Research Of Heterogeneity Consolidation Mechanics Of Subsurface Sediment On The Subapueous Delta Of Yellow River, China

The dissertation was relied on the project of National Nature Science Foundation Project Formation and failure of hard crust on the subaqueous delta of Yellow River (Contract No.141720888), and objective to research the heterogeneity consolidation of subsurface sediment on the Subaqueous Delta of Yellow River, that was induced by wave loading action.The surfacial sediment on the Yellow River Delta is so sensitive to ocean hydrodynamic condition, especially waves that soil failed and came into being a lot of unstable features: bumps and hollows, flute and groove cast of silt and collapse. The disruptive phenomenon is related to the change of sediment strength under the wave loading tightly. In the former researches, scholars mainly studied following static aspects: topography and geomorphy, ocean hydrodynamic condition and soil engineering features. There is a lack of researches on the heterogeneity of sediment strength and the regular distributing characteristics.The paper includes eight parts: the first part shows the significance of the research, researching situation and its comment; the second one summarizes of the subsurface engineering geology environment on the subaqueous delta of Yellow River; the third chapter is the in-situ testing investigation of the heterogeneity properties of the sediments; the next part shows the laboratory test analysis of soil heterogeneity characteristics; the fifth part introduces the laboratory simulation test of the soil dynamical consolidation under the recycle loading; the sixth is the research of the distribution of holes on the delta and their influence to the soil consolidation; the seventh part discusses the heterogeneity from the view of microscope; the last of the paper is the analysis of numerical simulation of heterogeneity of sediment.The in-suit research areas locate on the inter-tidal flat forms with different consolidation time and different hydrodynamic conditions. In order to investigate the heterogeneity characteristics of the subsurface sediments, many tests have been carried out including portable cone penetration test, cone penetration test, soil vibration test, pore pressure measurement, hole drilling and catching undisturbed soil samples for soil test and microstructure observation.Through the above research work, we conclude the rule of heterogeneity characteristics of subsurface sediment on the delta of Yellow River. The numerical simulation is carried out, based on Biot's consolidation and simplified sea-bed to two dimensional sea-bed. Besides, we also discuss the reason of this heterogeneity from the view of microscope. It is found that the heterogeneity characteristics of subsurface sediment are related to the secondary change of the wave loading.A serial of interesting phenomenon and innovative realizations were obtained about the wave-induced heterogeneity properties of subsurface sediment on the basis of in-situ investigation in the inter-tidal platform of the Yellow River delta. They can be concluded as below:(1)a serial of in-situ tests shows there are obvious heterogeneity characteristics of the subsurface sediment, whether in horizontal direction or vertical.(2) The result of laboratory experiments of samples also shows the heterogeneity of the basic physical index along the depth.(3) In the simulation experiment, the vary of the characteristics of the sample with different depth is found.(4) The holes distributed on the flat form also influenced the development of the heterogeneity.(5) From the microscope view, the structure of soil is changed with heterogeneity due to wave loading .(6) Through the numerical method, the development of heterogeneity consolidation of soil under wave loading is simulated.This thesis is from span-new visual angle to research the character of engineeringgeology of soil induced by the wave -heterogeneity. There are innovations in research method and technology route aspect. System work is developed in the natural laboratory of the mouth in Yellow River for the thesis, which make up...