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On the Construction

1. Construction procedure

As for the construction procedure, several modular units are to be constructed at several factories. These are towed to the location site (See Fig.1). To reduce the construction period and to maintain structural quality, several modular units are constructed at multiple shipyards. Since a floating modular unit floats by itself, it can be easily moved freely in the horizontal direction in the man-made reservoir and, when connecting the floating modular units by welding and their supporting piles, vertical adjustment can be precisely controlled by changing the weight of the ballast water inside the floating modular units. This modular unit system makes it a very simple matter to change the whole size of a floating foundation at any time by adding or removing module units which had been tested successfully at open sea in the Mega-float Project in Japan during 1995-2000. Fig. 2 shows sectional elevation views of two different conditions of the floating modular unit. In this figure, (A) indicates the towing condition of the floating modular unit. This is the lightest condition of the 0.8 m draft since there is no ballast water inside of floating modular unit. Fig. 2 (B) shows the floating modular unit with ballast water at the planned site after the completion of construction of all buildings. The draft of floating modular unit is 3 m in this figure and the piles support the floating foundation with a rubber fender located on the piles. The total weight of the floating structure is both supported by buoyancy force and several supporting piles underneath of the floating structure.

Towing of modular unit by boats & Construction process of floating foundation

Floating foundations in reservoir

2. Enhancement scheme

The relocation of the existing floating foundations could be necessary as the new stage of the water city in future. In this situation, the existing floating foundations should not be taken off and can be reused again. So the floating foundations are to be reused several times on the condition that a water city is sustainable. Then the water city can easily be restructured to meet changing needs due to the movable nature of the floating structures. As for example of reconstruction procedure, the additional land area next to the first stage which is shown in Fig.3 would be excavated and filled with water when the additional construction of water city is required for the enlargement of water city. Fig.4 shows the scheme as to step-by-step procedure for enlargement of man-made reservoir. Here the additional floating foundations would be constructed at the shipyards and towed to their sites.

Enlargement of the water city with reservoir

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