It'll be made from concrete caissons filled  with sand.

它将由充满沙子的混凝土沉箱制成。

OCEANIX, which is constructing an  entire floating city in South Korea, is placing everything on platforms  made from concrete caissons.

OCEANIX 正在韩国建造一座完整的漂浮城市，它把所有东西都放在由混凝土沉箱制成的平台上。