两相物质组成对泥石流固相流速特征的影响

固相颗粒流速是研究泥石流冲击力和防治结构荷载取值的关键问题。本文基于水槽模型试验,采用粒子图像测试技术提取了黏性泥石流表面固相颗粒流速,基于两相流模型探讨了浆体黏度、固相体积浓度与颗粒粒径对泥石流固相粗颗粒流速特征的影响。结果表明：泥石流龙头现象随浆体黏度与固相体积浓度增大而减弱；固液相相对运动随浆体黏度增加而减弱,大黏度与小粒径组合条件下消失；固相颗粒流速随浆体黏度与固相体积浓度呈正相关,与颗粒粒径呈负相关。两相物质组成影响固相颗粒间的摩擦力与/或碰撞力、浆体施加的粘滞阻力、拖曳力与虚拟质量力,其对流速的影响还需进一步深入研究。

Effects of the two-phase compositions on the solid-phase velocity of debris flows

The velocity of solid-phase particles of debris flows is a key issue for its kinematics and prevention measures. Flume model testsSand particle image velocimetry were conducted to get the solid-phase velocity of debris flow. Effects of slurry viscosity, volume concentrations and particle sizes on the solid-phase velocity characteristics were accordingly analyzed by adopting two-phase debris flow model. The high-concentrated-particle debris flow head got weak with the increase of slurry viscosity and volume concentration. The relative motion between solid and liquid phase decreased with the increase of slurry viscosity, and it vanished when the volume concentration is big and the particles are small. The solid-phase velocity of debris flow had a positive correlation with the slurry viscosity and volume concentration, and had a negative correlation with the particle size. Two-phase composition of debris flows affect the force of friction and/or collision between solid-phase particles, and the viscous resistance force, the viscous drag force and the virtual mass force acting on particles, which are induced by slurry. The influence of these forces on the solid-phase velocity needs further study.