Discussion on storm-induced liquefaction of the superficial stratum in the Yellow River subaqueous delta

Geological disasters on the superficial seafloor were revealed in geological investigation on the Yellow River subaqueous delta. Combined with dynamic triaxial tests and wave flume experiments, occurring conditions and forming patterns of liquefaction as well as motion of the liquefied soil were explained in this paper. Based on the viewpoint that the geological disasters were formed due to silty soil liquefaction under storm waves, re-stratification issue of the superficial stratum was analyzed. Movement of the liquefied soil agreed with the wave, leading to differentiation of the soil particles. Research issues in respect of geological, environment and engineering of storm-induced liquefaction were also discussed.

Dynamics of Bottom Boundary Layers in the Yellow River Subaqueous Delta Based on Long-Term In-Situ Observations

Objective In geo-marine science,the generalized bottom boundary layer（BBL）represents a layer between sediments and seawater.The BBL plays an important role in geological,geobiochemical,geophysical and geotechnical research because it is the connection region of hydrosphere,

Inversion and Prediction of Consolidation Settlement Characteristics of the Fluvial Sediments Based on Void Ratio Variation in the Northern Modern Yellow River Subaqueous Delta, China

The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of consolidation settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the consolidation settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-consolidation settlement(from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the consolidation settlement of unit depth is between 9.6 and 14.0 cm m^(-1). The post-consolidation settlement(from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the consolidation settlement of unit depth is between 7.6 and 13.1 cm m^(-1) under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible consolidation settlement in the later stage.

In Situ Observation of Silt Seabed Pore Pressure Response to Waves in the Subaqueous Yellow River Delta

The in situ pore pressure response of silt under wave action is a complex process.However,this process has not been well studied because of limited field observation techniques.The dynamic response process is closely related to engineering geological hazards;thus,this process must be urgently explored.A long-term in situ observational study of the silt sediment pore water pressure response process under wave action was conducted in the subaqueous Yellow River Delta.The response characteristics of pore water pressure are affected by tidal level and wave height.Tidal level affects the overall trend of the pore water pressure response,while wave height influences the amplitude of the pore water pressure response.This study revealed a significant lag effect in the pore pressure response.The transient pore pressure in the seabed did not respond immediately to the wave-induced pressure stress on the seabed surface.This phenomenon may be attributed to the change in soil permeability.The maximum response depth was approximately 0.5 m with a 2 m wave height.A concept model of silt soil pore pressure response under different types of wave action was developed.The accumulation rate of the pore pressure is less than the dissipation rate;thus,the developed model highlights the oscillation pore pres-sure response mechanism.The highlighted response process is of considerable importance to transient liquefaction and the startup process of pore pressure response.