Underground tunnel construction for environmental protection and resident consideration

A 1800 m long tunnel is planned in Tokyo, with a section width of 10 m and an excavated cross-section of 70 m² for each of the two tunnels. The ground consists of unconsolidated sand, and the conventional tunneling method will be used. Two main challenges need to be addressed: (1) The tunnel passes near wetlands inhabited by sensitive species and invaluable ecosystems, necessitating hydraulic and perimeter surveys to assess the potential impact of excavation on the environment. To mitigate these effects, the tunnel alignment was planned to avoid sensitive wetland areas. A waterproof structure was also designed, incorporating a 3D shell-spring analysis and reinforced bar placement at critical crossings. A Building/Construction Information Modeling, Management model was also developed for precise planning. (2) The tunnel portal is located near residential areas, requiring careful consideration of the surrounding environment. 3D simulations were conducted to evaluate noise levels in the temporary yard to manage noise pollution, and soundproofing measures were implemented. A 3D noise map was also created to facilitate clear communication with residents during explanatory meetings, ensuring transparency and minimizing disturbance. These solutions ensure the project progresses with minimal environmental and residential impact.