砂土海床海底管道贯入的数值模拟

Numerical simulation of submarine pipeline penetration in sandy seabed

为预测砂土海床海底管道贯入深度,在ABAQUS下建立了砂土海床海底管道贯入的耦合欧拉-拉格朗日有限元模型,模拟海底管道在风浪流及自重等荷载作用下贯入砂土海床的过程,研究了管-土界面摩擦系数、砂土内摩擦角、剪胀角及弹性模量对管道贯入深度的影响。结果表明,在海底管道贯入过程中,管道两侧海床隆起,在海床土体内形成了自管道底部延伸至海床表面的连续滑动面,砂土破坏表现为整体剪切破坏形式;管-土界面摩擦系数、砂土内摩擦角及剪胀角均会影响砂土海床海底管道贯入深度,其中砂土内摩擦角对海底管道贯入深度影响最大,而砂土弹性模量则对海底管道贯入深度没有显著影响。海底管道贯入阻力随管-土界面摩擦系数、砂土内摩擦角和剪胀角增加而呈幂函数增大。所提海底管道贯入深度预测公式考虑了管-土界面相互作用和砂土力学特性的影响,能准确预测砂土海床中管道的贯入深度,可为砂土海床海底管道在位稳定性评估提供基础数据。

In order to predict the penetration depth of submarine pipeline on sandy seabed, a coupled Eulerian-Lagranginan finite element model of submarine pipeline penetration on sandy seabed was established under ABAQUS to simulate the process of submarine pipeline penetration into sandy seabed under the loads such as wind, wave, current and self-weight.The effect of the friction coefficient of the pipe-soil interface, the internal friction angle, the dilation angle, and the elastic modulus of sand on the penetration depth of the pipeline was studied.The results show that, during the penetration of the submarine pipeline, the seabed on both sides of the pipeline is uplifted, and the seabed soil forms a continuous sliding surface extending from the bottom of the pipeline to the surface of the seabed.The soil failure is in the form of general shear failure.The friction coefficient of the pipe-soil interface, the internal friction angle and the dilation angle of the sand all affect the penetration depth of submarine pipeline on sandy seabed.The internal friction angle of sand has the greatest impact on the penetration depth of the submarine pipeline, while the elastic modulus of sand has no significant effect on the penetration depth of the submarine pipeline.The penetration resistance of the submarine pipeline increases as a power function with the increase of the friction coefficient of the pipe-soil interface, the internal friction angle and the dilatation angle of the sand.The proposed prediction formula can accurately predict the penetration depth of pipelines on the sandy seabed by considering the effects of pipe-soil interaction and sand mechanical properties, and the calculation results provide basic data for in-situ stability evaluation of submarine pipelines on the sandy seabed.