1996 Volume 42 Issue 3 Pages 155-166
Twelve years observation of strain changes of a concrete tunnel in the soil wascarried out using a laser extensometer at Tsukuba, in the eastern part of Japan. Theterm is from 1980 to 1992. A dominant component of the strain changes is an annualchange and its amplitude reaches to 8×10-6. Linear trends were also observed. Irregular and rapid changes were observed. A model of strain change for the effect of outdoortemperature was constructed empirically using observed strains, out door temperature and temperature on the floor of the tunnel during 1986-1992. By eliminating cornponents caused byoutdoor temperature change, it becomes more simple to recognizestrain changes of the tunnel. Linear trend of the tunnel strain looks like changedafter 1984. From 1988 to 1989 a big strain change reaching 8×10-6 was observed.
