| 摘要: | 本研究主要為蒐集莫拉克颱風侵臺期間，各受損橋梁之現地資料與結構資料，經由地理資訊系統整合後進行案例分析，並藉由專家訪談驗證，以探求橋梁致災之主要因素。本研究將此次莫拉克風災毀損橋梁之致災類型歸納為五類，分別為(1) Type I土石流撞擊，(2) Type II過大洪峰流量，(3) Type III橋址位於水路攻擊處，(4) Type IV邊坡崩塌，以及(5) Type V基礎淘刷。其中，又以Type I及Type II類型毀損橋梁數量為最多，故本研究以此兩類之毀損橋梁為研究對象進行致災數據分析，並藉由歷史颱風之雨量進行驗證，以求其破壞臨界線。 此外，本研究並進而探討橋梁災前、災中、及災後之維護管理機制。其中，災前首重工作為汛期前針對可能致災類型之備災與補強；災中則為橋梁本身結構與環境資訊之監測，封橋預警機制方面可利用本研究之破壞壞臨界線加以輔助；災後重點為復建工程進行前之緊急應變機制，結構嚴重受損之橋梁，以規劃替代路線或採適用之便道、便橋搶通為主。 本研究主要之成果包含(1)毀損橋梁之資料蒐集，(2)致災因素分析，(3)分析橋梁結構資料與環境資料之破壞臨界線，以及(4)探討現有橋梁面臨風災之維護管理機制，希能對受災橋梁之復建工程與橋梁維護管理層面有所助益。 This research aims at collecting relevant data for the bridges which were damaged by typhoon Morakot that hit Taiwan in August, 2009, such as satellite photos, geographical pictures and maps, including rivers and land-sliding areas near by the damaged bridges. All the above data, along with basic bridge structural data, levels and volumes of water current, and data of rainfalls, were integrated by a geographical information system to investigate the vulnerability factors for the damaged bridges. Five vulnerability factors were concluded: (1) Type I: Impacts of debris flows, (2) Type II: Massive currents and floods, (3) Type III: Bridge located at the waterway front, (4) Type IV: Land slides near bridges, and (5) Type V: Scouring of pier foundations. Among these factors, Type I and II were the most common factors for which bridges were damages. Thus, critical boundary lines of rainfalls were drawn for future reference based on the rainfalls due to typhoon Morakot and other historical typhoons. This research also investigates proper bridge management and maintenance mechanisms for various phases when disasters occur. Before a disaster occurs, the most important tasks are preparation and reinforcement of vulnerable bridges; when the disaster occurring, monitoring of structural components and nearby environments become critical; and after the disaster occurs, construction of temporary bridges and planning of alternative routes are crucial. Results of this research can be concluded as (1) collecting of relevant data for damaged bridges, (2) analyzing vulnerability factors, (3) analyzing critical boundary lines of rainfalls, and (4) proposing proper mechanisms. Findings of this research should be helpful to the reconstruction of damaged bridges and to future disaster prevention efforts. |
