英文篇名
Study on the Soil Liquefaction Damage of the 2018/02/06 Hualien Earthquake
作者
黃富國、王淑娟、費立沅、邱禎龍、蘇品如、蘇泰維
關鍵字
花蓮地震、米崙斷層、土壤液化
摘要
發生於2018年2月6日之花蓮地震,芮氏地震規模6.26,震源深度6.31公里,屬淺源地震;位於花蓮縣立霧溪沖積扇近海的震源,觸動了米崙斷層及嶺頂斷層錯動,在花蓮市之震度高達7級,斷層二側附近地震紀錄呈現明顯之近斷層速度脈衝現象,垂直最大地表加速度與水平最大地表加速度數值相當,甚或較大;此次地震前震及餘震不斷,主震時雖然強震延時僅10秒左右,但從米崙斷層帶上之華西路至嶺頂斷層帶上之崩坎,離震央30公里的範圍內,多處發生了土壤液化現象,尤其在花蓮火車站前站西起國聯五路,東至國盛七街美崙溪畔,南起商校街,北至國盛八街的0.2平方公里範圍,有較明顯之地盤下陷,及建物震損的情況。液化損害之類別包括:建築結構及港灣設施地基震害、維生管線震害、土工結構及橋梁樁基震害、地盤側向擴展及流動破壞等。本文根據此次土壤液化震害之調查結果,進行初步探討,顯示前期振動對液化的影響,及「液化加震」對建築物的效應,希望成果可以提供本土化液化評估,及擬定液化防治對策的參考,以避免或降低液化震害對生命財產及工程設施可能產生之影響。
英文摘要
The 0206 Hualien earthquake occurred in northeastern Taiwan at 23:50 on 6 February 2018. The epicenter of the earthquake was at 24.1°N and 121.73°E with a focal depth of 6.31 km and a magnitude 6.26 (ML). The seismic intensity was up to Level 7 in the seismological station of Hualien City. It caused building collapses and 17 fatalities in Hualien. There were many foreshocks and aftershocks in this event. Although the strong motion duration is only about 10 sec, many areas, from the Huaxi road located at the Milun Fault zone to Bengkan along the Lingding Fault at a farthermost distance around 30 km from the epicenter of the earthquake, were subjected to soil liquefaction.
According to the reconnaissance survey, the main area suffered from the soil liquefaction damage was about 0.2 km2 and was in the range near the front exit of the Hualien Train Station. The sites with obvious liquefaction evidences, including the ground settlements and tilting of buildings, were located from Guolien 5th Rd. to Guosheng 7th St. in the west-to-east direction, and Shangxiao St. to Guosheng 8th St. in the south-to-north direction. Four types of failure modes were identified, they include: foundation failures of building and harbor facilities, lifeline damages, damages of earthworks and pile foundation of the bridge, and lateral spreading and flow failure. The survey indicated that the effect of pre-shaking on the triggering of liquefaction is very important. Moreover, the probable effect of seismic amplification on structural safety at liquefied sites is observed. Therefore, more efforts should be required to strengthen the related researches, such as liquefaction mechanism, hazard analysis, retrofit and countermeasures for disaster reductions, to prevent or mitigate the possible damages induced by soil liquefaction.