CEEPUS Summer Project 2014 Operation and monitoring of dams and reservoirs

Transcription

1 CEEPUS Summer Project 2014 Operation and monitoring of dams and reservoirs Contents of the report: 1.Program of the activities: - Project presentation and information - Opening lectures - Schedule of the project 2.Dam and reservoir Zhrebchevo : - Description of the dam and reservoir - Brief report on the trip 3. Dam and reservoir Pancharevo : - Description of the dam and reservoir - A separate section made by Group 1 - A separate section made by Group 2 4. Visit of the Koprivshtitsa village: - Brief information and pictures of the Bulgarian architectural treasure - Pictures of the participants in CEEPUS 2014 CEEPUS Summer Project 2014 Participants: ILIYAN, SENGUL, GEORGI, ELENA-LIANA, NIKOLA, ANDREA, DIANA, NADEJDA CEEPUS Coordinator of the network BG-0022: Assoc.Prof. Maria Mavrova-Guirguinova

2 Short term CEEPUS Project on Operation and monitoring of dams and reservoirs Program of the activities: - 07 July Arrival and accommodation in the UACEG student hostel, Sofia July Welcome at UACEG 9:00 a.m. room 205 bldg. A. 1. Review of hydraulic structures - dams and facilities. (Embankment and concrete dams. Spillways, outlets and water intake facilities). 2. Basics of technical operation and monitoring of dams and reservoirs. 3. Monitoring of horizontal and vertical displacements of a dam by use of geodetic measurements. 4. Hydrological measurements of a reservoir by use of portable hydrographic sound velocity and temperature profiler Digibars. Place of measurements: Pancharevo. 5. Cross sectional measurements of a reservoir by use of portable hydrographic system, installed on radio controlled boat. 6. Tourist walk in Sofia historic center: July Excursion on hydraulic structures- dams and reservoirs. Dam and reservoir Zhrebchevo - departure 8:00 from UACEG July 2014 Practice - departure 8:00 from Block Monitoring of horizontal and vertical displacements of a dam by use of geodetic measurements. Place of measurements: dam and reservoir Pancharevo. 8. Hydrological measurements of a reservoir by use of portable hydrographic sound velocity and temperature profiler Digibar s. Place of measurements: Pancharevo July Free time - 14 July Some calculations and drawing works of above mentioned activities at the UACEG at 9:00 a.m. 9. Presentation of the results. Discussions July Free time - 16 July Departure Lecturers: Assoc.Prof. Todor Kostadinov - Faculty of geodesy, UACEG Assoc.Prof. Maria Mavrova-Guirguinova Faculty of hydraulic engineering, UACEG

3 Zhrebchevo Dam The CEEPUS 2014 group, with the lecturers, departed UACEG at 8:00 a.m, On the road the group stopped in the cultural historic town-museum Koprivshtitsa. The Zhrebchevo dam is located 45 kilometers west of the city of Sliven, on the Tundja River. Construction of the Zhrebchevo dam took place between 1965 and 1969 with a later addition of a secondary intake point near the village of Korten. The dam and its related facilities began operation in The dam serves two purposes providing water for irrigation in the Sredna Tundja system, flood protection and regulating the flow of the Tundja River. The Zhrebchevo Dam is an embankment clay-core dam. The height of the wall is 50,50 meters, length of the crest is 791 meters, width of the crest 8,00 meters. The upstream slope is 1:2,50, downstream slope is 1:2,00. The upstream face is protected against mechanical damage (from waves) via a rock armor layer. Its thickness in the upper 18,00 meters of the dam is 1,00 meters, while in the lower parts that decreases to 0,60 meters. This measure accounts for the fact that strong wave activity is expected to be strongest in the

4 upper part of the dam, where the water level fluctuates between its maximum and minimum determined values (the maximum water level and the dead volume level, respectively). The clay core is a Slender type clay core. It is asymmetric along the vertical axis, 3,00 meters wide on top, and reaching up to 18,00 meters wide at its base. It is founded in the bedrock via an open trench cut-off, with a depth of 8,00 to 15,00 meters. The total capacity of the reservoir is m 3. Facilities, related to the dam are: Spillway on the left bank with 5 gates and a ski-jump type spillway. The chute consists of two distinct regions the first with a slope of 2,50% and a length of 120 meters, the second one with a slope of 45% and a length of 77 meters. Intake tower with a pressure tunnel for the needs of the related hydroelectric plant (Bottom outlet I). The tunnel s maximum flow capacity is 150 m 3 /sec when used as a bottom outlet). Korten intake tower with a pressure tunnel (Bottom outlet II). Zhrebchevo Hydroelectric plant. The behavior of the Zhrebchevo dam is monitored as follows:

5 Horizontal and vertical displacements are measured through a geodetic system of control markers. See figure 1 and 2. 0 ОВС2 К1 К2 К3 К4 К5 К6 К7 К8 ОВС Fig.1. Fig.1. Figure of the vertical deformation of ''Zhrebchevo'' dam from the first and the last year of measurements. (Crest) К1 К2 К3 К4 К5 К6 К Fig.2. Acsonometric scheme of deformations, Zhrebchevo dam,

6 Reservoir water level Seepage through the dam, controlled by piesometers see figure 3. Sedimentation Hydrological and meteorological monitoring ,72 мах. ВН 263, год. 1:2,5 1: Rockfill Small-sized Gravel Sandy clay Small-sized Gravel 1:2 1: : E l e v a t i o n 200 Ground Top level piesometers Water level, pies. Bottom piesom. Depression Curve Range Piquetage of piesometer 245,92 234,63 223, ,99 220,43 220, , Пз-4 Пз-3 Пз-7 220, Fig.3. Cross-section of the Zhrebchevo dam, with piesometers shown. Additionally, to insure the proper operations of the dam and its related facilities, regular and emergency surveys are carried out as follows Visual surveys are carried out daily, to facilitate the rapid detection and response to any damages to the wall and its related facilities. Damages may include the appearance of cracks; potential seepage locations indicated by wet spots; collapses along the upstream face; terrain deformities in the downstream area (such as settling and bulges); corrosion and deformation of the facilities etc. The reservoir is monitored in terms of water level, discharged quantities and the presence of debris. Emergency surveys are carried out, as outlined in Decree 13 regarding the operation of dams and related facilities. They are carried out immediately following extreme events, such as conducting a flood, following an earthquake or in case the reservoir is rapidly evacuated.

7 Pic.1. The participants in CEEPUS 2014 on Zhrebchevo dam. Pic.2. Inspecting the crest of the Zhrebchevo dam.

8 Pancharevo Dam The Pancharevo Dam is located 12 kilometers south-east of Sofia, on the Iskar river. The Pancharevo dam has several key functions. It regulates the flow of the Iskar, Egula, Bistriza and Planshtitza Rivers, serves to cover the water demands of the Kremikovtzi industrial complex and facilitates the operation of the Kokaliane Hydroelectric power plant. The lake is also a significant recreational area in the region. The Pancharevo dam is an embankment dam. The maximum height of the wall is 22,00 meters with a crest length is 307,00 meters. The upstream face is sloped at a 1:3,5 to 1:4 ratio. The downstream face is sloped at a 1:2 ratio. The upstream face is protected from the influence of waves with rock armor. Below it, as an additional measure, there is a clay core. The clay screen extends on the left bank to connect the dam to the syphon spillways and their supporting concrete wall. The concrete wall is surrounded Pancharevo Dam Layout

9 by layers of compacted clay. The dam has the following relief facilities: Valve tower and bottom outlet tunnel with a flow capacity of 210 m 3 /sec Syphon spillways with a capacity of 590 m 3 /sec and a gated spillway with a capacity of 30 m 3 /sec on the left bank. Pancharevo Dam Spillways Syphon Spillway General Design Principle

10 Pic.3. Geodetic measurements on the crest of Pancharevo dam. Pic.4. The strong hands of the geodetic measurements at the Pancharevo dam.

11 Pic.5. Velocity meter used by the groups at the Pancharevo dam.

12 A separate section prepared by Group 1 on the Pancharevo dam. 1. Main principles, method and instruments for monitoring of vertical displacements. 1.1 Main principles Vertical displacements of dams are determined at different points (benchmarks) located regularly on the crest and around the dam. Benchmarks are divided in 3 kinds (types): -observed -initial -controlled Observed benchmarks are stabilized on the body of the dam. The initial benchmarks are located near the observed but, it is possible outside the zone of deformations. Controlled benchmarks are placed always outside the deformation zone. Measurements of the vertical displacements are established periodically, as usual during the highest water level and at the time of lowest level. The first measurement ( initial cycle ) is organized before filling the lake, the next-at 1/2 filled lave etc. Vertical displacements of the observed benchmarks are calculated by use of the formula: ΔH =H H, jk k j i i i where: H and H are elevations of the benchmarks "i", measured at cycles "k" and "j". Vertical displacements are presented by use of tables and graphics Measurements Vertical measurements are established by the method of precise geometrical leveling. First, and second order with accuracy as follow: - for first order- 0.4 mm/km double run leveling.

13 - f o r s e c o n d o r d e r m m / k m S u r v

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17 1.3.Surveying instruments Optical and digital levels are mostly used for that class of measurements with appropriate kind of staffs (fig. ) Description of the places Our first visit was at Zhrebchevo Dam which is located 45 kilometers west of the city of Sliven, on the Tundja River. The dam serves two purposes: -first-providing water for irrigation in the Sredna Tundja system, and the second is flood protection and regulating the flow of the Tundja River. The second visit was at Pancharevo Dam, which is located 12 kilometers south-east of Sofia, on the Iskar River where we had done hydrological measurements of a reservoir by use of portable hydrographic sound velocity and temperature profiler Digibar S and monitoring of horizontal and vertical displacements of a dam by use a geodetic measurements Introduction In our first meet we talked about different types of dams, such as embankment and concrete dams and their main characteristics. We also talked at least about spillways,outlets and ancillary works. We can do a comparison between embankment dam and concrete dams. We must take into account the advantages and disadvantages of this types of dams. Let`s mention same advantages of the embankment dams: -the use of natural material minimizing the need to import or transport large quantities of materials. -applicability to a different foundation conditions from rock to soft soils. The most important disadvantages include damage or destruction by overtopping. Advantages of the concrete dams: -they aren`t sensitive to overtopping under extreme flood conditions. -outlet pipes are safely housed in chambers or galleries within the dam. We must build responsibility such kind of construction, because dam failure results in a catastrophic break followed by a flood wave often with considerable loss of life or property.

18 Main causes of dam failure: -excessive uplift in the foundation (inadequate or non-existence drainage) -lack of dam stability -flow in design -lack of supervision during construction -poor design -insufficient monitoring and data analysis A few examples of monitoring: -measure displacement -settlement -seepage -piezometric pressure. 2. Measurements of vertical displacements of the Dam Pancharevo For determination of vertical displacement we used an instrument named KONI 007,and two stuffs. Firstly, we identified the benchmarks on site. Than we put the instrument in the middle of the distance between the first two benchmarks, BM1 and 1. After we fixed the instrument in horizontal position, and we ensured that the bubble from the spherical level is centered, we focused the instrument toward the staff placed behind the instrument, right in the first benchmark. Than we read on the scale of the stuff the elevation. After this, we focused the instrument towards the other staff placed in the point of the second benchmark. Same steps were followed to measure the vertical displacements of the next benchmarks. When we got to the last benchmark, we started the measurements in the opposite direction.

19 Graph of elevations of the benchmarks Project: Pancharevo damlake Hydrological measurements of the Pancharevo reservoir We were getting in the boat and establish the coordinates for the first station. Then we turned on the Digibar S and the electronics are stabilizing. We lower the probe after the LED starts blinking. The LED blinking 1 times/second and that means the Digibar S is ready to be deployed in the water. Once in the water the LED will go off. The Digibar S is getting lower until it touches the bottom of the lake. Once it touches is getting upper to the surface. The measurements are stored internally in non volatile memory. We do the same for 4 stations more. After that we

20 connected the cable of the Digibar S to a computer's USB port. The Digibar S measure the time, sound velocity, depth, temperature, voltage and salinity. The measureaments help us to find out te Average Sound Velocity, the graphic between Depth and Temperature and many other graphics. Using this data we were able to construct a cross section of the reservoir in the determined location that shows the temperature distribution in depth.

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23 Graph of elevations of the benchmarks Project: Pancharevo damlake Elevation of the benchmarks H [m] D [m] 0BM Elevation of the benchmarks Legend: Initial mesurments