PROBLEM TO BE SOLVED: To provide an underground base structure permitting growth of planted trees and storage of a relatively large amount of rainwater at the same time.SOLUTION: The underground base structure includes a tree growing base region which has a number of coarse-grained materials and in which a frame is formed by crossing the coarse-grained materials to form a first space for the roots of the trees to enter and a rainwater storing base region in which more rainwater per unit volume can be stored than in the tree growing base region. A growth assistant material whose particle size is smaller than that of the coarse-grained material is attached to the coarse-grained material for assisting the growth of roots of the trees. In the underground base structure, the tree growing base region is disposed adjacent to the rainwater storing base region.COPYRIGHT: (C)2012,JPO&INPIT【課題】 植設された樹木の生育を可能としつつ、比較的多くの雨水の貯留を可能とする地下地盤構造を提供する。【解決手段】 多数の粗粒材を有し、該粗粒材がかみ合わされて樹木の根が進入可能な第1の空隙部を形成するように骨格が形成され、前記粗粒材に、該粗粒材よりも粒径が小さく樹木の根の成長を補助する生育助材が付着されてなる樹木生育用基盤領域と、単位体積当たりにおいて前記樹木生育用基盤領域よりも雨水を多く貯留可能な雨水貯留用基盤領域と、を備え、前記樹木生育用基盤領域と前記雨水貯留用基盤領域とが隣接するように配置されて構成されたことを特徴とする。【選択図】 図1
