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...

Flexible scour protection around cylindrical piles

This research focuses on the behaviour of a granular scour protection around piles when the bed is subjected to bed degradation. Furthermore, engineering guidelines are provided to account for bed degradation in the design of the initial scour protection. To address the behaviour of the protection, a physical model is used and to obtain the...

Falling aprons

Falling aprons do not always behave as expected, e.g.: sometimes they are not launched. The reasons behind this are unknown what has to do also with the not well-known failure mechanisms responsible for correct functioning of falling aprons. In that respect it is significant that the design rules are based on geometrical considerations....

Durban Harbour Entrance: Widening and Deepening Project

The Durban Harbour, run by the National Ports Authority of South Africa (NPA), is the largest harbour in South Africa. To stay competing in the 21st century the harbour entrance must be widened and deepened for the entry of Post Panamax ships. An important part of the Durban Harbour entrance Widening and Deepening project is the demolition of...

A new view on falling aprons

In a flume of BallastHam Dredging a falling apron model has been constructed and loaded by current. The tests have been done with different rock sizes, different layer thickness of the top storage of the apron and two different gradings. In summary it was found that for both the narrow graded rock layers as well as for wide graded riprap the...

A study of the behaviour of and the forces in a bed protecting mattress: The falling apron

In many cases the bottom around a structure that is exposed to current has to be protected by a mattress. The purpose of the mattress is to protect the soil besides the structure from erosion and scour, thus preserving the strength of the foundation of the structure. Examples are the bottom protection around bridge piers, along guide bunds and...

Water en bodem standzeker (Moderne rivierkunde)

In deze publicatie worden enkele resultaten van projecten in Bangladesh gepresenteerd met aandacht voor een mogelijke toepassing in alternatieve ontwerpen van kribben. Deze resultaten betreffen hoofdzakelijk doorlatende palenrijen en falling aprons. Een falling apron kan worden vergeleken met een toplaag zonder zinkstuk.