In-situ tests on pore-water pressure response and consolidation mechanism of surface sediments in tidal flat of Yellow River Delta under tide and wave loading

In order to study the pore pressure response and consolidation mechanism of the surface sediments in the tidal flat of the Yellow River Delta under the action of wave and tide loading, the fluid sediments imitating the rapidly deposited seabed silty soils are made in situ, and they are promptly filled into a one-meter deep pit excavated at the tidal flat. By using the static cone penetration tests and the pore water piezometer tests, a comparative study is conducted about the pore-water pressure responses of pit soils and the tidal flat soils under the action of tide and wave loading, meanwhile the non-uniform consolidation mechanism of the tidal flat soils is discussed. It is shown that the pore-water pressure responses between the the tidal flat soils and the pit soils are different under the tide loading, in the process of rising and falling tide, the excess pore-water pressure of the pit soils undergoes negative-zero-positive changes, and it is equivalent to a process of loading and unloading, however, the tidal flat soils only produce negative excess pore-water pressure. Under the coupling action of tide and wave loading, the accumulation of pore water pressure is obvious in the surface soils of tidal flat, and the maximum excess pore water pressure is generated near a depth of 0.3 m. The strength of the tidal flat soils in the Yellow River Delta presents the phenomenon of high-low-subhigh non-uniform consolidation along the depth, and the mechanism of this phenomenon is related to the characteristics of pore pressure responses of tidal flat soils under the tide loading and coupling action of tide and wave loading, especially near the surface of 0.3 m of soils, which is significantly affected by long-term wave loading and a hard shell layer is formed.