浅水区海底管道周围海床孔压分布数值计算研究

Numerical Study on the Pore Water Pressure Distribution in Seabed Around Pipelines in Shallow Water

针对我国海上油田开采起步较晚,大部分油田处于浅水区的情况,在研究管道稳定性时,应充分考虑浅水区波浪的影响。考虑管道为弹性体,根据Biot固结理论,基于近似椭圆余弦波理论,利用大型有限元软件ABAQUS建立浅水区海底管道周围海床孔隙水压力数值计算模型,讨论浅水波作用下海底管道周围海床超静孔隙水压力的分布规律,分析管-土接触作用、海床土性质以及埋置深度等因素对管道周围海床土超静孔隙水压力分布的影响。计算结果表明:管道与海床的相互接触效应对于波浪作用下管道周围海床中超静孔隙水压力的分布影响非常小;海床的渗透特性、孔隙率、弹性模量以及埋置深度对管道周围海床中超静孔隙水压力分布有明显影响,海床的渗透性越低,弹性模量越小,埋置深度越浅,管道越容易发生失稳。

Offshore oil field exploitation in China started relatively late than other countries,and most oil fields locate in shallow waters.So shallow water wave effect should be fully considered when we study on the stability of submarine pipeline.Based on the Biot s theory of consolidation and the approximate cnoidal wave theory,numerical model was established to calculate the pore water pressure distribution in seabed around submarine pipelines in shallow water in view of elasticity of pipelines by using the finite element software ABAQUS.The distribution law of the wave induced excess pore water pressure around the seabed and the influence of pipe-soil contact,seabed soil properties and embedment depth on the excess pore water pressure of seabed soil around the pipeline were analyzed.The calculating results shows that the pipe-soil contact effects has little influence on the excess pore water pressure around the pipeline.However,the permeability,porosity,elastic modulus of seabed and embedment depth have significant influence on the excess pore water pressure around the pipeline.The pipeline will be more probably unstable when the permeability of the seabed is weaker,the elastic modulus is smaller and the buried depth is shallower.