基于动床模型的泥石流虹吸排水分流池自清淤能力研究

泥石流的形成，必须同时具备丰富的松散堆积物、足够的水源和有利的地形地貌3个基本条件.控制调节水动力条件是防止泥石流灾害发生的有效方法，而采用具有自清淤能力的水石分离虹吸排水技术，将分流进入泥石流沟内的水直接排入下游安全区，从而达到减小泥石流沟谷的水动力、防止泥石流启动的目的.而保证泥石流治理效率和耐久性的前提是分流池的自清淤能力.应用计算流体力学软件CFD建立三维数值模型，采用欧拉动床模型对分流池在虹吸作用下的水力特性进行分析，并用物理模型模拟验证了虹吸排水清淤的可行性.分析结果表明：床面不平整有利于泥沙起动悬浮；进出口水头差、泥沙粒径及淤积厚度、泥沙之间的碰撞都会对虹吸清淤效率产生影响.所得结论对实际泥石流防治工程中虹吸分流池的设计，如负压水头、拦污格栅孔径的选取具有一定的指导意义.

Analysis on the self-dredging capability of siphon drainage pool of debris flow based on the movable bed model

The occuring of debris flow in the valley involves concurrently three basic conditions which include rich loose deposits ,enough water and favorable terrain.Controlling hydrodynamic condition is an effective method to prevent the occurrence of debris flow. The siphon drainage technology of self-dredging ability and water separation can discharge excess water from debris flow gully to downstream security zone so as to weaken hydrodynamic conditions in the debris flow gully, hence preventing the occurrence of debris flow .However,self-dredging capability of siphon drainage pool is the premise to ensure the efficiency and durability of debris flow control. By using computational fluid dynamics software CFD together with Euler movable bed model, a three-dimensional numerical model is established to analyze the hydraulic characteristics of the flow in the drainage pool. Mathematical model of sediment incipient motion and suspension is established at the same time. Furthermore,it verifies the feasibility of siphon dredging by employing the physical model. Results show that uneven bottom bed is conductive to sediment incipient motion and suspension. While the water head having difference between inlet and outlet , particle size , deposition thickness and mutual collision between sediment particles all can affect the siphon dredging efficiency. The above results can guide the design of siphon drainage pool in practical debris flow prevention engineering,such as how to choose the water head having difference between inlet and outlet,and the diameter of the barrier grid.