Research On Coupling Model Of SPH And Gravel Element Method And Stability Of Wide Shouldered Breakwater

Wide shouldered breakwater is a kind of riprap dike,which is mainly composed of protective block stone and core stone.This type of riprap dike can effectively utilize the various weight classes of rock quarries.Compared with the traditional riprap dike,the most important feature of the wide shouldered breakwater is that it allows the block stone of the protective layer to move unsteadily under the action of waves,which leads to the deformation of the protective layer and finally forms a dynamic equilibrium profile.Wide shouldered breakwater has the advantages of being economical and practical,convenient for construction,convenient for coastline reconstruction,having little impact on the coastline environment,easy to cover vegetation,and creating habitat space for aquatic plants and animals near the shore.In this paper,a model of Gravel Element Method(GEM)is proposed.GEM is a modeling solution method with gravel as a unit.It emphasizes the stress state and overall movement process of gravel,and considers the role of gravel arrangement and contact force transfer in the model.The concept that block stone body is approximate to mechanical ball is put forward.For the irregular block stone,Fourier series is used to expand the boundary contour of the block stone,and the mechanical characteristics of the block stone surface are reflected in the expansion function of periodic change.The method of random filling of mechanical spherical element with gradation distribution in a given dike type is studied.This paper analyzes the stress state of mechanical ball of piled block and stone,and puts forward the concepts of fitting arrangement and grading solution.The transfer method is used to solve the statically indeterminate problem of block and stone,and the virtual displacement principle is introduced to solve the statically indeterminate problem.The analysis of the stable state of pile-up block stone provides a theoretical basis for the establishment of coupling model and the movement of slope block stone under wave action.The flume model test of stacking block and stone was designed and completed.In the process of flume test,two kinds of sloping broad shoulder breakwater sections were designed,and the experimental study of different sets of secondary wave elements acting on the broad shoulder breakwater sections was carried out.The wave height,velocity,pressure and final dynamic balance section were collected,sorted out and analyzed.The wave force acting on the cross section of the wide shouldered breakwater is the main reason for the movement of piled blocks.On the basis of the potential flow function on the slope,the effect of wave breaking on the slope block stone near the static water surface is considered.Combined with the empirical formula,the wave impact velocity in the breaking region is calculated.By adjusting the corresponding parameters,the force on the three-dimensional cylinder of unit length is equivalent to that on the three-dimensional sphere,and the wave force on the slope is verified by combining with the physical model.The wave motion in the pore is equivalent to the internal pore circulation,and the pressure in the pore is determined according to the Forchheimer formula.The coupling model of SPH and GEM is proposed.SPH method was used to simulate the wave motion in the flow field outside the rockfill embankment,the pore circulation was used to simulate the water movement inside the rockfill dike,and GEM was used to simulate the stress state and movement process of the block stones on the wide shouldered breakwater under the action of waves.The changing process from static equilibrium to dynamic equilibrium of wide shouldered breakwater is simulated,and the wave elements and the stable cross section conditions affecting the stability of rock and rock on the wide shouldered breakwater are studied.