泥石流固液分相流速计算方法研究

Research on Method to Calculate Velocities of Solid Phase and Liquid Phase in Debris Flow

泥石流固液分相流速是泥石流对岸坡、防治结构冲击、磨损机理的核心问题.将泥石流体简化为具有相同粒径的固相和具有相同力学性质的液相,基于泥石流体为沿流动方向的一维两相流体,运用两相流理论建立了泥石流固液分相流速控制方程.构建了泥石流平均压力、彻体力及平均表面力的计算方法,尤其通过浆体的Binhanm体流变方程、Bagnold颗粒相互作用试验成果建立了控制体平均表面力计算方法;建立了固液两相流速比例系数,以及理论固相流速与实际流速的比例系数.据此求解控制方程得到了固液分相流速计算方法,该方法既可同时适用于粘性泥石流和稀性泥石流,也可在泥石流爆发以后通过现场采集沉积物分析反求泥石流爆发期间的分相流速.工程实例分析显示,该方法计算结果与实测结果吻合较好.

Velocity of solid phase and liquid phase in debris flow are one key problem to research on impact and abrasion mechanism of banks and control structures under action of debris flow. Debris flow was simplified two-phase liquid composed of solid phase with the same diameter particles and liquid phase with the same mechanical features. Assuming debris flow is one dimension two-phase liquid moving to one direction, then general equations of velocities of solid phase and liquid phase were founded in two-phase theory. Methods to calculate average pressures, volume forces and surface forces of debris flow control volume were established. Especially, surface forces were ascertained nsing Bingham＇ s rheology equation of liquid phase and Bagnold＇s testing results about interaction between particles of solid phase. Proportional coefficient of velodties between liquid phase and solid phase was put forwarded, meanwhile, divergent coefficient between theoretical velocity and real velocity of solid phase was provided too. To state succinctly before, method to calculate velodties of solid phase and liquid phase was obtained through solution to general equations. The method is suitable for both viscous debris flow and thin debris flow. Additionally, velocities every phase can be identified through analyzing deposits in-situ after occurring of debris flow. It is obvious from engineering case that in the method it is consistent to that in real-time field observation.