地盤陥没災害と地下空洞調査について

抄録

There are many abandoned coal and lignite mines, underground shelters excavated during the Second World War, hastily filled underground rooms and pipes during the re-construction following the Second World War all over Japan. Due to degradation of these cavities, sinkholes or ground subsidence resulting in casualties and damages to residential areas properties have been increasing in recent years. In addition, torrential rains and/or earthquakes make necessary to investigate the instability of such abandoned underground cavities.
The behavior of rock mass between the ground surface and shallow underground openings is very complex and it is affected by the mechanical behavior (deformation, local failures, loosening), weathering, and deterioration, following the excavation, underground water seepage. In this article, the author describes damages caused by ground subsidence, sinkholes and their mechanism associated with environmental factors, the collapse risk of abandoned mines. Furthermore, the importance of the development of exploration and surveying techniques to detect the location and geometry of abandoned underground cavities is disccused.