Casestudie naar caisson golfbreker voor LNG terminal in Hazira, India

Casestudie naar caisson golfbreker voor LNG terminal in Hazira, India

Carstens, P.F.

Vrijling, J.K. (mentor)
Noppen, H.P. (mentor)
Tutuarima, W.H. (mentor)
Reedijk, J.S. (mentor)

Civil Engineering and Geosciences

2001-09-01

Delta Marine Consultants BV are carrying out the design of a port and Liquified Natural Gas (LNG) receiving terminal at Hazira, Gujarat, North-west India. An essential element of the port is a breakwater, to provide shelter against the waves, currents and sediment transport in the port. The abundance of knowledge and experience in the design of rubble mound breakwaters, in combination with the simplicity of technology, resulted in DMC adopting a rubble mound breakwater for the LNG terminal. The question is whether constructing this type of breakwater, in natural stone, is the best solution for Hazira. It is possible that a caisson breakwater may prove a more satisfactory alternative in this case. This study attempts to answer to this question. The planning, costs, risks and the execution are examined. Based on this specific case, the choice between the two types of breakwaters will be explained. This exercise is intended to make this selection simpler for future breakwater projects. Consideration of the aspects that influence the design of the breakwater indicated that the presence and accessibility of suitable quarries to be as important as the hydraulic conditions at the site determining the economics of the breakwater. Research into the construction methods of the caissons, the execution, the costs and the possible risks, are also of great importance. These aspects are analysed in this study in order to make a selection between the rubble mound breakwater and the caisson breakwater. To obtain information regarding the influence of certain factors on the economic choice between the types of breakwaters, a sensitivity analysis has been carried out. By altering the unit price of the concrete, the quarried rock and the reinforcement steel, the 'break-even point' has been determined. At this point there is no difference between the costs of both types of breakwaters. To make the correct choice for future breakwater projects, two variables are very important: the length of the breakwater and the water depth at the location. It appears that these two factors are crucial for the design. The results of the sensitivity analysis for the length of the breakwater indicate that beyond a length of 1525 meter the caisson breakwater is economically the most attractive choice. The constant costs will be divided up not enough meters of breakwater, resulting in a rubble mound breakwater choice. The corresponding break-even point for the depth is approximately 18 meters. Based on the results of the risk analysis it can be concluded that the benefits of the caisson breakwater are that the caissons can be prefabricated off-site, transported to site off-shore and then sunk into position off-shore as well. Minimal disturbance to the local environment will be the result. In contrast to the 500 trucks that will drive through overpopulated areas when the breakwater will consists of rock. Detailed research has to be carried out to confirm this assumption. This study concludes that in the case of long breakwaters (>2100 m) in large water depth, the caisson breakwater will be an economic alternative to a rubble mound breakwater. The apparent conclusion favouring a caisson breakwater is a generalisation. The true situation relating to project economics is far more complex. The presence of cheap labour, local construction expertise, the availability and cost of transporting natural material will have a significant influence on the conclusions. In the completion of a mayor project such as this proposed port, consideration of the potential variables and their influence are principal concerns for the client and the designer. At the present time it may be concluded, from the results of this study, that in case of Hazira the caisson breakwater is the most attractive type of construction. Most attractive corresponding the price, the value and the risks.

breakwater design
caissons
rubble mound breakwater

http://resolver.tudelft.nl/uuid:a1e66474-9163-4f7d-b419-adb37f59f7b9

TU Delft, Civil Engineering and Geosciences, Hydraulic Engineering

Student theses

master thesis

(c) 2001 Carstens, P.F.