Evaluation of the Factors Affecting the Hydraulic Stability of Tblock™ Coastal Protection Armour Unit

A new regularly placed interlocking block, named Tblock™, is developed to be used as single layer armour for breakwaters and coastal protection. The stability of Tblock™ is achieved through its weight, interlocking and friction. Its design aims to provide simplicity in both placement and moulding. Tblock™ is designed to be placed on a 3V:4H slope. The stability of Tblock™ was tested through 2D physical modelling experiments in a wave flume at the UNICAEN, France. The effect of using different armour porosities, toe designs and core material size on stability was investigated in six tests. The results indicate that the Tblock™ demonstrated a high stability number \(\left( {N_{\text{s}} = 4.75} \right)\) $\left(N_{\text{s}}=4.75\right)$ when using recommended packing density and a rock toe. It was noted that the phenomenon of group uplift occurred during the experiments with the highest packing density or when a fixed beam was used as a toe. Considering group uplift as a new criterion for the start of damage, the stability number in these cases drops to 2.43. The occurrence of group uplift highlights the importance of the minimum porosity within the armour layer, rather than the overall porosity of the armour layer and proper toe design in the regularly placed interlocking blocks.