波浪引起的海底管线周围海床动力响应分析

WAVE-INDUCED DYNAMIC RESPONSE OF SEABED AROUND SUBMARINE PIPELINE

在目前的海床–管线相互作用问题研究中,管线与海床交界面一般假定为不可滑动,没有考虑海床–管线接触效应,同时也没有考虑土体和管线加速度效应对海床动力响应的惯性影响,同工程实际情况存在较大差异。为此,分别基于Biot动力固结理论和弹性动力学理论列出海床和海底管线的控制方程,进而根据摩擦接触理论考虑海床与管线之间的相互作用效应,建立海床–管线相互作用的有限元计算模型。根据计算发现,海床–管线接触效应对管线附近海床中的有效应力影响显著,不同的管沟形状对海床中由波浪所引起的超静孔隙水压力及有效应力影响显著。

The evaluation of wave-induced excess pore water pressure and effective stresses are recognized as an important factor in the design of submarine pipelines. In most previous investigations for the seabed-pipeline interaction, the effect of pipeline on dynamic response of seabed has been usually ignored; and nonslip condition is mainly assumed at the interface between pipeline and seabed soils. The effect of full interaction between seabed and pipeline has not been considered in the analyses of stresses and deformations of the seabed and submarine pipeline. Furthermore, the inertia effects of both accelerations of seafloor soils and pipeline on response of seabed have not been taken into account in most previous investigations. The governing equations of the seabed and pipeline are formulated respectively based on the Biot＇s theory of dynamic consolidation of two-phase media and principle of elastic dynamics. The seabed-pipeline interaction problem is investigated by using the friction contact theory; and numerical formulations based on FEM are established. Based on the computed results, it is found that the soil-pipeline interaction plays an important role in effect stresses of the seabed around pipeline; and the wave-induced excess pore water pressure along the pipeline surface is significantly affected by the shape of the trench layer in the vicinity of the bottom of the pipeline.