波浪作用下黄河口多层粉质土海床动力响应特征差异性分析

以黄河水下三角洲埕岛海域5种典型层序粉质土海床为模型，以Biot理论为基础，采用有限差分法计算10m深度内海床土应力场、位移场和超静孔隙水压力场分布，并与实际观测结果进行对比。研究揭示在波浪荷载作用下，多层海床土位移、孔隙水压力除在表层粉质土中出现1个极大值点外，在下覆软弱层中还将出现第2个极大值点，而应力在界面位置将急剧减小。表层粉质土中出现的第1个极值是引发小规模浅表地质灾害的动力学因素，而大规模地质灾害的发生和下覆软弱层中第2个极值直接相关。海床土沉积层序对土层稳定性影响大，其中“上硬下软”的沉积结构最不稳定，在强浪作用下容易发生大规模地质灾害。

Differences in dynamic response characteristics of multi-layer silty seabed under waves in Yellow River Estuary

Based on a model for 5 typical sequences of silt seabed in Chengdao sea area in subaqueous Yellow River Delta and the Biot's theory, numerical simulation in the 10 m deep-range is done to calculate the stress field, displacement field and excess pore water pressure of seabed. The calculated results are compared with the actual observed ones. This study reveals that under the wave loads, the displacement and the pore water pressure of the multi-layer seabed have the first extreme value in surface silty layer, then comes the second extreme value in the next “weak” layer, and stress will be reduced sharply at the interface position. The first extreme value is the dynamic factor for small geological disasters in the surface layer, and the second extreme value directly leads to large-scale geological disasters. The sedimentation sequences play a key role in the stability of the seabed, and the “upper hard-lower soft” structure is most unstable, where large-scale geological disasters will happen after strong wave action.