Damage Evolution in Physical Scale Model Tests of a Stretch of the Breakwater of Peniche Harbour.

Abstract

During physical scale model tests of rubble mound breakwaters, the assessment of the eroded volume of the armour layer subjected to incident sea waves can be determined from consecutive surveys of the surface of the armour layer after each test run. This enables one to assess the damage level of the struc ture by comparing erosion profiles and by the eroded volume between consecutive surveys of the tested section. The present study aimed to evaluate the damage evolu tion of a section of the Peniche harbour west breakwater, whose armour layer is made of tetrapods, A dimensionless damage parameter was computed, based on the eroded volume at the end of each test. The test program consisted of three test series (A, B and C) with different durations and wave conditions sequences, considering the low-water level (water depth of 0.20 m at the toe of the structure) and high-water level (0.24 m) and sea states with peak periods Tp = 1.70 s and Tp = 1.98 s and significant wave heights, Hm0, ranging between 0.12 m and 0.19 m. The model was built and operated according to Froude’s similarity law, with a geometrical scale of 1:50. The eroded volume assessment was done by means of armour layer surveys based on the Time of Flight (ToF) methodology, using a Kinect sensor position. The surveys produced 3D surface models, at the beginning and the end of the test series, when the whole extension of the armour layer was dry and visible, and after each intermediate test, when part of the armour layer was submerged. A comparative analysis was made, based upon the damage level obtained with the three different test series (with different durations and wave conditions sequences).