Hydraulic stability and wave overtopping characteristics of Tblock™ armour units on a 3V:4H slope

Tblock™ is a newly developed single-layer regularly placed interlocking concrete block that has been designed to work on breakwaters and revetments. Physical model tests were conducted to assess the hydraulic stability and overtopping of the armour layer under a wide range of wave steepness on a 3V:4H slope. Based on 51 stability tests, it was observed that the stability of the Tblock™ armour layer decreases as wave steepness increases. This pattern resembles the behavior of Tetrapod and Cube armour layers. Furthermore, an extreme case of brittle destruction was observed, where the failure occurred rapidly after the extraction of the first unit. When compared with other interlocking armour units , Tblock™ demonstrated higher stability number ( N s ) across a wide range of wave steepness. Based on 27 tests, overtopping performance was unsatisfactory, with a roughness coefficient ( γ f ) of 0.73. Moreover, it was confirmed that increasing wave steepness also reduces the roughness effect of the armour layer. The reflection coefficient was found to be comparable to that of other concrete armour units. • The Tblock™ is a new interlocking, regularly placed armor unit developed for placement on a 3V:4H slope. • Tblock™ armour layer with a 0.57 packing density shows equal or superior stability ( N s ) to similar units across a wide range of wave steepness. • Overtopping performance was subpar with a roughness coefficient ( γ f ) of 0.73. • It was observed that the roughness coefficient ( γ f ) increases with wave steepness.