Xbase®
DMC had developed a new toe concept which combines easy placement and high stability. One of the most critical factors involving the design of a breakwater is the design of the toe. Toe design can be even more complicated in depth limited seas which give unpredictable high hydraulic loads on the toe armour. Furthermore extreme swell conditions complicate the placement of the toe.
Download the paper: Xbase® development and application of a special concrete toe unit for extreme conditions presented at Coastal Structures Venice 2007.
Model tests
Model tests were performed to test the stability of the toe of a breakwater at Swakopmund Namibia. Depth limited wave conditions and extreme swell conditions were critical factors for the toe stability at that location. Different conventional toe options were tested and proved to be unstable, until the idea came up to remove one of the noses of the Xbloc®.
These modified Xblocs, the Xbase® units have a low centre of gravity and are not sensitive to overturning. Because of their flat base they are easy to place on the base layer. Other single layer armour units tend to roll away from their intended position when placed on a rock layer.
Advantages of Xbase toe unit
- High hydraulic resistance
- Low centre of gravity
- Easy casting
- Easy placement
Advantages compared to conventional rock toe
- Higher stability
- Lower use of rock material
- Easier and faster to construct
Xbase® units can also be applied as first row of armour units on a quarry run filter layer for sandy seabeds. Project specific tests have been carried out on this solution at the Danish Hydraulic Institute.
Xbase crest elements
Xbase® units can also be applied as crest units on wide rubble mound crests. This solution was tested at CSIR, and has been applied for the breakwater rehabilitation at Port of Poti.
Xbase® crest units are easy to place. Due to their low cente of gravity they have a high hydraulic stability, and are not susceptible to rocking.
