1
109
86 95
1. 2.
3. 4. 5.
6.
7.
8. ( K4) 9.
2
0k+280m 0k+425m 0k+700m 1k+100m 1k+500m
( )
( ) ( ) (
) ( ) ( )
EL.28.03~EL.37.18m 1,477.90mm
5 22 302.7mm 11
PGA 21.282gal PGV 1.211cm/sec 109 5 25
72cms 1
1.
109 0.5cm/
0.1cm/ (
1.0cm/ )
2.
108 7k+475m
2k+467 6k+725 6k+890 8k+940
110
3
3.
4 7
15 3 11 26
1 5
(109 ) 60
4.
3 BH03~BH04
5.
2 10
6. ( K4)
4 K4 5
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In 2020, safety inspection and monitoring of Agongdian reservoir was entrusted by Southern Region Water Resources Office, WRA, MOEA(WRASB), and it was executed by Liming Engineering Consultants. The purpose of this project is by using the monitoring instrument to continuous monitoring during the operation of the reservoir and carry out the regular or irregular inspections of reservoir to maintain the safety of reservoir during the operation. The work content and summary of key content are the following:
a. The overview and the work content
The Agongdian reservoir is the reservoir which is built for preventing flood and solve the issues of sediment accumulation, irrigation, domestic water supply, and inadequate freeboard. At the same time, it can achieve the target functions of Flood control, irrigation and public water supply. The updated improvement project started from 1997 and finished in 2006, which is the best case of old reservoirs re-building in Taiwan. In order to ensure the residents living downstream of the dam are safe and secure. During the project progress, doing safety inspection and monitoring analysis with the related equipment. This project include the following works: 1. Dam safety monitoring analysis. 2. Dam safety inspection. 3. Trans basin waterway safety inspection. 4. Dam behavior and safety evaluation. 5. Review of the operation and maintenance of safety monitoring devices. 6. Automatic water level real- time transport system at downstream seepage area of dam. 7. solar system shore anchor monitoring analysis. 8. Inclinometer installation at downstream seepage area of dam. 9. Work Briefing, report writing and printing.
b. Facility basic information and annual overview
The main civil structures at Agongdian reservoir are include the main dam, spillway, intake works, and the interbasin transfer spillway. The monitors at Agongdian reservoir are spread across five sections: 0k+280m 0k+425m 0k+700m 1k+100m 1k+500m. The dam safety and stability can be long-
content includes 1. The water pressure inside the dam (piezometers). 2. The
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water level inside the dam and downstream (groundwater gauges). 3. The dam seepage (seepage weir). 4. The lateral displacement of dam(inclinometer). 5 The dam settlement (settlement observation point). 6. The dam seismic intensity (seismograph).
In 2019, the dam water level was between EL. 28.03m~ EL. 36.97m, the annual accumulated rainfall is 1,452.8mm. The maximum daily rainfall is 302.7mm on May-22rd. The seismograph recorded 11 earthquakes, the maximum PGA value is 21.282 gal, the maximum PGV value is 1.211 cm/sec.
c. Project result
According to the various monitoring instrument and inspection, the result is the following:
1. Dam
The change in the total head which in the dam body and dam foundation is regular and stable. All the monitors at the dam sections are both below the warning value. Therefore, the dam seepage is considered as reasonable. During previous year, the vertical settlement in dam stabilization period at upstream is 0.01cm/year, and the vertical settlement in dam stabilization period at downstream is 0.31cm/year. Neither of the settlement on upstream and downstream exceed the allowable value. (The vertical settlement in dam stabilization period should less than 1.0cm/year.) The vertical settlement demonstrates a stable tendency. The dam structure, upstream slope and downstream slope are overall good. There are no wide range sliding, leakage, settlement and damage.
2. Trans basin waterway
The abnormal conditions of spalling tunnel lining, exposed deformed bar, crack, seepage and efflorescence already exist form the past. There is no significant difference from last year results. The heaving inverted lining at sta.7k+475m is affected by the shear zone. The exposed deformed bar at sta.2k+467, 6k+725, 6k+890, 8k+940 are the relatively severe area, but there are no signs of being affected by external forces on lining. It might be caused by the aging of the material (Neutralization of concrete).
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3. Review of the operation and maintenance of safety monitoring devices Currently, there are 8 sets of pore water pressure cell, 10 sets of self- recording groundwater gauges, 8 sets of groundwater gauges, 3 sets of seismograph, 11 sets of inclinometer, 26 sets of settlement observation point, 1 set of seepage weirs and 5 sets of data recording devices, and it is enough to judge the dam safety.
4. Automatic water level real-time transport system at downstream seepage area of dam.
The automatic water level real-time transport system at water well BH- 03~BH-04 was finished in this year. The onsite water level data can be transport to the monitoring room in real-time and show up the water level data on the monitor screen. The related monitoring and analysis results are
automated are recommend to continue the achievement of this project.
Considering the result of this report, unautomated water level wells are proposed to be upgraded.
5. Safety monitoring devices of Solar system Shore anchor.
The Safety monitoring devices of Solar system Shore anchor was finished and Perform initial measurement operations in March this year.
And perform measurement again in October. The analysis results are presented at Chapter 3.
6. Inclinometer(No.K4) at downstream area of dam.
The Inclinometer(No.K4) installation was finished in April this year.
And Start monitoring in May this year. The analysis results are presented at Chapter 3.
