孤立波作用下埋管斜坡海床及海底管道的响应分析

Solitary Wave-Induced Response of Sloping Seabed with a Buried Pipeline

通过建立孤立波-斜坡海床-海底管道耦合模型,研究在孤立波作用下近岸浅水区域埋管周围斜坡海床土体的孔隙水压力响应和海底管道的受力及位移.采用考虑k-ε湍流的Navier-Stokes方程模拟孤立波在海底斜坡上的破碎、爬升及回落过程,并且通过计算获得斜坡表面波压力;基于Biot固结方程,建立波压力作用下的斜坡模型;基于线弹性理论,利用偏微分方程建立海底管道模型;计算分析埋管海床土体的孔压响应特征及管道的受力与变形;通过与文献试验数据和解析解的对比,验证了该分析方法与模型的准确性;利用验证后的数值模型,计算在孤立波作用下斜坡海床埋置管道周围土体的孔隙水压力响应、纵向有效应力响应、管道的纵向受力及位移.数值模拟结果表明:在孤立波回落阶段,埋置于斜坡海岸线附近的管道周围土体孔压下降明显,管道出现较大上浮,相较于水平海床和斜坡坡脚,此处管道的受力和位移情况最为不利.另外,管道埋深、土体参数,以及波浪的破碎、爬升及回落过程都对计算结果有着重要的影响.

Through the solitary wave-sloping seabed-submarine pipeline coupling model,the pore water pressure response,stress and displacements of submarine pipelines around the buried pipelines in shallow coastal areas under solitary waves are studied.The Navier-Stokes equations considering k-εturbulence are used to simulate the break,rise and fall of solitary waves on the gentle slope of the seabed.The surface pressure of the gentle slope is calculated.Based on the Biot consolidation equation,the slope model under the wave pressure is established.Based on the linear elasticity theory,the pipeline model is established by partial differential equation.The pore water pressure response characteristics,stress and deformation of the buried pipe seabed soil are calculated and analyzed.Compared with the test data and analytic solutions in literatures,the accuracy of analytical method and the model is verified.By using the validated numerical model,the pore water pressure response and the vertical effective stress response of soil around the embankment on gentle slope seabed under the action of solitary waves are calculated.The vertical force and displacement deformation of the pipelines are also calculated.The results show that,during the solitary wave run-down phase,the pore pressure around the pipelines buried near the coastline of the slope descends obviously,and the pipelines go up greatly.Compared with the situation of buried horizontal seabed and slope foot,the stress and displacement of the pipelines are the most unfavorable here.Besides,pipeline depth,soil parameters and the break,rise and fall of wave have a significant impact on the calculation results.