半埋式海底管道周围海床瞬态液化稳定性研究
Numerical Study on Wave-induced Oscillatory Soil Liquefaction around a Partially Buried Pipeline

为研究波浪荷载作用下半埋式海底管道周围海床的瞬态液化稳定性，通过动量源函数法进行数值造波，以LSM法追踪波浪自由液面，利用有限元法求解海床控制方程，建立了波浪-海床-半埋式海底管道相互作用的二维数值模型.将求解的波浪模块中的海床表面压力作为海床模块的边界条件，得到海床中的超孔隙水压力及有效应力，研究了回填高度及波浪特性对半埋式海底管道周围海床稳定性的影响.研究结果表明：波浪特性对半埋式海底管道周围海床瞬态液化稳定性影响较大，管道底部海床瞬态液化深度幅值随波高及波浪周期增大而增大；当波高为3 m、波浪周期为10 s时，管线底部海床液化深度可达0.92 m；当回填高度大于临界回填高度时，管道底部海床不会发生瞬态液化现象.
： To examine the oscillatory soil response around a partially buried pipeline under wave load, a numerical model for wave-seabed-pipeline interactions was proposed using the finite element method, in which the momentum source function was added to the Reynolds-averaged Navier-Stokes (RANS) equation to generate waves, and the Level Set Method was used to track the water free surface. The wave pressure calculated from the wave model was applied to be the seabed model boundary condition to determine the wave-induced soil response. Based on the proposed model, a set of analyses regarding the effects of backfill thickness and wave characteristics on the oscillatory soil response was carried out. Numerical results indicate that wave characteristics can significantly affect the wave-induced oscillatory soil response, and that the liquefaction depth increases with the increment of wave height and period. The liquefaction depth at the bottom of the pipeline can reach 0.92 m when the wave height is 3 m and the wave period is 10 s. Moreover, the soil at the bottom of the pipeline can be prevented from being liquefied when the backfill thickness is greater than the critical backfill thickness under a certain soil condition. In other words, the soil at the bottom of the pipeline can be protected by increasing the backfill thickness