Comparison of Existing Equations for the Design of Crown Walls: Application to the Case Study of Ericeira Breakwater (Portugal)

Abstract

The correct calculation of forces and moments caused by wave action over crown wall structures is critical for their design. There are several existing equations for this, some of which are sanctioned in practice as it is the case for Jensen (1984) and Bradbury et al. (1998), Günback and Gökce (1984), Martin et al. (1999), Berenguer and Baonza (2006), and Pedersen (1996) and Nørgaard et al. (2013). These equations are the main tool for the design of breakwater crown walls and their accuracy is crucial to ensure the stability of the crown wall, especially when considering the sea level rise due to climate change and the possible damage of the armor, since both aspects are not usually considered in most original design studies. In a scenario of climate change, it is very important to estimate the possible changes in security factors due to both these aspects, comparing the results with the original design ones. This paper has as main objective to analyze it for the case study of Ericeira rubble mound breakwater in Portugal. For this, a comparison of the results using those equations and different scenarios including the current, considering sea level rise and armor damage, were performed to extract some conclusions: the increase in the sea level in the case study was not significant and therefore its incidence is very small; and the damage to the main armor by losing pieces at the berm is much more important in this case study, so it is essential to carry out the proper maintenance of the design section. On the other hand, horizontal forces are more conservative using Pedersen and Nørgaard equations, obtaining the lowest value with Martin. Regarding uplift pressures, Martin gives the lowest value, while the most conservative values are given by Günbak and Gökce’s for two scenarios, and Pedersen and Nørgaard for the other two scenarios. Furthermore, the sliding safety coefficient is more conditioning than overturning the safety coefficient in all the scenarios.

Field Campaign on Pressure on the Crown Wall at the Outer Port of Punta Langosteira Breakwater

“…Günback and Gökçe (1984) [11] do not impose validity limits on the equation. However, as referred to in Pereira et al (2021) [21], the geometry considered in all of the formulas has the armour berm below the crest of the crown wall, and here, the crown wall is completely protected by the outer armour composed of cubes, which can lead to more overtopping conditions than with other blocks, which leads to larger wave dissipation.…”

“…Nowadays, these formulas are starting to be applied for a great variety of wave conditions and sea levels [21], some of them out of the limit of the application of equations, which is most important considering the phenomenon of climate change [22][23][24][25][26].…”

Effects of Tidal Stream Energy Exploitation on Estuarine Circulation and Its Seasonal Variability

“…The interest in carbon-free energy sources has increased drastically, resulting to a large extent from the effects of climate change, which have become more evident over the last decades [1,2]. In this context, a large number of policies have been implemented within different legal frameworks in order to achieve more ambitious quotas of renewable energy production [3][4][5][6][7][8].…”

Coastal Engineering: Sustainability and New Technologies

“…In the context of climate it is vital to estimate the possible changes in security factors caused by both of these aspects, comparing the results with those of the original design. Pereira et al [21] compared the forces and moments obtained for different equations in different scenarios, including the current and considering the sea level rise and armor damage, when applied to Ericeira breakwater.…”