圖書典藏及影音數位平台

曾文水庫為台灣庫容最大之水庫，亦為嘉南地區最主要之水源，兼具灌溉、給水、發電及防洪功能。然而近年來陸續在納莉、海棠、泰利及莫拉克等颱風降下超大豪雨之侵襲下，曾文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。為使曾文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，自民國101年起規劃辦理「曾文水庫永久河道放水道(PRO)改建防淤設施工程」，期藉由颱洪期間以水力排砂方式，將底層高濃度泥砂排放至下游，以降低壩前淤積高程，延長水庫使用壽命。 PRO改建防淤設施工程為提升排砂能力，原何本閥已改建為全斷面射流閘門，最大流速近30 m/s 之含砂水流自射流閘門射流(設計流量為177 cms)衝擊至消能工消能後，將迴流由消能工頂版之孔道 (0.5 m×90 m) 經1號導水隧道放流至曾文溪，當高流速含砂水流持續沖擊隧道內混凝土構造時，可預期將產生磨耗甚至損毀情形，影響結構體之安全性。因此，為瞭解及掌握PRO射流閘門執行排砂後之隧道各部位磨耗及損傷狀況，有必要在排砂操作後隨即進行隧道內混凝土構造之磨耗檢測，並進一步分析所得資料，其結果除可作為爾後PRO排砂運轉操作之重要參考外，並可據以研定適切之維護或修復計畫，確保導水隧道之營運安全，爰辦理本委託案。 曾文水庫防淤隧道工程竣工後，防淤隧道與1號導水隧道可能進行水力排砂聯合運轉操作，為確保防淤隧道與1號導水隧道聯合操作之安全，爰將防淤隧道環氧樹脂砂漿抗磨層納入檢測。

The main scope of work of this project is the No. 1 water guiding tunnel from the energy-dissipating ring to the second downstream stern, including the structures above the water surface in the tunnel (including the inverted arch, the side wall and the first stern structure), and The anti-silting tunnel epoxy mortar is from 0k+000 to 0k+800 downstream of the gate shaft section. In 2018, the No. 1 water guiding tunnel was used for the discharge of water from 0823, 0826 and 0907. It was carried out 7 times on August 23-29 and September 7-9 respectively. The discharge flow was 50-100 cms. The total number of hours was At 158 hours, the total water discharge was 3,294*104m3, the mud sand concentration was 53-2572 ppm, and the total sand discharge was 74,942T. During the execution of this project, a total of 2 three-dimensional laser scanning in the No. 1 water guiding tunnel, three times of guided wave and precision resistance concrete abrasion detection, three times of first-tail slab steel ultrasonic abrasion detection, three pumping operations, and wear resistance were performed. On-site operation such as abrasion of concrete layer/testing 3 times. The difference between the two-dimensional image comparison of 2018.09.05 and 2018.10.12 shows that the maximum difference of the point occurs near the upstream surface of the first scorpion (point number 1-4), and the difference is 23cm-26.87cm, of which the point No. 2 has the largest difference; the other difference is located between the first tail and the second tail (points 17-20), and the difference is about 15.69cm-25.02cm. For the two comparison results, the difference between the point number 2 and the point number 3 is about 05-2.6cm. Compared with the field measurement results, the difference between the three-dimensional image comparison of 2018.10.12 is close to the actual situation. The main error is the water at the scanning station. Caused. On the other hand, it was found by field observation that after the first stern, the bottom and the two side walls of the water guiding tunnel were discharged by the 0823 and 0826 heavy rains, the concrete near the bottom of the first tail sill showed large pieces of flaking damage and steel fracture, and the maximum damage depth was 27 Cm. After the 0907 heavy rain was released, the area where the concrete was peeled off was damaged, and no obvious expansion damage occurred. Based on the above inspection/observation results, the main cause of concrete failure of the water-conducting tunnel in this year is discussed. It is preliminarily judged that when the water discharge amount reaches 100 cms, the strong jet water is blocked by the first tail stern and causes eddy current at its toe to form a negative pressure. Cracks occur at the interface between the wear-resistant layer concrete and the first tail sill, which eventually leads to large pieces of concrete peeling damage and steel fracture. This phenomenon is different from the originally expected progressive concrete wear. However, this year only preliminary inferences were made based on the observations once, and this phenomenon has yet to be confirmed by subsequent observations. In 2018, the anti-silting tunnel was commissioned with water on August 20-21, and 8 sand discharge operations were carried out on August 23-29 and September 7-10. The discharge rate is 20-450 cms, the total water discharge is 9,599*104m3, the mud sand concentration is 20-3166 ppm, and the total sand discharge is 225,311T. During the execution of this project, a total of 3 anti-silting tunnel epoxy wear layer observations were observed. The main cause of the wear and tear of the anti-silting tunnel this year is the impact of the concrete block remaining on the epoxy mortar and the sliding/rolling effect. The damage includes (1) the epoxy mortar is peeled off due to cracking or poor adhesion to the underlying concrete interface; (2) the two damaged sections of the epoxy mortar are subjected to the impact of the muddy water flow, causing spalling, thereby causing two The damaged area is connected to a large damaged area; (3) the epoxy mortar and the bottom concrete interface are well bonded, and the surface has different depths of wear and scratches; (4) the epoxy mortar is hit by the concrete block or the large stone block. Cracking and spalling occur, and the adhesion of the interface in some areas is poor and the area of rupture is large.