| 摘要 |
PURPOSE: The structure of an underground tank is provided to avoid dense arrangement of reinforcements even when a side wall and a bottom plate are rigidly connected by forming the polyhedral underground tank of which the under face of the bottom slab projects downward. CONSTITUTION: An underground tank is a hydraulic pressure-resistant slab type reinforced concrete tank provided with a bottom slab(1) which can withstand and underground water pressure. When constructing it, a continuous underground wall(2) is constructed first in the periphery of the construction site to cut off water. Then, the site surrounded by the continuous underground wall(2) is excavated down to the under face of the bottom slab(1). Then, concrete is placed for the bottom slab(1) and the side wall(3). The side wall(3) and the bottom slab(1) are rigidly connected to each other without joints between them. The bottom slab(1) is so shaped that the under face(7) projects down. That is, the central part is projected down most to form many slope faces at the periphery. Accordingly, the under face(7) has such a shape that the spherical surface is combinedly constituted of many planes. In this way, the flow of stresses in the fitting part of the side wall(3) and the bottom slab(1) is made smooth and hence, excessive bending moment generating in the structure is moderated.
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