| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 107 === Shihmen reservoir is a multi-objective reservoir with water supply、power generation、flood protection、irrigation and tourism. Due to extreme climate, the frequency of compound disasters in Shihmen Reservoir has increase in recent years. Among them, losing one-third storage capacity caused by reservoir sedimentation is more serious than others. As a result, the Shihmen Reservoir need to be operated to provide more than four times the current storage capacity per year to meet the water supply demand. The Northern Bureau of Water Resources Agency (Ministry of Economic Affairs) using diverse policy with hydraulic flushing and supplemented by mechanical dredging to extend life of reservoir, and the " Amuping sediment bypass Tunnel " will be completed in 2021, not only can improve flood control capacity, bit also can discharge 640000 sediment cubic meter per year to alleviate the siltation problem.
Shihmen reservoir sedimentation problem can be divided into the check dam of the upstream catchment area, the middle and upper reaches of the reservoir area, and the siltation of the dam front and downstream sedimentation tanks, and the report of "Amuping upstream channel silt investigation" show that the sediments diameter is gradually being small from upstream to downstream, and according to the design unit of the Amping anti-sludge tunnel, the particle size is 0.1mm as the distinction between the valuable sediment and the priceless sediment, and the percent of valuable sediment also gradually being small from the upstream to the downstream of the river. Therefore, in this study takes the Amuping sediment bypass Tunnel project as the main axis, and divides the sedimentation problem into the upstream sediment transport problem ,and downstream elimination sludge problem to analyze and suggest.
Two hydraulic dredgers will be set up after the Amuping sediment bypass Tunnel project completed, and drawout sediment will be sizing into valuable sand and priceless sand through facilities, in this study considers the physical factors affecting the operation of the concrete and operation costs, and in the rivers sections 29 and 31 can reach the maximum operating ratio of 4.5, furthermore the sensitivity analysis results have the greatest impact on the operating benefit ratio with the valuable sand price; the priceless sand is sieved and placed in the flushing pool. This study uses the SRH-2D numerical model to Simulate the situation of sediment be flushing, among, the sand transport parameters are estimated by the hydraulic model test results and the sensitivity analysis, and the boundary conditions is calculated by reservoir algorithm to simulate flushing sludge situation which be placed 7、16 and 37 days , the typhoon events in this study included typhoon Soudelor, Medem, Su Li and Sura, and all of case flushing sediment ratio up to 0.8. From the analysis results of this study, it is suggested that more than the income in the initial stage of operation can be used to invest in the dredging of the upstream catchment dam, and the scouring and flushing pool is mainly based on the silt of the sedimentation tank, so that the mechanical dredging can continue to dredge during the non-flood period. The Amping anti-silting tunnel project is used as a dredging hub in the middle of the reservoir area, and at the same time, the amount of soil sand removal in the Shimen Reservoir is increased to increase the utilization rate of the project.
|
|---|
