地表振動之偵測技術應用於大型山崩之研究

2009年莫拉克颱風在台灣南部山區出現超過2,000mm的降雨量，導致許多集水區發生大量的山崩、土石流事件。其中，有12個面積大於0.3 km^2的大型山崩事件，可以由鄰近地震站的地表振動記錄中判讀出來。從分析結果發現，當崩塌塊體的運動時間(Δt)超過60秒時，崩塌面積(A)的大小，是與塊體運動時間的長短呈正相關。反之，崩塌面積則會受到崩塌地的幾何形狀所控制，而且崩塌塊體的運動距離(D_(runout_)，與運動時間的平方成正相關，此現象也符合了塊體運動的能量守恆。從地震站記錄之崩塌的運動時間，可以利用Δt-D_(runout)之關係式D_(runout)=0.198•Δt^2+1296，來對塊體的運動距離，邊坡材料的摩擦係數，以及崩塌發生時的降雨條件進行更進一步的評估。

關鍵字

大型山崩；地表振動；塊體運動距離；降雨門檻

並列摘要

After 2009 typhoon Morakot, twelve large-scaled landslides with disturbed area ＞0.3 km^2 were located seismically by detecting ground-motion waves collected by broadband seismic monitoring. Through combined with geometric characteristics from high-resolution remote sensing images, the behaviors of sliding mass movement and geomorphic change on landslide-hill can be characterized. The results show that landslide-disturbed area is dominated by landslide duration (Δt) when Δt is longer than 60 seconds, whereas it is dominated by geometric shape of landslide source when Δt is shorter than 40 seconds. The run-out distance of sliding mass (D_(runout)) is also demonstrated to have a positive relation with Δt^2 (D_(runout)=0.198•Δt^2 + 1296), which is consistent with energy conservation during mass movement. Therefore, this Δt-D_(runout) relation would be useful for estimating D_(runout) and the friction coefficient of failure material. Besides, the accurate time of landslide initiation is extracted from ground-motion waveforms to build the climatic condition for large-scaled landslides. That is I=60.D^(-0.31) (I is rainfall intensity in mm per hour and D is rainfall duration in hours).

並列關鍵字

Large-Scaled Landslide ； Ground-Motion ； Runout Distance ； Rainfall Threshold

國際替代計量

地表振動之偵測技術應用於大型山崩之研究

全文下載

主題瀏覽