礫石受剪之音波與振波及其防災應用

Sound and Vibration Waves of Gravel Due to Shearing and the Application in Disaster Prevention

張惠文(Huei-Wen Chang) ； 陳柏翰(Po-Han Chen) ； 李嶸泰(Jung-Tai Lee) ； 胡天騏(Tien-Chi Hu)

《災害防救科技與管理學刊》 2卷2期 (2013/09) Pp. 55-77

https://doi.org/10.6149/JDM.2013.0202.04

摘要

本研究以直接剪力試驗儀進行礫石材料之剪動試驗，量測試驗時礫石所產生之音波與振波，探討其訊號之處理與判讀方式，藉以瞭解礫石受剪時，尤其是降伏後至破壞時之音波與振波特性。為找出礫石之音波與振波之顯著頻率分佈範圍，本研究確立了頻譜比對法，可用以判斷音波與振波之變化，訂定顯著頻率，並予以濾波。經比對後，發現在15 Hz範圍內礫石受剪所發出音波之數值明顯增高，可視為其顯著頻率。利用此法可方便且迅速地找出顯著頻率。另外亦發現此主要頻率不因含水量之多寡而有所變動。至於振波加速度頻譜圖亦有類似之性質，說明了振波加速度與音波間有密切之相關性，且相較於音波訊號，加速度訊號較不易衰減，可與音波訊號互相結合，輔助判斷，以為防災預警之用。

關鍵字

剪力試驗 ； 音波 ； 振波 ； 加速度 ； 顯著頻率

並列摘要

This research performed a series of direct shear tests of gravel material to study the properties of shear strength, sound waves and vibration waves. A spectrum comparison method of waves is proposed in this paper to distinguish and to filter the sound waves and vibration waves generated in the process of shearing. According to the results of experiments, it is found that within the area smaller than 15 Hz, the magnitude of sound waves increased apparently compared to that of background noise and this can be seen as the apparent frequency or main frequency of this gravel material. The magnitude within this frequency area varied slightly in spite of the variation of water content. There are similar properties between the spectrum of acceleration of vibration waves and the spectrum of sound waves. This shows that there exists a close relationship between sound waves and vibration waves. Conversely, the acceleration signal does not decrease apparently, so it can be combined with the sound signal to distinguish the yielding and failure of gravel material.

並列關鍵字

Shear test ； Sound wave ； Vibration ； Acceleration ； Apparent frequency

參考文獻

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