ABSTRACT
A 1,800 m long tunnel is planned in Tokyo. The target ground is unconsolidated sand. The tunnel section width is 10 m, and two tunnels with an excavated cross-section of 70 m2 are planned. The tunnel excavation method was the conventional method.
The following two problems must be solved in this tunnel.
The tunnels are surrounded by wetlands inhabited by valuable species, and a hydrological survey and study are necessary to determine the impact of tunnel excavation.
Since there are houses and steel towers above the tunnel, the impact of ground subsidence due to tunnel excavation should be ascertained. Countermeasure works, and measurement plans should be developed in advance.
