波浪作用下黄河三角洲海底塌陷凹坑成因机制与评价

he genesis mechanism and estimation method of pockmarks in the subaqueous Yellow River delta are investigated experimentally and theoretically, in which the wave-induced seepage is particularly considered. First of all, laboratory simulation tests were carried out to explore the response of silty seabed under cyclic loads, in which the layers and the saturation of seabed were considered. Excess pore pressure and seepage-related phenomenon was observed. The excess pore pressure was found to decrease more rapidly at the surface layer and the scale of seepage channels would be bigger with bigger amplitude of the cyclic loads and lower saturation of the underlying layer. In addition, the relationship between wave-induced seepage and pockmark was discussed, and the estimation of wave-induced seepage was proposed. Then, Mathematical model to simulate wave-induced excess pore pressure in the seabed was given. The model was then verified and corresponding parameters were calibrated by comparing with the laboratory tests results. Furthermore, the model was applied to the on-site Yellow River delta, in which different wave conditions and different stratifications of the seabed were considered. The genesis mechanism of pockmarks was summarized through the calculated results and the existing in-situ investigations. The wave-induced seepage in the seabed is a direct cause of the pockmarks in the subaqueous Yellow River delta; Extreme storm waves are necessary external factors; The surface hard layer and the underlying unsaturated weak layer would be certain internal factors; Scour and transport that caused by wave and current would be factors that contribute to the late reformation of the pockmarks in the subaqueous Yellow River delta.