随机波作用下埋管海床动态响应及液化研究

基于广义Biot动力理论和Longuet-Higgins线性叠加模型,构建波浪-海床-管线动态响应的有限元计算模型,求解随机波作用下,多层砂质海床中管线周围土体孔隙水压力和竖向有效应力的分布。采用基于超静孔隙水压力的液化判断准则,得出液化区的最大深度及横向范围,从而判断海床土体液化情况。考虑海洋波浪的随机性,将海床视为多孔介质,海床动态响应计算模型采用u-p模式,孔隙水压力和位移视为场变量。并考虑孔隙水的可压缩性、海床弹性变形、土体速度、土体加速度以及流体速度的影响,忽略孔隙流体惯性作用。参数研究表明:土体渗透系数、饱和度以及有效波高等参数对海床土体孔隙水压力、竖向有效应力和液化区域分布有显著影响。

Numerical study of random wave induced seabed-pipeline response and liquefaction

Based on general Biot''s dynamic consolidation theory and Longuet-Higgins random wave theory, a finite element calculating model was established for random wave induced seabed-pipeline dynamic response and liquefaction. The model simulated the distribution of pore pressure, vertical effective stress surrounding the pipeline under random wave. The liquefaction criteria based on excess pore water pressure was adopted to obtain the maximum depth and crosswise range of liquefaction zone. The stochastic feature of ocean wave loading had been taken into account and the seabed was treated as porous medium. In the calculation model u-p mode formulations were adopted, in which both pore pressure and displacement were defined as field variables. Besides, the influences from compressibility of pore water, elastic deformation of seabed, soil velocity, soil acceleration and fluid velocity were considered. However the inertia effect of pore fluid was ignored. The results show that the parameters of seabed, including the permeability, degree of saturation and effective wave height, influence the distribution of pore pressure, vertical effective stress and liquefaction zone significantly.