化对管线承载力的影响;分析了贯入过程中管线两侧隆起土体提供的阻力,并对其进行了敏感性分析,提出了表面隆起承载力系数的公式。研究结果表明,管线承载力系数随土体应变率的增大而显著增加;土体灵敏度越大,土体软化速率越快,管线的承载力系数越低。表面隆起承载力系数取决于土体的有效重度,并且贯入深度越大,土体的有效重度对表面隆起承载力的影响越明显。通过拟合数值结果,得到了表面隆起承载力表达式。更多还原

【Abstract】 The on-bottom stability of deepwater seabed pipelines is affected by the vertical penetration depth and resistance. In this study, the coupled Eulerian-Lagrangian approach(CEL) was used to simulate the vertical penetration of pipelines in cohesive soil,and the effects of strain rate behavior and strain softening on bearing capacity of pipelines were studied by subprogram VUSDFLD.The resistance provided by the heaved-soil on both sides of the pipeline during the penetration process was analyzed and the sensitivity analysis of the resistance was implemented, then a surface heave capacity factor was proposed. Results indicated that bearing capacity factor of the pipeline increases significantly with the increase of strain rate parameter. A high sensitivity of soil leads to a fast softening rate of soil and a low bearing capacity factor of pipeline. The surface heave capacity factor mainly depends on the submerged weight of the soil. Moreover, the greater the penetration depth, the more obvious the effect of the submerged weight of soil on the bearing capacity of surface heave. An expression describring the surface heave capacity is developed by fitting the numerical results.更多还原