抄録
This paper examines the fundamentals of underground development and its utilization, including the maintenance and management before, during, and after the planning and construction. It is expected that underground spaces will be densely concentrated within a given region. New problems will arise as follows: the suitable arrangement of underground openings, subsidence and instability due to weathering of the ground around the openings, changes in ground water flow, and so on. Once the underground space has been constructed, it is impossible to return the environment to its initial conditions. In addition repair and reconstruction due to damage are nearly impossible. Therefore, this paper discusses the durability (i.e. durable life) of underground structures from economical, functional, and physical points of view. Especially, the long term stability of underground openings is investigated in detail in connection with several previous accidents. In the future, it is necessary to recognize that “underground developments must be dealt with different from surface ones”. Success of projects depends on planning and maintenance done from a long-term viewpoint, including careful study concerning the affects such systems will have on society.
