REVISITED HYDRAULIC FUNCTIONING OF PERMEABLE PILE GROINS

Since 1965, a new type of permeable groins (or ‘pile screens’ referred to Bakker et al.,(1984)), which consist of wooden pile rows with a high permeability, have been widely used to protect the coastline from recession in the Netherlands, especially at southwestern coastline. However, the hydraulic functioning of such structures has not been understood well compared to traditional impermeable pebble mound groins. As the wooden pile groins become older and the maintenance costs increase, the issue of their effectiveness has become of importance, while no serious research has been undertaken. This paper tries to tackle this issue. Based on experimental data which was obtained at Delft Hydraulics (Hulsbergen and Horst, 1973), the functioning of pile groins has been revisited and analyzed by an advanced numerical model. The simulations give deeper insights into the effectiveness of permeable pile groins under well controlled laboratory conditions.