Analysis Between Beach Erosion-deposition Deformation And Influence Factors Under Solitary Wave

There is rich mineral resource on the coast which has great value in the environment and economy.However,the deposition problems of the port,estuary,lagoon and gulf's mouth have serious impact on the construction of coastal engineering.In addition,it is getting worse of coastal erosion phenomena because of the rising sea level and a variety of intervention of human activities.So,it is of great significance for the research about beach erosion-deposition deformation.With huge energy,waves produce a great impact on the shores or structures,which are the main factors of the change of the coast.Sediment Incipient motion and sediment transport not only depend on the hydrodynamic condition but also the bed material gradation.Many scholars carried out research on related problems,but the quantitative relationship between beach erosion-deposition deformation and the influence factors was hardly discussed.Due to the actual ocean waves of coastal sea area equivalent to solitary wave,the research between beach erosion-deposition deformation and influence factors under solitary wave has been carried out by physical model and numerical calculation.In addition,the sediment trajection and scouring-depositing mechanism have also been explored.This paper is mainly consists of two parts.The first part is the study of beach erosiondeposition deformation at the action of solitary wave.The second part is the analysis of dynamic characteristics of water and scouring-depositing mechanism.The main research results as follows:?1?The beach profile gradually develops from the erosion type to transitional type with the increase of sediment grain size.With the further increase of sediment particle size,it occurs that transitional beach profile turns to be deposition type.The wave height mainly affects the size and positon of sandbank and sandpit,which is closely related to the sediment particle size.Based on a large number of experimental data,the relation between beach profile shapes and wave steepness H L,the relative strength of wave acting on sedimentgH w is established,which mainly include maximum deposition height Maxd_deposition/d₅₀,maximum scour Maxd_{deptherosiond}/d₅₀,the distance from the dam crest to offshore L_{depositionmax}-SL/d₅₀ and the distance from the pit bottom to offshore L_erosionmax-SL/d₍50.?2?On coarse and uniform beach,the sediments near the coastline mainly are deposited on the jump region.A part of sediments on the breaker region are deposited near the positon of maximum wave runup height,and the others primarily form sediment body near the coastline.The sediments on breaker-climbing zone take on uniform distribution in the whole area at the action of solitary wave.On wide grading and non-uniform beach,a part of coarse sediments and fine sediments are deposited near the positon of maximum wave runup height,and some deposit on the jump region close to the deep water area.The fine sediments mainly mainly locates in the lower.The Coarser sediment particles are silted near the positon of maximum wave runup height,and some deposit near the coastline.?3?The beach scouring-depositing patterns are determined by transportability ratio of wave runup and wave backwash.On breaker-climbing zone,the time-average velocity of wave backwash is greater than wave runup,the local scour hole is easily formed.In coastal sea area,the time-average velocity of wave backwash is significantly less than wave runup,the sediment body is easily formed with larger.sediment grain size.