Geometrically Open Inverted Granular Filters

This study investigates the use of an open filter in a land reclamation structure. The possibility of replacing the geotextile that secures the core-backfill interface with a granular filter has been investigated. This is easier to install and therefore a potential cost-saving. Experiments have been done to determine the influence of various...

Inversed Open Granular Filters in Land Reclamation Structures: Modeling of the Interface Stability

This thesis is the third study of a research line that focuses on the interface stability of a rubble mound sand retaining structure. The type of interface considered is a geometrically open granular filter because of its economical and constructional benefits. The stability of an open filter structure in which the base layer is located on top...

Stability of open granular filters under wave loading

A filter can be applied to protect a bed against scour. Normally, these filters are geometrically closed, to prevent winnowing of the base material through the filter. However, geometrically closed filters are expensive and difficult to realize in the field. Geometrically open filters can serve as an alternative. Within an open filter, the pores...

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...

Scour below the toe of breakwaters: Investigation of scour formation through a geometrically open filter configuration located at the toe of a rubble mound breakwater lying upon sand

Scour formation at the toe of a rubble mound breakwater can lead to abrupt failure. Nowadays, counteraction of scour via geometrically closed filter rules, geotextiles or combinations is the common practice. Alternatively, in specific cases the use of geometrically open filters can save significant amount of time and decrease constructional...

Stability of open filter structures

Granular filters are used for protection against scour and erosion. For a proper functioning it is necessary that 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 the filter, and...

Interface stability of granular filter structures: Desk study

A desk study has been carried out regarding interface stability of granular filter structures. Actually, the project focuses on two particular aspects: (1) interface stability as function of the thickness of the filter layer consisting of standard armourstone gradings, and (2) interface stability of gravel mixtures with a wide gradation The...

Open filters in breakwaters with a sand core: Study into the stability of granular geometrically open, hydraulically sand-open filters in breakwaters with a sand core

Thesis study into an alternative design for breakwaters made of granular materials like sand and quarry stone. In this design, the breakwater is constructed of a sand core and a layer of large stones directly on top of it, without the traditional filter layers in-between. The single layer of stones serves as one open filter layer that has to...

Shear stress concept in granular filters

Scour is a natural phenomenon caused by the flow of water in rivers and streams and occurs as a part of the morphological changes caused by rivers or as a result of man-made structures. For the Dutch Delta Works hydraulic structures were often constructed on fines with loose packing. To guarantee the geotechnical stability of these structures...

Imperfecte filterconstructies onder golfbrekers

Filterconstructies worden toegepast onder de teen en armour layer van uit breuksteen opgebouwde golfbrekers. Daarnaast worden zij vaak, als onderdeel van een bodembescherming, aangebracht op de zeebodem veer de teen van de golfbreker. Filterconstructies hebben als doel erosie van het onderliggende basismateriaal te voorkomen. Geometrisch-dichte...

Erosie onder een geometrisch open filter

Deze notitie beschrijft de resultaten van een inleidend onderzoek naar de mechanismen van de erosie van de basislaag onder geometrisch open filters. Hierbij wordt in eerste instantie uitgegaan van de beter onderzochte erosie van de bodem van een waterloop zonder beschermende filterlaag. Op basis van metingen van Van Os (1998) in een inleidend...

Hydraulische belasting op een geometrisch open filterconstructie

In de kust- en waterbouw worden regelmatig geometrisch open filterconstructies toegepast. Er bestaat onduidelijkheid over het doordringen van de hydraulische be lasting in de filterlaag en de invloed daarvan op de erosie van de basislaag. Eerder onderzoek geeft het verband aan tussen de schuifspanning op de filterlaag en schuifspanning op de...

Probabilistische analyse van onzekerheden bij ontwerp en uitvoering van een enkellaagse geometrisch open filterconstructie in een open waterloop

In dit rapport worden de resultaten beschreven van een onderzoek naar de invloed van de diverse bij het ontwerp en de uitvoering van een enkellaagse geometrisch open filterconstructie aanwezige onzekerheden op de faalkans van de toplaag en de basislaag van de uiteindelijk gerealiseerde filterconstructie. De constructie bevindt zich hierbij in...