基于数值模拟的新拌混凝土竖直泵送流动行为

借助数值模拟研究了3种流动性的混凝土在竖直向上泵送时的管内流动行为，分析了混凝土内部压力和流速的分布规律.结果表明：泵送压力主要受润滑层性质的影响，其纵向分布与管壁阻力沿程变化规律有关，截面中心的泵送压力略高于管壁处；混凝土在管内的流动存在“前进—扩散—滞留堆积—汇聚”的行为特征，并据此分析了润滑层的形成和粗骨料的迁移，解释了泵送离析和堵管的原因.

Numerical Simulation on Vertical Pumping Flow Behavior of Fresh Concrete

To examine the pumping flow behavior of fresh concrete in vertical upward pumping， the flow of three concretes with different fluidities in a vertical pipeline was investigated by numerical simulation. The distribution of pressure and velocity field in concrete during pumping were analyzed in detail. The results show that the magnitude of pumping pressure is mainly affected by the properties of the lubrication layer. The longitudinal pressure distribution is related to the pattern of boundary resistance variations along the pipe wall， while the pressure at cross-section center is marginally higher than that at the pipe wall. Moreover， the research identified the flow behavior of concrete in the pipe， involving progression， diffusion， retention， accumulation， and convergence. Based on this， an analysis was conducted to understand the formation of the lubrication layer and the migration of coarse aggregates. These findings explained the reasons for concrete pumping segregation and plugging.