Research On The Numerical Simulation Of Hydraulic Characteristics And Emergency Technique Of Dike Closure

Dike is a kind of water retaining structure to prevent the flood overtopping or storm.Over the years,always accompanied by major disaster,the dike burst danger happening seriously affected the people's production and life.Especially in recent years,with extreme weather occurring frequently,such as continuous heavy rain,there was flood disaster by dike breach in the case of river upstream water under strict control.After the flooding,sealing the dike breach rapidly to reduce loss has real demand and engineering significance.Under this premise,this article selects the actual terrain of a typical dike section of Heilongjiang river and carrys out the three-dimensional numerical simulation on the hydraulic characteristics of the dike closure construction.Then it puts forward the rapid sealing technology for the sand dike of the main stream of Heilongjiang river and carries on the research of the closure construction transportation system simulation.Taking Bacha section of Tongfu dike of Heilongjiang river as the research object,CATIA software is used as the three-dimensional modeling platform to establish three-dimensional river channel terrain and dike solid model.The basic theory of numerical simulation of water flow is analyzed,and RNG K-? turbulence model,finite difference discrete method,Tru-VOF free surface treatment method and implicit GMRES pressure velocity solution are selected according to the characteristics of the problem.FLOW-3D software is used to carry out the three-dimensional numerical simulation for the dike burst flow with actual topography,and seven kinds of entrance width(300m,200m,100m,60m,40m,20m,10m)for closure work process and two water conditions of the inner dike(3m or 2m lower than one hundred years flood level)was selected.The hydraulic parameters and the changing trend of the entrance area are obtained under different entrance width and different inner water level of the dike.Based on the analysis of the characteristics of the traditional dike closure technique and the new material or technique,the numerical simulation results and the related engineering examples,this paper puts forward the emergency technique program for sealing the sand dike of the main stream of Heilongjiang river under extreme flood conditions:the technical scheme for protecting residual dike including the use of long-tube bag on the upstream wrapped head and the use of the improving traditional method on the downstream wrapped head;throwing 0.2m?0.4m stone and then throwing iron chestnut on the bottom before occupation construction for protecting the bottom;using block stone two-way closure,and in the occupation of the high hydraulics index section,using the occupying and closure technical scheme of "Throwing large pieces of stone and reinforced stone cage on the upstream-side toe and the downstream-side toe of the dike head,followed by block stone threw on the middle of the dike head".These can provide reference for actual projects.Aiming at the emergency technical scheme of dike closure,the corresponding closure construction transportation system simulation research is carried out.Based on the simulation model and method,the reference value of the average throwing strength and the utilization rate of the mechanical equipment under the condition of different mechanical equipment is calculated,and the influence degree of the number of various machinery on the evaluation index is analyzed.The results show that when the number of loaders is constant,the increase of the number of dump trucks in a certain range can greatly improve the average throwing strength of dike head,the utilization rate of the loaders and the utilization rate of the discharge point of the dike head.When the number of dump trucks is constant,increasing the number of loaders has little effect on improving the average throwing strength.The influence of the number of discharge points on the average throwing strength of the embankment increases with the increase of the number of dump trucks.Considering the above,the dike head only allows two dump trucks to unload at the same time.