Flow Control Of Debris Flow Start And Dredging In Drainage System

Debris flow is a common geological hazard in China, which often brings great loss for peple’s life and production.It has a long history of research on d ebris flow control.It costs much for the debris flow control engineering.Besides, the effective process is longer and can not meet the requirements of disaster re duction.What’s more, the current control measures are mostly for the formation of debris flow control and early warning.Using the method of water separatio n combined with siphon drainage technology, it can quickly discharge excess fl ood seperated from debris flow gully isolated to downstream safety zone throu gh siphon pipe. So it can effectively improve the efficiency and durability of de bris flow control.In this paper, the analysis of the starting mechanism of the water stone fl ow is carried out.it sets up the relationship between the water depth of the uni form flow in dynamic area catchment before loose deposits and the thickness o f sheet-flow layer.The relationship between flow and water deepth in the gully is also established.Analytic analysis takes into account two types of cases.One is that when the bottom width is constant,the longitudinal slope,the form of cross section and the cross slope coefficient will have an impact on water dept h.The other is that it analyzes the relationship between water depth and bottom width as well as cross slope coefficient when taking into account the gully er osion, variable bottom width and flow in the gully. So it may provides theoretic al basis for the further shunt flow control in practical engineering.There is a lot of sediment in the diversion water. Some sediment may be deposited in the pool, thereby making drainage pool lose the drainage capacity. In this paper, a three dimensional numerical model of siphon drainage pool is established.Then it analyzes sediment incipient motion and suspension using the fixed bed model and Euler movable bed model respectively.What’s more,it stud ies the dredging characteristics and influence factors of siphon drainage pool.It shows that uneven bottom bed is conductive to sediment incipient motion and suspension.With increacing head difference between inlet and outlet,it can impr ove the dredging efficiency of siphon drainage pool.The interaction between se diment and water as well as the interaction between sediment consumes the en ergy, which will affect the flow velocity.Combined with the analysis results of numerical simulation, it is suggested that the water head difference between i nlet and outlet should be above 5m, and the diameter of the barrier grid be n o more than 10mm.This can guide the design of siphon drainage pool in debri s flow prevention engineering.