Abstract
This study was carried out to provide the basis for establishing a rational design method where requirements of both safety and economy in tunnel construction for the low strength deep ground are compatible. For the economic consideration of the tunnel construction, excavation works should be taken account as well as the support. Based on ground characteristic curves describing the relation between support pressure and ground displacement, following two curves had been developed for the checking of the design. One describes the relation between ground displacement and excavation limit which had been obtained by the sum of designed inner section, linning thickness and ground displacement. Another describes the relation between construction cost and ground displacement. The result of the study shows a better design indication for minimum excavation limit rather than minimum support pressure.
