圖書典藏及影音數位平台

阿公店水庫（以下簡稱本水庫）位於高雄市燕巢區境內，係匯集阿公店溪上游支流旺萊溪及濁水溪之水量而成。本水庫自民國42年興建完成迄今已營運50年有餘，為解決本水庫日趨嚴重之淤積、供水及滯洪空間不足等問題，並繼續維持本水庫防洪、灌溉、公共給水等多目標功能，因此本水庫自民國86年起進行更新改善計畫，至民國94年完工，為台灣舊水庫再造的最佳案例。本水庫原為一防洪為主要目標之水庫，為確保水庫蓄水及營運期間壩體之安全及穩定，以提供水庫下游民眾生命財產之安全保證，因此利用大壩埋設之監測儀器，於水庫營運期間持續辦理監測，並對大壩進行定期或不定期安全檢查，以維本水庫營運期間之壩體安全性。

Abstract I. Introduction Agongdian Reservoir is located at Yanchao District of Kaohsiung City. It has been operated for 61 years since its finish in 1953. In order to assure the safety and stability of dam body during water reservation and operation, regular or irregular safety inspection is carried out every year. Its results will be used as the reference for assessment of safety, to maintain the safety of dam body. The main items include dam safety monitoring analysis, dam safety inspection, dam behavior and safety assessment, operation review of safety monitoring instruments and maintenance of monitoring instrument system. Meantime, the inspection results and recommendations in previous two years are collected, to understand and grasp the performance and behavior of dam. II. Basic Information of Agongdian Reservoir and Relevant Monitoring Instruments The basic facilities of Agongdian Reservoir dam include the dam, overflow tube, intake, flood discharge route and water channel etc. The safe monitoring instruments include pore pressure transducer, automatic water gauge and water level observation well, water measurement weir, tilting observation tube, surface settlement point, and seismometer etc. III. Review of Dam Monitoring Instruments and Monitoring Results In the inspection results of Agongdian Reservoir dam in this year, 13 pore pressure transducers are damaged and one pore pressure transducer is abnormal. Other instruments are not damaged, except one automatic water gauge is abnormal. The water pressure and water level are monitored at the cross-section of 0K+280, 0k+425, 0k+700, 1k+100 and 1k+500, the measurement data do not exceed the warning line, and the fluctuation amplitude is proportional to the water level of reservoir. The data source and improvement facility for measurement data of water measurement weir should be clarified. The maximum settlement amount at settlement point of dam is 8mm. The maximum shifting amount of tilting observation tube is 9.32mm. IV. Dam Safety Inspection Work and Results Dam body: The upstream slop vegetation and block stone slope protection are good, the slope surface is stable without significant crack, slide, convex and settlement. But there are scarce pores and erosion grooves. The status of dam top is good. Only one hole found at downstream slope surface of dam. Ambient environment: 8 infiltrating points are found at 0K+475~0K+825 down reach of dam. 5 damaged points on lake ring road has already been improved in October. Overflow tube: Only water leakage found at exit gate, no damage for other parts (including bell mouth, gate door frame concrete, channel side wall, bottom board and downstream reach etc.), which are in good condition. Intake: The water supply tower, water distribution structure, and linking bridge are in good condition. Flood discharge route: There is settlement, concrete damage and crack for water inducing channel. The overflow weir is in good condition. There is concrete peeling and crack for discharge tunnel. There is slight settlement for settling basin. Renovation method: Two renovation methods are proposed for damage of flood discharge route, i. e. crack repair and concrete peeling repair. V. Assessment of Dam Behavior and Stability 1. Analysis for Safety Inspection and Monitoring Results in this Year There is no immediate influence on safety of dam, but part of instruments should be repaired. 2. Infiltrating Condition of Agongdian Reservoir Dam Sill As for infiltrating issue of Agongdian Reservoir dam sill, the water pressure measurement data and water level well measurement data are adopted to draw the distribution condition of head at dam downstream reach. The field survey data of infiltrating point are used and the geologic map is consulted to draw the possible flow direction of influent, which can be used as the planning of follow-up improvement. Synthesizing the distribution map of head for four periods, it is able to find that the water level change of the reservoir is proportional to the head of groundwater. When the water level of reservoir is higher, the influent speed is accelerated slightly, but because the dam has interception wall, so the increasing degree is limited, which will not influence the safety of reservoir. In addition, the influent direction is changed with terrain, the main direction is northeast-southwest and east-west. Consulting the infiltrating record at dam downstream reach and field check record, in order to draw the influent type. They all belong to the natural depressurized infiltration of dam sill. There is no immediate hazard to the dam. It does not have obvious sediment piling up, but there is rolling situation of sediment. It is proposed to observe continuously and take the picture and record for follow-up comparison regularly. 3. Potential Damage Mechanism of Reservoir (1) The major upstream slope slip or flushing emptily, which may cause the damage of dam body. (2) The downstream slope infiltration, which may cause the pipe surge and damage the dam body. (3) The concentrated infiltration along the interface or concrete contact surface of overflow tube, water transport pipe, and dam sill, which may cause the inside erosion or pipe surge and damage the dam body. (4) The earthquake may cause dam crack or soil liquefaction and damage the dam body. (5) The heavy rain or typhoon may cause high water pressure and cause the slip and damage of dam body. Although there is part of damage found by field inspection, the appearance meets the characteristic point. The follow-up damage may cause by other reasons, such as dam top works, rain influence, and instrument damage etc. There is no safety hazard to Agongdian Reservoir dam. In addition, this team feedbacks 6 water level observation wells, dam information system, unmanned aerial vehicle photography, overflow pipe underwater photography and dam shift measurement, the inspection results all reveal that there is no hazard to the dam. VI. Review of Monitoring Instruments and Operation 1. Full Review of Monitoring Instruments Due to long use period, unstable voltage, old and wear of dam monitoring instruments, parts of instruments is damaged. In order to assure the safe monitoring function, the damaged instruments should be replaced or repaired. But dam disturbance may be occurred during replacement, so they are scrapped directly. (1) Groundwater Level Observation (25 places) It is conducted at dam body and reservoir downstream reach, wherein the data of WLE-04 are abnormal. The instrument was replaced in December. (2) Dam Water Pressure Observation (11 places) It is distributed at the cross-section of 0K+280 (WPE02, 04, 06, 07), 0K+700 (WPE16, 18, 20), 1K+100 (WPE23, 25), and 1K+500 (WPE28, 30). In the inspection results, the sensors in WPE06, 16, 18, 20, 23 and 30 are damaged. (3) Dam Core Water Pressure Observation (2 places) It is set at downstream core wall of 0K+425 (WPE-09 and 11), to verify the water blocking effect of concrete core wall. Due to the risk for drilling hole on concrete core wall is higher, it is not recommended to add and install new one. (4) Infiltrating Water Turbidity Observation The turbidity observation instrument is not set. In addition, Mr. C. H. Wan form National Chung-Shan Institute of Science and Technology is commissioned to monitor water quality of reservoir infiltrating water, the results can be involved into the report. 2. Review of Dam Water Measurement Weir There are two water measurement weirs at Agongdian Reservoir, in which WQR-01is set at 0K+700 with infiltration and WQR-03 is set at the exit of downstream reach. The measurement value of WQR-01 is only used for reference, because its elevation is higher than infiltration route and there is infiltration at downstream reach. WQR-03 is influenced by environmental factor with five sources of water, such as livelihood sewage, irrigating water, surface runoff water, groundwater and dam sill infiltrating water. The dam sill infiltrating water and groundwater flow into the ditch normally. The WQR-03 problem is field sediment accumulation and follow-up data analysis. The short-term accumulation removal and long-term prevention and improvement can be adopted. The long-term observation and segmented measurement can be used as the improvement way of WQR-03. Keywords: Agongdian Reservoir, dam, embankment dam, safety inspection, safety monitoring.