Preliminary Study On Physical Characteristics Of Sediment Deposition In The Three Gorges Reservoir

The general characteristics of sediment distribution in the reservoir area of the Three Gorges Reservoir are characterized by discontinuous broad valleys and siltation,and there is no cumulative siltation in the canyons.The proportion of clay minerals in the reservoirs increases,which means that the potential risk of water eutrophication in the Three Gorges reservoir will increase.The dry density of reservoir sediment is affected by many factors,and it is related to the accurate calculation of reservoir sedimentation.Based on the analysis of the physical characteristics of the sediments in the characteristics section(points)of the Three Gorges Reservoir,this paper discusses the feasibility of the reservoir in situ sampling around the reservoir sedimentation effect of dry density changes and designs a set of simulation test equipment which can provide long-term observations with dry density change of silt under deep flood conditions and carried out a series of laboratory experiment.7 kinds of hydraulic pressure conditions were set up to simulate the change of dry density of the sediment samples before the Three Gorges reservoir area and Huanghuacheng.In this paper,the following results are obtained:(1)The characteristics of siltation minerals are analyzed by sampling the silt at the same time in the four consecutive high/low water level along each section.(2)The indoor simulation test of dry density of the silt in the reservoir was carried out.The results showed that the rate of compaction is developed very quickly in 2 days and then entered into a stable slow dense process.When the water depth is more than 150 m,the compaction process and the dry density change are relatively fast.The water pressure only has a significant effect on the initial low concentration and dense process,and little effect of the high density and dry density after stable compacting process.The ratio of sample,concentration and particle size have significant influence on the initial change rate of dry density.(3)The characteristics,difficulties and insufficient of the in situ dry density sampling are validated compared with the current sampling device,and a new idea of research and development is put forward "under the action of self-weight rotation into the sample" program for a feasibility analysis.The research in this paper can provide reference for the analysis and calculation of large reservoirs.