蘭陽溪堤防安全性評估分析研究計畫(1/2)成果報告書(附2光碟)

蘭陽溪水系為宜蘭縣境內最大河川，屬中央管河川；主要支流包括羅東溪及宜蘭河，本計畫範圍為主流左岸之壯圍、員山、再連、長嶺、崙埤及松羅堤防與右岸之牛鬥、東壘、碼崙二號、碼崙及碼崙一號堤防，兩岸合計約21,661公尺。因本溪水系現有防洪構造物歷經多年風吹日曬及颱風豪雨後，發現部份堤頂已有下陷、淘空滲砂與材料劣化等現象發生，並歷經民國101年蘇拉颱風等沖刷影響之後，造成局部堤防受損亟需評估其安全性，為能尋求有效維修與補強方案，故就本河川進行安全性評估分析及研擬改善方案，以提供未來做為管理、維護之參考依據，爰以辦理本計畫。
計畫內容主要為河堤檢測及資料蒐集分析建置兩部分，其中河堤檢測部份包括：河堤構造物現場勘查，其範圍為蘭陽溪兩岸，共完成3次現場勘查，計有50處損壞，經目視損壞分析評估，計畫改善有48處，注意改善有2處，破壞類型主要為裂縫損壞計34處、其次為坑洞損壞6處。另非破壞性檢測採透地雷達進行堤防淘空探測，完成測線長度35,937公尺，檢測成果堤防輕微淘空總長度136公尺，無中度淘空及無嚴重淘空訊號；此外透過透地雷達檢測、敲擊回音法檢測、反彈衝錘試驗及鑽心試驗交叉驗證，其驗證成果大多吻合，因此本計畫採用透地雷達進行河堤構造物檢測，其成果可充分掌握河堤構造物內部結構現況。
The Lanyang Creek System is the largest one inside Ilan County administered by the central government; its main tributaries include Luodong Creek and Ilan River. The scope of this project consists of dikes on the left bank of the main branches such as Zhuangwei, Yuanshan, Zilien, Changling, Peilung and Sungluo as well as those on the right bank such as Nioudou, Dunglei, Malun #2, Malun, and Malun #1 in the total length of 21,661 meters. The existing structures of flood wall of the creek system were found partially collapsed, hollowed out, and material deterioration due to long years of weathering effect and struck by typhoon and heavy rains. Especially, after the erosion impact brought by Typhoon Saola in 2012, serious damages were done and the safety needs to be evaluated. In order to look for effective maintenance and reinforcement initiatives, we conduct this safety evaluation and analysis project and propose the initiative for improvement for the reference of future management and maintenance.
The project consists of two parts: dike inspection and data collection, analysis, and compiling. The former includes: on-site investigation of dike structures to cover the scope of two banks of Lanyang Creek. In three on-site visits, 50 damaged parts were identified. After visual inspection on damages, 48 sites need to be improved by this project and two need to be observed. Damage types are mainly caused by cracks, about 34 sites, followed by six pothole damages. Additionally, the non-destructive testing is conducted on erosion with the ground-penetrating radar to complete the measurement length of 35,937 meters. Results show the mild erosion level of dikes at the length of 136 meters as well as no intermediate and serious level of erosion. Furthermore, through the cross-examination of radar testing, impact-echo method, rebound hammer method, and core testing, similar empirical proofs were identified. Thus, this project utilized ground-penetrating radar to inspect dike structures to fully understand the current state of them.