圖書典藏及影音數位平台

秀姑巒溪流域位於台灣東部，地跨花蓮、台東兩縣。其北接花蓮溪流域，南與卑南溪流域相鄰，主流秀姑巒溪發源於中央山脈崙天山南麓，東流入台東縱谷後，受海岸山脈阻擋，乃沿縱谷平原向北流，在匯納兩岸諸水後，於瑞穗鄉舞鶴山前再折轉向東流，並以其巨大侵蝕力橫切海岸山脈，而在豐濱鄉大港口附近流入太平洋。流域行政區域包括台東縣之海端、池上與花蓮縣之富里、卓溪、玉里、瑞穗、萬榮及豐濱等八鄉鎮。本溪流域為台東縱谷平原三大水系之一，流域面積1,790.46平方公里，其在花蓮縣部份，占全縣面積三分之一強，居住人口約十萬人，占縣人口三分之一弱，主流全長81.15公里，為全台21條中央管河川之一。主要支流有五條由南至北依序為：樂樂溪、卓溪、豐坪溪、紅葉溪及富源溪。 秀姑巒溪現況防洪構造物多屬老舊堤防，為能尋求有效維修與補強方案，擬藉由安全性評估計畫來全面檢視秀姑巒溪堤防之安全，以利後續維護管理。 本計畫主要目的為暸解秀姑巒溪堤防結構現況，先以人員目視進行檢查並提出期初報告，後續採用非破壞檢測方式如透地雷達探測、震波測勘等，檢查堤防構造物之使用狀況與內部損壞狀態，包含結構體內部裂縫及淘空狀況等情形，以便未來做為堤防管理、維護之參考依據，以及尋求有效維修與補強方案，擬委外辦理安全性評估分析及研擬改善方案。

The current flood proof structure of Xiuguluan River is old levee. The potential risk caused by the climate change, extreme rainfall incident and flow route changes in recent years is considered. In order to understand the current structure situation of Xiuguluan River, the visual inspection of levee surface is carried on by personnel first. Then, the non-destructive ways, such as ground penetrating radar, seismic way, are adopted to inspect the use condition and internal damage status of levee structure, so that the results can be used as the reference basis for future levee management and maintenance. The safety assessment and analysis as well as the improvement measures will be handled to seek for effective maintenance and reinforcement alternatives. In this project, three times of visual inspection were conducted for 26 levees in 39,825m total: As for the non-destructive inspection, 32,400m was inspected by the ground penetrating radar, and 500m was inspected by the seismic wave; 18 places of river levee were investigated for structural strength, the drilling core test was used mainly, and the cross inspection results of resilient hammer test and impact echo method were used for verification. The safety assessment for current situation of levee was conducted by integrating various inspection outcomes, and the improvement countermeasures were drafted in accordance with the assessment result. There were 17 damaged places from visual inspection, including 9 places at Xiuguluan River, 4 places at Zhuo River, and 4 places at Fengping River, and the damage level was the planned improvement. The ground penetrating radar was adopted to detect the clean-out of levee in 34,927.5m of longitudinal length. It was found that there are 1,995.5m of light levee undermining and 31.0m of medium levee undermining, which accounted for 6.06% and 0.09% of total longitudinal length. Take a broad view of the detection results, most of damage was near around the crevices in front of the levee. The results of Impact-Echo Method show that there is no obvious diffraction wave signal, so estimate that there are weak surface at levee structure because of penetrating crevices. It will easily allow water to infiltrate into the levee to gradually take away some soil at the bottom. Finally, the soil subsidence within the levee and levee undermining will be caused. Some of the undermining area is also located near the construction joint, and its mechanism of action is the same. 350m long was detected by the seismic wave. It was shown that the speed of wave could be used to represent the dense or loose state of same material. The result of drilling core test was between 150 kgf /cm2 ~ 458 kgf /cm2, wherein the concrete strength of Xinzhuang Levee was slightly low, and there was above 150 kgf/cm2 for other levees. According to the above inspection results and with reference to “Technical Guidelines for Hydraulic structures Inspection and Safety Evaluation”,” Technical Methods for Hydraulic structures Inspection and Safety Evaluation”, Water resources agency, and “Management Guidelines of Security Facilities for River banks and coasts”, Japan Harbor Institute of technology and so on. There are total 135 assessment sections, of which 36 sections are planned improvement sections and 99 sections are normal sections. Most of the damage points in scope of project are crevices. In part of damage points were detected which are medium levee undermining. Those damage points will be repaired by large cave repair method. The other damage points in the scope of project will be repaired by the surface closed method and local patching method mainly, in order to prevent the exterior water from invading the levee body continuously. It is estimated that the maintenance and repair fee is about NT$ 501,000.