| Summary: | 碩士 === 國立交通大學 === 土木工程學系 === 84 === The research is aimed to investigate the effect of undrained
dynamic cyclic loading and degree of saturation on the
mechanical behavior of colluvial deposit, such as Hu-Ko and
Chin-Qua-Shih soil, by conducting experiments of UU triaxial
tests and isotropic triaxial consolidation tests. The mode of
theundrained cyclic loading is regular sine wave with the
frequency of 1 Hz, and the peak amplitude of the wave is 1/6 the
peak strength of static undrained triaxial test under the same
condition. After being carried out the undrained cyclic
loading, the static undrained triaxial test will be applied to
the specimen for comparison to the strength of originally static
undrained test. The results show that: (1)The undrained
triaxial shear strength decreases with increasing degree of
saturation. Above 80% degree of saturation, the strength
reduction trend becomes gentle. (2)The degree of saturation
influences the friction angle of UU condition. When the soil
reaches 100% saturation, the friction angle will be close to
zero. (3)Dynamic cyclic loading decreases the peak shear
strength, friction angle and cohesion of the soil. (4)The shear
strength reduction after dynamic cyclic loading (Fred) bear a
log-log relationship with the normalized excess pore water
prassure excited by dynamic cyclic loading shown as follows： .
The relation can be used as a prediction model of in-situ soil
strength after earthquake. (5)Degree of saturation influences
the soil compression index enormously beyond the extend of
double.
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