圖書典藏及影音數位平台

曾文水庫位於嘉義縣大埔鄉曾文溪主流上游，為台灣庫容最大之水庫，兼具灌溉、給水、發電及防洪功能。然自民國98年遭受莫拉克颱風侵襲後，水庫上游集水區邊坡崩坍嚴重，進而加速水庫淤積惡化之情形，並嚴重影響水庫容量與防洪運轉操作。為使本水庫後續相關治理計畫能維持水庫營運功能、保育上游集水區水域環境及穩定水庫供水能力，本局依據「曾文水庫水力排砂等可行性規劃調查設計」計畫之評估成果，辦理曾文水庫永久河道放水道改建防淤設施工程，以期維持水庫庫容及延長其營運壽命。 本工程係將水庫既有何本閥改建為射流閘門，出口端1號導水隧道段混凝土結構體之安全性，對防洪防淤功能之影響至鉅。由於隧道結構物屬於地下長條形結構，具有封閉性、複雜性和不確定性等特性，加上洞內空間有限，不易進行維修與補強，相對地所需維修與補強費用將更形浩大。本工程於設計階段時即納入劣化防治觀念，隧道下半部與消能墩構造採用耐磨混凝土材料設計及預埋數位磨耗感測元件，以期延長隧道生命週期。但由於1號導水隧道於排砂操作時之平均流速約20-30 m/s，此高速夾砂水流將預計對1號導水隧道內混凝土結構物與消能墩造成磨耗。基於1號導水隧道內人工觀/檢測與現有儀器檢測(如3D雷射掃描儀)均須於排砂操作停止後方能進行，且耗時較久，對於隧道內結構物的磨耗情形不易掌控，甚至錯失修復時機。基於上述原因，本工程於施工階段即預埋之數位磨耗感測元件，進而利用它即時進行監測，即可在不影響排砂操作之情況下，即時準確了解隧道內混凝土結構物的磨耗情形，監測結果與排砂操作相關資料進行分析，可適時制定修復計畫維護其安全性，同時可提供後續設計與材料應用之參考依據，爰擬辦理本委辦案。

The main work scope of this project is that all structures above the water surface of the hydropower tunnel (including the inverted arch, the side wall and the first tailrace, etc.) within the tunnel from the energy dissipating ring to the second tailrace of the downstream. This year, the water diversion tunnel newly established the first tailrace in front of the energy-dissipating pier and repaired the restorative pool that complements the energy-dissipating ring to the first tailrace. The lower 1.5m height of the first tailrace is covered by A36 (16mm) steel plate, the upper part is 5m in total height of the concrete structure. The static pool and side wall are repaired with concrete with designed strength of 450 kgf / cm2. Tail threshold elevation 119.113m and 115.83m, the horizontal distance between the two about 37 meters. In response to the June-August typhoon and typhoon Nesat and Haitang, the Zengwun Reservoir Management Center (106) conducted 1 June, June 14-30 and July 31-August 1 respectively Water diversion tunnel drainage operation, put the discharge is 50 cms, the total discharge were 756 * 104 m3, 396 * 104m3 and 576 * 104m3, put the water turbidity 225-2073 ppm and57-96 ppm. During the implementation of the project, a total of three-dimensional laser scanning in the No. 1 water guiding tunnel was conducted three times, the guided wave and the precision resistance concrete were tested for wear for three times, the first sill was tested for ultrasonic wave abrasion three times, the pumping operation was performed for three times, Concrete layer wear view / test 4 times and other on-site operations. According to the contrast map of three-dimensional laser scanning, it is found that the depth of wear of most of the surface layers is very small after the steel structure (the first lower part of the tailrace) and the concrete structure in the water guiding tunnel have been drained, and the results of the three scans Nesting, the difference between the amount of error values fall within 5mm reasonable range. In addition, the team developed by the project and applied to the detection of concrete abrasion ultrasonic wave guide and precision resistance wear test, the results also show that after two draining, floor depth of abrasion of concrete are less than 0.3 mm, while the first At the end of the sill plate, the wear amount of each point is less than 0.03 mm. Comparing the above two measurement results, ultrasonic guided wave measurement results than the resistance wear test results to be stable, and consistent, so follow-up testing can be guided by ultrasonic guided wave method, the precision resistance wear detection device is auxiliary. In the current year, the No. 1 water guiding tunnel did not show any significant wear and tear on the structure. However, after the drainage on 106/06/14-16 (discharge of 50 cms and total discharge of 756x104 m 3), it was located at the left of the upstream of the first tail threshold A pothole of about 250 cm in length, 120 cm in width and about 40 cm in depth was found, and the lower reinforcement had been exposed. A width of about 0.3-0.1 cm was also found along the surface of the steel plate and the concrete interface below the first tail wall crack. At 106/06/26, the contractor filled the concrete with 630 kgf / cm2 of concrete at the bottom of the damaged area to a thickness of 30 cm and repaired 10 cm of the thickness with epoxy resin mortar. After the PRO drained water again (releasing 50 cms and discharging 975 * 104 m3 in total), it was observed that there was no obvious wear on the left repair site upstream of the first tail threshold. As for the discharge water condition of No. 1 water guiding tunnel in the year of 106, the flow rate and flow regime are the main causes of the abrasion of the wear-resisting layer concrete. In the choice of materials to be repaired, the first tail-rocker water-resistant wear-resistant material can be clad with steel but the interface between the steel and concrete should be strengthened during construction; otherwise, high-strength concrete (630 kgf / cm2) is another viable option . The floor and the side wall in the event of a small area of wear pits, epoxy mortar repair, large-area repair is still mainly high-strength concrete is better. As to the concrete structure of the floor and the side wall between the downstream of the first tailrace and the second tailrace, it is suggested that the concrete can be repaired when the water diversion tunnel is completely repaired, and it is more economical to repair it with high-strength concrete.