In situ experiment of wave-induced excess pore pressure in the seabed sediment in Yellow River estuary

Both the special engineering geological properties and the complex engineering dynamic stability problems are closely related to the wave-induced dynamic response of pore pressure in seabed sediment in the Yellow River estuary. Four typical sites on the intertidal flats of the Yellow River delta are selected to simulate the wave action on the intact seabed sediments. Various testing methods, such as pore water piezometer test, field sediment strength test and sampling/laboratory geotechnical experiments, are employed to determine the variations in pore pressure and strength of the undisturbed seabed sediments at different stages under the cyclic loading. It is shown that during the cyclic loading process, the excess pore pressure response of undisturbed seabed sediment can be separated into 5 stages including gradual accumulation, partial dissipation, rapid accumulation, accumulated liquefaction and complete dissipation, which correspond to five processes of sediment strength variation including attenuation, increase, attenuation, loss and recovery, respectively. The grain size composition and structural strength dominate the excess pore pressure response. The wave-induced liquefied depth of intact seabed sediment is significantly affected by the initial physical properties such as dry density, void ratio, saturation degree, etc. To a large extent, the relative amount of fine grained components also controls the liquefaction characteristics of sediment in the Yellow River estuary.