Author(s): Jorge Molines Llodra; Sergio Lozano; Patricia Mares-Nasarre; M. Esther Gomez-Martin; Josep R. Medina

Linked Author(s): M. Esther Gomez-Martin

Keywords: Cubipod; Green infrastructure; Homogeneous low crested structure; Wave transmission; Coral reef

Abstract: Homogeneous Low Crested Structures (HLCS) with pre-cast concrete units are a new coastal structure to protect beaches from wave attack. HLCS are a green infrastructure which can be used to restore degraded coral reefs areas where not only the coastal protection is important but also the regeneration of coral reefs. The placement grid of HLCS plays a relevant role on their hydraulic performance affecting the wave transmission and hydraulic stability. Within the Project HOLOBREAK, 5-layer Cubipod HLCS trunks with cotα=2:1 were tested in the wave flume of the Laboratory of Ports and Coasts (30 x 1.2 x 1.2 m) at the Universitat Politècnica de València. The 5-layer Cubipod HLCS was constructed following a triangular equilateral placement grid with porosity p[%]=50 on a 4% bottom slope. The model showed a total height around 20 cm with Cubipods with nominal diameter Dn[cm]=5.17. In total, 100 tests were carried out with four wave steepnesses (s0p=0.01, 0.02, 0.03 and 0.04) and four crest freeboards (Rc[cm]=-3, 0, 5, 10 cm). The tests measured the layer thickness, armor stability, wave reflection and wave transmission of the structure. The wave height (Hm0) and wave period (Tp) at the toe of the structure were obtained using the SwanOne model. In order to eliminate the influence of the changes on the crest freeboard during the tests, only the tests before Initiation of Damage were used to estimate the transmission coefficient of 5-layer Cubipod HLCS (around 45 tests). Existing formulas to estimate wave transmission on Low Crest Structures such as d’Angremond et al. (1996) and the only formula to estimate the wave transmission on HLCS (Medina et al., 2019) did not provide accurate predictions due to the differences on the structure geometry or the range of application. In this study, Neural Network models are used to create a new wave transmission estimator valid for 5-layer Cubipod HLCS with R2=0.91 within the ranges -2.0≤Rc/Hm0≤3.6 and 0.008≤s0p≤0.035 (Lozano, 2021). REFERENCES d'Angremond, K., Van der Meer, J.W., De Jong, R.J. 1996. Wave transmission at low-crested structures. Proc. 25th Int. Conference on Coastal Engineering, ASCE, Orlando (Florida), Vol 3., 2418-2527. Lozano, S., 2021. Estudio de transmisión de oleaje para el diseño de diques arrecife homogéneos de Cubípodos. Aplicación a la protección del litoral del Parque Nacional Corcovado (Costa Rica). Master Thesis, School of Civil Engineering, Universitat Politècnica de València, Valencia. Medina, J.R., Gómez-Martín, M.E., Mares-Nasarre, P., Odériz, I., Mendoza, E., Silva, R., 2019. Hydraulic performance of homogeneous low-crested structures, Proc. of the Coastal Structures Conference 2019, Bundesanstalt für Wasserbau (BAW), Karlsruhe (GE), 60-68.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022757

Year: 2022