Masayuki Tsutsui

EXPLORATION AND SECONDARY LINING DESIGN FOR SWELLING GROUND

Secondary lining of tunnels is used to increase the safety factor of primary supports, and is not generally subjected to loading. However, it is regarded as supporting members in swelling ground, earth ground with an extremely low strength ratio. Nevertheless, it is difficult to estimate the loads that will act on secondary lining after it is put into use, and the design method for reinforcing secondary lining concrete is yet to be established, to ensure the long-term stability of tunnels. The authors had an opportunity to design the secondary concrete lining as supporting members in the serpentinite ground of the Dai-ni Imaizumi Tunnel along the Kyushu Shinkansen. In this paper, the procedure of exploring, measuring and design employed to solve such a problem is reported. They also discuss the generated stress of the secondary lining and the displacement behavior of surrounding ground on the basis of the measurement.