Abstract
Underground electric power and heat supply pipelines have been constructed in the central urban area of Utsunomiya in connection with the project of a new substation and local heat supply service by Tokyo Electric Power Company. NATM was partially adopted for the excavation method accounting for the influence on environments and economical factors.
The length of 91.19m was excavated through the soft rock by a partial face machine. The cavern could be completed including the section with the small curvature and various cross sectional shapes. The open shafts excavated for the vertical manholes were jointed with the tunnnel previously excavated.
Additional monitoring was carried out grasping the influence on the surrounding ground and observing the tunnel behavior.
