Recent Question/Assignment

1) Marine Infrastructure and Port Design (10%)
Assume that a recent earthquake has destroyed the existing deep water port located on a Pacific Island and only a small port which can take up to 10 m draft vessel has survived. This port is the lifeline to the country. It is expected that between 200,000 to 600,000 TEUs of cargo will be imported over the next 10 years for the reconstruction effort. Cargo would be coming from different countries in various quantities and will need to be transhipped to the aforementioned island from a larger neighbouring port. Port Relief which is strategically located in relation to the main trade routes in a neighbouring country has been selected for transhipping cargo to the aforementioned island. You are the Port Engineer of Port Relief and you are called to assess the situation and make recommendations for upgrading the existing 20 year old deepwater wharf to cater for mother ships of 5000 to 7500 TEUs capacity for transhipping containers to the country. For transhipment it is intended that 1500 - 2000 TEU capacity daughter ships would be used because of the draft limitations in that country. The existing wharf is only 150 m and it is expected that this will be adequate for meeting the requirement in that country. The existing wharf structure is in need of substantial remedial works but needs to be assessed and strengthened for the larger vessels. In addition the fender system will need to be changed to handle the larger vessels and the smaller range of vessels. You have to assess the size and quantity of fenders that will need to be pre-ordered because of the long lead time for delivery.
• You need to prepare a Brief for consultants to investigate the condition of the structure and to come up with the most cost effective option for the rehabilitation and upgrade of the structure to meet the needs for the next 20 years. (Hint - refer to lectures on durability, lifecycle and corrosion protection)
2) Marinas (10%)
A marina site in a busy harbour is protected from swell waves but is exposed to significant wind waves from one direction, with the following characteristics:
50 yr average return interval: H = 0.9 m, T = 3 s
1 yr average return interval: H = 0.6 m, T = 2.5 s
Using the information given in the lecture notes, select a suitable configuration for a floating breakwater to achieve a ‘good’ wave climate within the marina. Comment on vessel orientation within the marina. What other types of waves should also be considered?
3) Coastal Processes and Modelling (5%)
Different formulae for longshore sediment transport were provided in the lectures. Why is the “Queens” formula considered a better formulation than other formulas? Illustrate the importance of wave period by using the Queens formula to calculate sediment transport for two wave period scenarios of 4 seconds and 16 seconds. In both cases use a breaking wave height of 1.5 metres. Make appropriate assumptions for values of other parameters in Queens formula and justify them.
4)Durability and lifecycle (5%)
Discuss the stages/process of deterioration for concrete structures exposed to a marine environment and provide a considered argument as to what stage of deterioration should the end service life of a structure be declared.

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