Publisher's Synopsis
This book contains chapter 4.2 from the main book "Dredging Technology Book 1"One of the most striking phenomena when suctioning a deep suction pit in the sand bottom is the appearance of a steep slowly moving benches producing loose sand that flows towards the suction mouth. This process is called "Breaching". Another amazing phenomenon when breaching is active is the occurrence of very flat (5-20°) banks along which the sand water mixture, that comes from these breaches, flows towards the suction mouth over hundreds of meters distances. Using these two phenomena makes it possible to suck up, from a stationary position, enormous amounts of sand.The reason behind the breaches is the phenomenon called: "Dilatancy" The erosive action of a sand water mixture that runs down on a gentle slope is described together with the at the same time active sedimentation of sand. Erosion is also the basis of the erosive sand production process of a drag head using high speed waterjets with jet water velocities up to 30 m/s and more. The book covers the research results for this high speed erosion of sand. A high speed erosion formula is described which can be used for the development of a calculation model for the sand production of a high speed water jet.
