Validation and Optimization of a Design Formula for Stable Geometrically Open Filter Structures

Granular filters are used for protection against scour and erosion of base material. For a proper functioning it is necessary that at the interfaces between the filter structure, the subsoil and the water flowing above the filter structure no material will be transported. Different types of granular filters can be distinguished, this paper...

Falling aprons at circular piers under currents

Traditional guidelines on rock protection at circular piers predominantly focus on preventing shear failure (by choosing a sufficiently large rock size), winnowing failure (by designing an appropriate filter) and edge failure (by selecting a sufficient extent). In particular areas (e.g. in an eroding river channel or in an area with large-scale...

Interface stability of granular filter structures under currents

Granular filters are used for protection of structures against scour and erosion. For a proper functioning it is necessary that the interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil material through the filter to the water above...

Report on measurements: Pressure and velocity fluctuations around a granular-bed element

The second chapter describes the general methodology of the research. It presents the key questions about the entrainment of stones from granular filters that are as yet unanswered. It also describes the aspects that are being regarded in the analysis in this report. In chapter 3 the measuring set-up is described. The following two chapters...

Stability of stones in the top layer of a granular filter: Literature survey

In order to understand the processes involved in damaging a granular filter, the behaviour of the separate particles it is made of must be known. The hydrodynamic forces on the particles are very important for understanding this behaviour. These forces have been examined by many researchers. Chapter 2 deals with that aspect. The characteristics...

Design criteria for placed block revetments and granular filters

Design criteria for the coverlayer and filter layer of a placed block revetment are presented. These design criteria were derived on the basis of large scale model tests on revetments and test on granular filters. It is shown that the hydraulic loading in the filter can be described with equations of quasi-stationary flow. General filter...