抄録
Special attention has been recently attracted to large-scale underground excavation for the purpose of utilization of underground space in the metropolis or some storages. This excavation brings about many problems concerned with ground environments such as surface subsidences, cave-ins, ground water movements and soon. The present paper, first, describes the feature of the cave-ins which the authors have experienced in the field of coal mining for a long period. Unlike the surface subsidences, the cave-ins of cavities remaining at shallow depths (within 20 meters approximately below the surface) suddenly occur several decades after mining, and may cause unpredictable damage to habitants or surface structures. Next, considering that underground structures are markedly irreversible (unreprodusible) ones compared with surface structures, the subjects which should be studied in underground development are proposed here; suitable arrangement of underground openings; planning of underground structures from a long-term viewpoint; and prediction of the ground movement and the flow mechanism of ground water and preventive measures against them.
