Do Rock Design Formulas Based on Wave Flume Experiments Reliably Model Their Performance at Sea?

Abstract

The mean sea level rising predicted for this century and the following centuries will make necessary to protect most of the human properties located on the coast. One of the alternatives is the construction of slope breakwaters along hundreds of kilometers of coastline. For coastal engineering this task is a social/environmental and economic/financial challenge, in particular the optimization of the total costs of the structure during its useful life. It is common to design these structures with the Van der Meer stability formula, assuming that the uncertainty of the project is due to maritime agents. Today, this approach is no longer valid and must be reconsidered to adapt to the social and environmental demands. The main source of uncertainty of the Van der Meer formula is epistemic, associated with its ability to predict the progression of failure modes of the structure. This study analyses the actual formula of design coastal structures and discusses the limitations for predicting damage progression, which directly affects designing strategies and total lifetime conservation and repair costs of the structure. It is shown that these limitations derive from: (1) design and experimental technique of the wave flume to propose the formula; (2) non-dimensional variables and parameters included in the formula; and (3) the method of application. It seems desirable and urgent to review and update the state of knowledge and tools for slope breakwater design to meet the demand for protection of human properties on the coast.