Experimental study on impact of marine hydrodynamics on strength of seabed sediments in the Yellow River estuary

Based on in-situ tests, the impact of marine hydrodynamics, such as waves and tides, on the consolidation process of rapidly deposited sediments is studied. On the tidal flat of Diaokou delta-lobe, a 2 m×1 m×1 m test pit filled with fluid sediments prepared by the in-situ silt is excavated. The test pit is divided into two parts, one of which is covered with a plate to eliminate the influence of the hydrodynamics. By some field test methods, static cone penetration tests, field vane shear tests and pore water piezometer tests, the variation of sediments strength and pore water pressure of the both parts are real-time measured to study the consolidation process of the prepared sediment under the gravity and marine hydrodynamics. It is shown that the self-consolidated sediments have a high consolidation rate which can reach 37% in 72 h and so does the pore water pressure which nearly disperses over in about 142 h, while under the hydrodynamics, the consolidation rate reaches 52% in 72 h and the pore water pressure disperses over in about 195 h. In the consolidation process, the waves and tides whose ability to raise the strength of the sea-bed soils is five times as much as that of self-consolidated play a decisive role at the initial stage, and with the extension of the depth, the role of the hydrodynamics is reduced. With the continuation of the consolidation process, the trend of the strength increase of the surface sediments gradually slows down under the water dynamics, while the sediments whose depth is below 50 cm is in an opposite way. As a result, the rapidly deposited silts show a non-uniform consolidation state, and the crust is gradually formed. The results provide a reference for studying the role of the hydrodynamics in the soil consolidation process. The impact of different hydrodynamics on the soil consolidation requires further studies.