STRUCTURE OF UNDERGROUND DAM

PURPOSE:To reduce a site required for constructing a storing tank and to reduce the construction period and the construction cost by arranging a storing tank having water permeability and a storing tank having impermeability connected in a line using a water barrier wall as a boundary on the water barrier wall. CONSTITUTION:Water permeable filling material 5 such as ballast or the like is charged in the hemihedry where catchment holes 13 are bored between the machine peripheral surface of a caisson body 1 and a steel frame fitted to the caisson body 1, and impermeable filling material 6 is charged in the remaining hemihedry thereof. The caisson 1 is buried in such a manner that the other side of the catchment hole 13 side is opposite to a flow of underground water. After plural caisson bodies 1 are submerged at equal spaces, the steel frame is pulled out to construct storing tanks 14, water barrier walls 7 are constructed in such a manner as to connect between the storing tanks 14 or be connected to both ends of the storing tank 4 through a joining steel plate 8. Underground flowing water cut off by the water barrier wall 7 can be stored in the storing tank 14 through the water permeable filling material 5 and the catchment hole 13.