Shigen-to-sozai, Vol.116, No.1, pp.7-12.
The Processes of Crack Development in Saturated Welded Tuff Specimen by Freezing and Thawing Cycles
Tiancheng CHEN1, Noriyasu MORI2, Takashi GOTO2
Teruyuki SUZUKI2 and Masahiro HIRAMATSU2
| I. Graduate School of Engineering, Kitami
Institute of Technology, Kitami-shi, Hokkaido
090-0017 2. Department of Civil Engineering, Kitami Institute of Technology |
| Freezing and thawing action as one of the
important external factors of rock slope
failures is emphasized incold regions. Investigations
were made on the crack development in saturated
welded tuff specimen by freezing and thawing
action in this study. The freezing test was
conducted in a temperature-controlled chamber
in the laboratorywhere temperature varied
from + 5 'C to -18 'C. The freezed rock specimens
were thawed in distilled water. The test
lasted 3.5 hours for each freezing and thawing
cycle including 2hr for freezing and l.5hr
for thawing. P-wave velocity and acoustic
emission of specimens were measured during
freezing. The investigation on change of
appearance on outer surface and section of
the specimen as well as pore water migration
and crack development were done. The initial cracks in rock specimen by freezing-thawing action started from the weak of surface layer such as pumice, mudstone and the interface of gravel and volcanic glass, then propagated to inside of the specimen. The cause is that the degree of saturation in surface layer is higher than that of inside due to pore water migration during freezing. The patterns of cracks by freezing and thawing is affected by the rock structure and pore water migration. |
| KEY WORDS: Freezing and Thawing, Saturated Welded Tuff, Crack Development, Pore Water Migration |