Research On Reducing Suspended Sediment In Construction Through Blowing Sand Reclamation

The reclamation can promote the rapid development of coastal economy meanwhile;it has a series of environmental problems,such as: shoreline erosion,deterioration of water quality,decline of marine species and marine disasters.The study shows that the suspended sediment generated in the construction will have an irreversible impact on the local water environment and marine organisms in the reclamation.People should pay attention to the protection of the marine environment when they expand land use area through reclamation.How to reduce the amount of suspended sand in reclamation process has attracted the attention of scholars.Therefore,the reclamation method of suspended sediment reduction of construction technology has an important practical significance for guiding the practical engineering construction and the protection of the marine environment.At present studies about how to reduce the suspended sediment in the construction process of using landfill reclamation method are only limited in one part rather than whole process.Besides,the studies of suspended sediment diffusion in construction process often use the two-dimensional diffusion equation to calculate the envelope area.It can not show the dynamic changes of suspended sediment diffusion visually.This thesis focuses on the analysis of factors which affect the production of suspended sediment in different parts in the process of reclamation and discusses the method of reducing suspended sediment in each part.And it makes quantitative analysis of results difference in different influence factors through comparing the different conditions of suspended sediment concentration and the diffusion range by numerical simulation.The main contents are as follows:1.The analysis of main factors which influence the production of suspended sediment in the construction process of landfill reclamation method.It focuses on the trench excavation,setting and Cofferdam Demolition,reclamation and natural factors which influence the production of suspended sediment in the construction process through the analysis of suspension mechanism of sand production.2.It makes an optimization study of construction technology in reducing suspended sediment.Then,it puts forward the corresponding optimization measures based on the different parts of suspended sediment production in the first one above,including revetment filled position selection riprap construction,excavation stage construction machinery selection,selection of construction sequence and the weather of the cofferdam,fill material selection,drain,reasonable arrangement of the overflow position,Longkou closure machine selection and so on.3.It simulates design conditions and establishes numerical model.The research object is Longkou Bay.It applies Mike21 water power module(HD)coupled convection diffusion module(TR),uses the momentum equation,mass equation and convection diffusion equation,employs mesh generator to generate the triangular unstructured grid,and establishes relative solutions in the area of suspended sediment transport and diffusion model.Then,it uses the above model to calculate the migration dynamic of local tidal current field and analyses the suspended sediment concentration envelope.Moreover,it also employs quantitative analysis to find out the difference of suspended sediment concentration and the diffusion range under different source strength of fill material and working position.Blow filling reclamation method of suspended sediment produces mainly in revetment,trench excavation,cofferdam building and dismantling and filling stage.The production of suspended sediment can be reduced effectively if corresponding optimization measures can be put forward in different construction parts.A strong source,reclaimed materials,and work position has significant effect on suspended sediment concentration and the diffusion range.The conclusion of this thesis can provide a theoretical foundation for the actual construction of the project.