HYDRAULIC TRANSPORT OF COARSE GRAVEL-A LABORATORY INVESTIGATION INTO FLOW RESISTANCE

摘要

Flow resistance relating to the hydraulic transport of solids has attracted much attention from the dredging industry and related academic fields. Until now, a great deal of literature on the flow resistance of sand or fine particles hydraulically transported in a pipeline has been published. However, very little research on the hydraulic transport of coarse particles has been carried out, resulting in very limited understanding about the behavior of coarse particles. In recent years the hydraulic transport of coarse gravel or stone pieces has played an important role in the production control of several dredging projects in China. In order to investigate the basic characteristics of big particle transport, a series of laboratory tests were performed on the 315kW-DN200mm slurry pump-pipeline stand at Hohai University, China. Three types of gravel with diameters of 4.0～8.0mm, 8.0～16.0mm and 16.0～32.0mm were used. The delivered volume concentrations were controlled around 6～7% and 10～12%, respectively, forming gravel-water mixtures with specific densities of 1.1 and 1.2. Laboratory tests show that the behavior of the coarse gravel hydraulic transport differs somewhat from that of fine particles. The characteristics of flow resistance for the hydraulic transport of coarse gravel and the factors that affect the resistance are discussed in this paper. An empirical prediction model for this flow resistance is also presented.