Study On Flow Characteristics Of Concrete In Pumping Pipeline Based On Fluid-Solid Coupling Simulation

Concrete pump trucks have become the preferred machinery for placing concrete in low-and medium-rise building construction,and their fresh concrete pumping technology is the key to successful concrete placement.However,in the process of concrete pumping,some unfavorable pumping phenomena often occur,such as concrete segregation,water secretion and pipe blockage.Once these phenomena occur,they may lead to concrete pumping failure.Therefore,it is necessary to study the flow characteristics of concrete in the conveying pipe and the process of concrete pumping.The traditional experimental methods have problems such as complicated experimental process,long period and consuming a lot of resources.In this paper,the flow field characteristics of C30 fresh concrete in the pumping process are studied by two simulation methods: discrete element method(DEM)and computer fluid dynamics combined with discrete element method(CFD-DEM),and the main research contents are as follows:(1)A simulation model of pump elbow based on the Discrete Element Method(DEM)is established,and the Hertz-Mindlin with JKR particle contact model is developed by considering the characteristics of fresh concrete.The particle model is validated using slump tests.The EDEM software is utilized to perform numerical simulations using the established particle model to analyze the influence of different factors on the flow characteristics of fresh concrete during the pumping process.(2)A pumping model of fresh concrete is established using the CFD-DEM coupling method.The flow behavior of fresh concrete during the pumping process is studied through the coupling of EDEM and Fluent software.The flow characteristics of fresh concrete under different influencing factors,including pipe diameter,curvature radius,size and shape of coarse aggregates,and pumping speed,are analyzed.The simulation results of the two methods are compared with actual engineering data,and the more accurate simulation method is selected for subsequent wear studies.(3)A wear model of pump elbow based on Archard wear is established to systematically analyze the effects of elbow diameter,curvature radius,coarse aggregate size,shape,and pumping speed on elbow wear.The analysis results are used to optimize the pumping conditions of fresh concrete and improve pumping efficiency.