部分飽和砂岩滑動與破壞之波動特性

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题名:	部分飽和砂岩滑動與破壞之波動特性
作者:	胡天騏;Hu,Tian-Chi
贡献者:	土木工程學系
关键词:	木山層砂岩;直剪試驗;加速度;音波;顯著頻率;Mushan sandstone;direct shear test;acceleration;sound wave;apparent frequency
日期:	2014-07-28
上传时间:	2014-10-15 14:27:37 (UTC+8)
出版者:	國立中央大學
摘要:	本研究採用改良式直接剪力試驗儀，進行砂岩試體之摩擦試驗及剪力強度試驗，在不同試驗條件下，配合不同之正向應力進行剪動，並利用加速度計及微音器量測砂岩在試驗中所產生之振波與音波訊號。將試驗結果利用頻譜比對法分析，可得本試驗所用岩石試體之加速度顯著頻率為1~16Hz，而音波之顯著頻率為10~15Hz，兩者皆屬低頻範圍而有密切之關係，且皆不受粗糙條件、正向應力及岩層間之裂縫是否有水而有所影響。根據不同粗糙條件下岩石摩擦試驗之破壞包絡線與降伏線，可得知在乾燥情況下降伏狀態與破壞狀態之摩擦比的範圍介於0.75~0.82；在濕潤情況下降伏狀態與破壞狀態之摩擦比的範圍介於0.79~0.83，此結果說明了濕潤情況下岩層達到降伏狀態的時間較晚，且達到降伏狀態後岩層抵抗滑動破壞的能力也較差。另外，根據岩石摩擦試驗之音壓、加速度、剪動位移及摩擦應力歷時圖可發現，當摩擦應力接近降伏摩擦應力時，所產生之位移雖較不明顯，但此刻之加速度與音壓卻有小幅驟升之趨勢，測得此訊號代表岩層已達降伏狀態，至於剪力強度則只能測得破壞時之訊號而無降伏狀態之訊號。一般而言，岩層滑動破壞通常包含局部之岩塊剪動與整個弱面的滑動，善加利用二者所發出之訊號，應可做好岩石邊坡滑動之預警工作。;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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