ABSTRACT
The idea of underground space utilization is to relocate many surface functions underground, thereby increasing the serviceability, amenity, and safety of the city. The primary aim of underground space utilization is to counteract urban congestion problems, such as traffic jams and crowded lifelines, and environmental deterioration. The focus of using underground space is placed on “the regeneration of a city” where underground space has become the key element to attaining a high quality of life in the city. There are two major technical features of tunneling technology. One is the need to use deeper underground space and the second is the need to create large-diameter caverns and tunnels. Technology of the deep underground, up to 100 m below the surface, is becoming important for soil and soft rock grounds, especially in Japan. The need for large-diameter tunnels and large-sized caverns, for road traffic and other purposes, will continue to increase.
