| Summary: | 碩士 === 國立中央大學 === 土木工程學系 === 102 === This research used sandstone specimens to perform a series of friction tests and shear tests under various experimental conditions by modified direct shear apparatus. In the tests, the data of vibration waves and sound waves was measured by accelerometer and microphone. According to the results of experiments, the apparent frequency of acceleration of the rock specimens used in this research is 1-16 Hz and the apparent frequency of sound waves is 10-15 Hz. Both of these apparent frequencies were found in the low area of frequency. Moreover, conditions of roughness, normal stress and the amount of water filled in the cracks of rock would not affect the apparent frequency. According to the failure envelope and yielding line of friction tests, it is recognized that the range of friction ratio between yield and failure under dry condition is 0.75-0.82. However, its range for the wet condition is 0.79-0.83. This showed that the wet rock will reach the yielding state later than dry rock and the sliding resist is weak also. Besides, according to the figures of sound pressure, acceleration, shearing displacement and frictional stress with the elapsed time obtained from the friction tests of rock, it is recognized that although the slide displacement occurred in the experiments is not apparent, the acceleration and the sound pressure increased slightly at the beginning of yielding. These signals show that the rock has reached yielding state. However, for the shear of rock, it has no apparent signals for yielding, and only offers some significant signals at failure. The combination of these information measured from rock slope may be used as an early warning.
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