愛玉子溪土石流之地動訊號特性與警戒方法之探討

Characteristics and Warning Methods of Ground Vibrations Generated by Debris Flows at Ai-Yu-Zi Creek

魏士超(Shih-Chao Wei) ； 劉格非(Ko-Fei Liu) ； 黃亦敏(Yi-Min Huang) ； 方耀民(Yao-Min Fang) ； 尹孝元(Hsiao-Yuan Yin) ； 黃效禹(Hsiao-Yu Huang) ； 林建良(Chien-Liang Lin)

《中華水土保持學報》 49卷2期 (2018/06) Pp. 77-88

https://doi.org/10.29417/JCSWC.201806_49(2).0002

摘要

由地聲去監測土石流，除了可反應流況的特性也可用於事件的判釋。為了透過地聲訊號建立土石流的判釋或警戒方式，本文以四場愛玉子溪的土石流為例，探討土石流事件的訊號特性，並依此有系統的建立判釋指標與警戒門檻值。透過比較能量的平均延時及特徵頻率，本研究萃取出適用於判釋土石流的累積能量與累積能量斜率指標，並由事件前的環境雜訊去建立該指標的警戒門檻值。透過浮動式門檻值計算的警戒時間中，本文成功的透過兩場事件驗證土石流的到時，其最大誤差僅4.2秒。

關鍵字

土石流 ； 地聲 ； 警戒門檻值

並列摘要

Ground vibrations provide relevant flow conditions and may be used to warn of potential debris flow. To construct warning methods for debris flow, geophone ground vibration recordings from four debris flows at Ai-Yu- Zi creek were analyzed. Based on time-frequency analysis, the effect of time span and frequency band were examined, and the representative indexes of accumulated power and accumulated power slope were extracted. With extracted indexes, we used ambient noise and scale factors to define warning thresholds. The warning times for debris flows were calculated with floating warning thresholds and then successfully validated by two events with a maximum error of 4.2 s.

並列關鍵字

Debris flows ； geophone ； warning threshold