A method for constructing a storage tank, comprising:
- laying a concrete bottom plate on a bottom part of a hole dug in the ground;
- constructing a storage assembly on the bottom plate and accommodating the storage assembly in the hole;
- constructing a side-wall formation member configured to form a concrete quadrangular tubular side wall surrounding the bottom assembly on the bottom plate;
- and forming the side wall by pouring fresh concrete into a space between inner molds and an outer mold of the side-wall formation member and hardening the fresh concrete,
- wherein a plurality of square tabular partition plates each of which has at least one cylindrical rib protruded on a lower surface thereof and at least one cylindrical rib protruded on an upper surface thereof and a plurality of tubular spacers each of which is connected to one or both of the lower surface and the upper surface of each partition plate while being fitted to the cylindrical ribs are prepared before constructing a storage assembly on the bottom plate and accommodating the storage assembly in the hole,
- constructing a storage assembly on the bottom plate and accommodating the storage assembly in the hole comprises providing an outermost layer part by alternately arranging the partition plates and the spacers in a vertical direction on the outermost side of the storage assembly,
- constructing a side-wall formation member configured to form a concrete quadrangular tubular side wall surrounding the bottom assembly on the bottom plate comprises:
- forming each of multi-step inner molds into a quadrangular tubular shape by arranging a plurality of first plate members in such a manner that the first plate members come into contact with portions, which form an outer surface of the outermost layer part, of the plurality of tubular spacers constituting the outermost layer part in accordance with each step between the multi-step square tabular partition plates which constitute the outermost layer part and are arranged at intervals in the vertical direction;
- inserting a plurality of vertical reinforcing bars into the multi-step square tabular partition plates which constitute the outermost layer part and are arranged at intervals in the vertical direction in such a manner that the vertical reinforcing bars are placed on the outer side of the plurality of first plate members;
- and forming a single-step outer mold into a quadrangular tubular shape by holding a plurality of second plate members, which are arranged on the outer side of the multi-step square tabular partition plates which constitute the outermost layer part and are arranged at intervals in the vertical direction, by a plurality of separators to form a predetermined gap between the second plate members and the vertical reinforcing bars.