The hydraulic stability assessment of the NoFloods Water tubes has been carried out with a retention height from 0m to 1.0 m. We refer to the following relationship between the required friction angle and the height of retained water for recommended retention height.
Relationship between required friction angle and height of retained water
Another way of presenting the results is by determining the safety factor for a given situation. Note that a safety factor below 1 describes an unstable situation and that the higher the safety factor, the higher the safety. The figure below presents the safety factor for four assumed friction angles, namely 20, 25, 30, and 35, which cover the relevant range for the interface friction between PVC and sand.
Safety factor for typical friction angles
As an example, in the case of a friction angle of 25 the safety factor is 1.4 for a height of retained water equal to 0.9m and 1.0 for 1.0m. If the friction angle is higher, e.g., 30, the safety factor is always higher than 1, and the barrier is thus stable in all cases.
In summary, the relationship between the recommended friction angle, safety factor, and height of retained water is crucial in assessing the stability of the Flood Barriers. Higher safety factors and appropriate friction angles contribute to the barrier’s overall stability and safety in various flood scenarios.