头汴坑溪一江桥上游河道震后之复建

Reconstruction of Tou Pien Keng Stream Upstream of Yi Chiang Bridge after Chi Chi Earthquake

台湾主要河川大都发源于中央山脉 ,上游坡降陡峻水流湍急 ,至中下流入平地后地势转缓 ,流速始渐滞缓。头汴坑溪一江桥位属头汴坑溪上游段 ,上游约 5 0 0 m处受到 1999年 9月 2 1日集集大地震断层错动影响 ,该河段右岸瞬间发生大规模山崩 ,致大量土石滑落将原有河道全部掩盖 ,水流无法向下游倾泄 ,随着地震后时间逐渐拉长 ,上游水位亦逐渐抬升 ,随时可能泛滥成灾而危及上下游居民生命财产安全。本研究收集该地区水文地文、地震后抢修抢险及复建工程设计施工相关资料 ,配合水理分析 ,提出妥善处理计划 。

Most of rivers rise from the Central Mountain in Taiwan. These rivers have torrential flow with steep longitudinal slope upstream, and moderate flow with mild slope downstream. Yi Chiang Bridge located at the upstream of Tou Pien Keng stream. Owing to“9·21” Chi Chi Earthquake, a landslide happened in the right riverbank about 50 meters above from Yi Chiang Bridge. It covered the channel, stopped the stream and increased the water stage by the time. It is necessary to canal the flood for the lives insurance. The dates of hydrology, the instant reconstruction, and the design and construction were collected in this study. They were used to do the hydraulic analysis and establish a proper flood control plan for the reference design.