by Van der Schrieck
Understanding the world of sand and water
This book is derived from chapter 5.2 from the book 'Dredging Technology Book 1'. In order to keep track of things all section and formula numbers are kept the same and start with number 5.
The book gives a comprehensive review of the large scale centrifugal dredge pump tests performed by Professor Kazanzky in Germany Hannover. He ran a lot of tests and compared the results with the well known formulas from Durand-Gibert, Juffin-Lopatin and Fuhrboter in large graphs.
A qualitative description is given of the soil-water mixture flow through a pipeline. The pressure-flow characteristic of a pipeline is explained and the influence of the grain properties such as the fall velocity. The book explains the 3 concentration definitions: Volumetric - , Transport – and the Apparent-concentration. The effect of the viscosity of the fluid and the nature of the soil is discussed. Depending on transport velocity there can be homogeneous mixtures with turbulent or laminar flow. Examples are given such as Newtonian or Bingham fluids. Also heterogeneous mixtures with turbulent flow are described and explained.
A special item is covered being the reducing effect on the pipeline resistance caused by the fine fraction of the solids in the mixture. This has also a reducing effect on the costs of the hydraulic transport and because of that a lack of fines which could not be anticipated for based on the project Tender Documents could be a reason for a claim.
The book ends with explaining the two layer model for pipeline resistance by Wilson and the expansion of this theory by Matousek in his thesis in 1997 at Delft University.