PONTA DELGADA BREAKWATER REHABILITATION RISK ASSESSMENT WITH RESPECT TO BREAKAGE OF ARMOR UNITS

H. Ligteringen, J.C. van der Lem, F. Silveira Ramos

Abstract


The outer portion of the Ponta Delgada Breakwater in the Azores was constructed in the sixties, applying an armour layer of 25 t Tetrapods on a slope of 3 in 4. After two decades of recurring damage and repairs, a redesign and rehabilitation were undertaken. An armour layer of 40 t Tetrapods on a slope 1 in 2 proved to meet the more severe design wave conditions established for the rehabilitation. This was the most attractive solution from cost and constructability viewpoint. To check the risk of breakage of these units under design conditions, the rocking was analysed both in hydraulic model and by means of an analytical simulation program. This allows to assess the actual impact velocities of rocking units and the percentage breakage under given wave conditions.

Keywords


breakwater; breakwater rehabilitation; armor; armor units; risk assessment

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