Strain measurement of NRLM tunnel using a laser extensometer

摘要

Twelve years observation of strain changes of a concrete tunnel in the soil was carried out using a laser extensometer at Tsukuba, in the eastern part of Japan. The term is from 1980 to 1992. A dominant component of the strain changes is an annual change and its amplitude reaches to 8 x 10~-6. Linear trends were also observed. Irreg- ular and rapid changes were observed. A model of strain change for the effect of out- door temperature was constructed empirically using observed strains, out door tempera- ture and temperature on the floor of the tunnel during 1986-1992.