In this study, unlike most previous investigations have limited to the regular wave conditions or combined wave and current conditions, a numerical model for seabed response around a pipeline in a trenched layer due to random waves is established. Three different wave spectra including the JONSWAP spectrum, Bretchneider–Mitsuyasu spectrum and Pierson–Moscowitz spectrum are considered in the present model for the simulation of random waves. Numerical examples indicate that the irregular wave-induced pore-water pressure can randomly amplify the upward gradient of the pore-water pressure in the porous seabed, making the backfill sand layer more likely to be liquefied at a deeper depth. It is observed that the upper width of the trench layer becomes larger once the seabed liquefaction occurs, which can effectively prevent the seabed liquefied surface from penetrating into the bottom of the pipeline by increasing the backfill thickness to twice of the pipe diameter. The superimposition of the irregular waves on the following current has more significant effect on the maximum-development of the seabed liquefaction depth, which is particularly obvious when the sand-bed is in the random wave system by using the JONSWAP spectrum.

在这项研究中，不同于以往的大多数研究仅限于规则波浪条件或波浪和电流组合条件，建立了随机波引起的沟槽层管道周围海床响应的数值模型。在本模型中，为了模拟随机波，考虑了三种不同的波谱，包括JONSWAP谱，Bretchneider-Mitsuyasu谱和Pierson-Moscowitz谱。数值算例表明，不规则波浪引起的孔隙水压力可以随机放大多孔海底孔隙水压力的向上梯度，使回填砂层更可能在更深的深度被液化。可以看出，一旦发生海底液化，沟槽层的上部宽度就会变大，通过将回填厚度增加到管道直径的两倍，可以有效防止海底液化表面渗入管道底部。随波叠加不规则波对海床液化深度的最大发展有更大的影响，这在使用JONSWAP谱将砂床置于随机波系统中时尤为明显。