Evaluating permeability and groutability at the Karun 4 dam Iran using Lugeon values and grout Take

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Javad Ashjari 2 1 Department of Geohydraulics and Engineering Hydrology, Kassel

1 Evaluating permeability and groutability at the Karun 4 dam Iran using Lugeon values and grout Take Mohammad Hosseiny Sohi 1, Prof.Dr. Manfred Koch 1, Dr. Javad Ashjari 2 1 Department of Geohydraulics and Engineering Hydrology, Kassel University, Kassel, Germany 2 School of Geology, University of Tehran, Tehran, Iran

2 Contents Introduction Study area and dam specifications Methodology and data Results Conclusions References

3 Introduction Water leakage through the foundation and abutments of a dam which is built on limestone formations, is one of the most important challenges of the big dams construction and operation. The water- soluble carbonate structure of such limestone may lead to the development of fissures and fractures that may, eventually, expand to conduits and even caverns and caves; a process which is known as karstification (Milanović, 2004; Ford & Williams, 2007). In the present study, the permeability as the most important parameter determining water seepage of the Karun 4 dam, constructed on a limestone formation with karst potential will be presented.

4 Study area and dam specifications The Karun 4 Dam is located on the Karun River in the state of Chaharmahal and Bakhtiari, at a distance of 180 km from the State Capital of Shahrekord, in southwest Iran. It is the highest dam of Iran (230 m from foundation) and has been impounded since March 2010.

7 Karun 4 dam technical specifications

8 Location and details of the Karun 4 dam in Iran

9 Study area and dam specifications Grout Curtain To seal the dam foundation and abutments, a very large grout curtain was designed and constructed. The construction was done through the excavation of 5 series of galleries in both left and right abutments at different elevations. From inside these galleries the grouting boreholes are drilled and injected, to have an integrated virtually wall or barrier, called grout curtain against water leakage. Based on the obtained results from the exploratory boreholes, the grout curtain in two lines was designed and constructed, to sew/stitch the dam structure to the Pabdeh impermeable formation in the upstream.

10 Selected Exploratory-, line 1 and line 2 check holes in the grouting galleries

11 3D view of Karun 4 dam body and grouting galleries

12 Methodology Water pressure test (WPT) or Lugeon test Water pressure test, packer test or simply Lugeon test has been developed by Professor Maurice Lugeon (1933). A Lugeon unit is defined as one liter/minute of water absorption per meter of test length of drill hole when the water in the borehole remains at a pressure of 10 bars or 1 MPa over a period of 10 minutes (Lugeon, 1933; Houlsby, 1990; Singh and Goel, 1999).

13 Methodology Take The (grout) Take is defined as the rate of dry cement mass that is injected to the test section, divided to the length of section (kg/m) (Deere 1982).

14 Methodology Ewert Method Ewert (1985) proposed a qualitative method to interpret the relationship between permeability and groutability in the dam foundations. He classified the obtained results from different dam sites and tests in to following grouping:

15 Methodology Ewert Method Group A: large amount of Lugeon value and low grout Take indicates that water can pass through the numerous fine fissures of the rock, but the corresponding grout is not permitted. Group B: Approximately proportionality between water and Take justifies well the necessity of grouting. Group C: The small water pass versus large Take cause to the hydraulic fracture in the rock mass and shows that either the injection pressure is not proper or at all unnecessary. Group D: Low water and Take signs the sealing of area and no need no treatment.

16 Frequency % Frequency % Results Lugeon Permeability Lugeon Values of Left Bank Lugeon Values of Right Bank Exploratory holes Line 1 check holes Line 2 check holes Exploratory holes Line 1 check holes Line 2 check holes > 60 Frequency distribution of Lugeon values in the different classes for exploratory, line 1 and line 2 check holes for the left and right banks >

17 Frequency % Frequency % Results Groutability Take Values of Left Bank Take Values of Right Bank Exploratory holes Line 1 check holes Line 2 check holes Exploratory holes Line 1 check holes Line 2 check holes > > 400 Frequency distribution of Take in the different classes for exploratory, line 1 and line 2 check holes for the left and right banks.

18 Results Correlation of Lu- permeability and Take- groutability based on Ewert s method Lugeon versus Take with the four Ewert s groupings for the exploratory holes

19 Results Correlation of Lu- permeability and Take- groutability based on Ewert s method Lugeon versus Take with the four Ewert s groupings for the line 1 check holes

20 Results Correlation of Lu- permeability and Take- groutability based on Ewert s method Lugeon versus Take with the four Ewert s groupings for the line 2 check holes

21 Results Correlation of Lu- permeability and Take- groutability based on Ewert s method Frequency distribution of Lu-Take pairs in the different groups for exploratory, and line 1 and line 2 check holes for the left and right banks.

22 Conclusions The grout curtain of Karun 4 dam is constructed on the dam foundation and abutments to prevent, or minimize the water leakage from the dam reservoir after impounding. The measurements include Lugeon- and grout- Take values of exploratory-, line 1 and line 2 check holes of the grout curtain. Totally, data from 64 selected boreholes are used to study the relation between Lugeon (Lu) permeability and groutability (Take) and, based on the values of these two variables, classified into four groups, following Ewert s methodology. The results indicate that the implemented grout curtains can seal leaking, as Take is lower than 50 kg/m in more than 90% of the boreholes the requirement for efficient grout Take -, although there are still areas with medium Lugeon values, i.e. data in Evert s class A.

23 Conclusions The Lu- values indicate that the permeabilities of the right bank are generally lower than those of the left bank. This can be explained by the geological characteristics underneath the dam of the Asmari formation (AS1) subunits. Nevertheless there is still some scattering of Lu-Take pairs into Evert s A- group, which means that water leakage exists at these locations. The technical solution would be to allow the extra water to seep through a drainage curtain.

24 Related and Ongoing studies The seepage analysis through the drainage curtain is the topic of the presented study of the authors as Poster in the Meeting: Monitoring of the seepage controlling system of the Karun 4 dam in Iran Furthermore, a numerical groundwater flow model is needed, to get a more comprehensive and quantitative picture of the water flow seepage through the dam foundation and abutments, which is the ongoing study of the authors

25 An example of the groundwater flow model results Code: CFP for Modflow 2005 GUI: Molde Muse USGS

26 References Azimian A, & Ajalloeian R (2013). Comparison between Lugeon with Secondary Permeability Index obtained of Water Pressure Test in Rock Masses. Electronic Journal of Geotechnical Engineering, Volume 18. Barton N, Bandis S, & Bakhtar K (1985). Strength, deformation and conductivity coupling of rock joints. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Volume 22, Issue 3, pp Berhane G, & Walraevens K (2013). Geological challenges in constructing the proposed Geba dam site, northern Ethiopia. Bulletin of Engineering Geology and the Environment, Volume 72, Issue 3-4, pp Bonacci O, & Roje-Bonacci T (2008). Water losses from the Ričice reservoir built in the Dinaric karst. Engineering Geology, Voume 99, Issue 3, pp Deere DU (1982). Cement-bentonite grouting for dams. ASCE, Geotechnical Engineering Specialty Conference on Grouting, New Orleans, pp Ewert, FK (1985). Rock Grouting with Emphasis on Dam Sites. Springer Berlin Heidelberg. Fell R, MacGregor P, Stapledon D, Bell G, & Foster M (2015). Geotechnical engineering of dams. 2nd edition, CRC Press. Ford D, & Williams PW (2007). Karst hydrogeology and geomorphology. [Rev. ed.]. Chichester, England, A Hoboken, NJ: John Wiley & Sons. Foyo A, Sánchez MA, & Tomillo C (2005). A proposal for a Secondary Permeability Index obtained from water pressure tests in dam foundations. Engineering Geology, volume 77, Issue 1-2, pp Gurocak Z, & Alemdag S (2012). Assessment of permeability and injection depth at the Atasu dam site (Turkey) based on experimental and numerical analyses. Bulletin of Engineering Geology and the Environment, Volume 71, Issue 2, pp Haghnejad A, Ahangari K, & Noorzad A (2014). Investigation on Various Relations Between Uniaxial Compressive Strength, Elasticity and Deformation Modulus of Asmari Formation in Iran. Arabian Journal for Science and Engineering, Volume 39, Issue 4, pp

27 References Azimian A, & Ajalloeian R (2013). Comparison between Lugeon with Secondary Permeability Index obtained of Water Pressure Test in Rock Masses. Electronic Journal of Geotechnical Engineering, Volume 18. Hosseiny Sohi SM, Koch M, Ashjari J (2014). Construction Effects of the Karun 4 Dam, Iran, on the Groundwater in the Adjacent Karstic Aquifer. ICHE 2014, Hamburg - Lehfeldt & Kopmann (eds). Houlsby AC (1990). Construction and design of cement grouting. A guide to grouting in rock foundations. New York, Wiley (Wiley series of practical construction guides). Kocbay A, & Kilic R (2006). Engineering geological assessment of the Obruk dam site (Corum, Turkey). Engineering Geology, Volume 87, Issue 3, pp Lugeon M (1933). Barrages et Geologie. Dunod, Paris Mahab Ghods Consulting Engineering Co. (2002). Final engineering geological report (phase 2). Karun 4 dam project. Mahab Ghods Consulting Engineering Co. (2010). Final excavation and injection report of the Karun 4 dam grout curtain. Sadeghiyeh SM, Hashemi M, & Ajalloeian R (2013). Comparison of Permeability and Groutability of Ostur Dam Site Rock Mass for Grout Curtain Design. Rock mechanics and rock engineering, volume 46, Issue 2, pp Turkmen S, Özgüler E, Taga H, & Karaogullarindan Talip (2002). Seepage problems in the karstic limestone foundation of the Kalecik Dam (south Turkey). Engineering Geology, Volume 63, Issue 3, pp Uromeihy A, & Barzegari G (2007). Evaluation and treatment of seepage problems at Chapar-Abad Dam, Iran. Engineering Geology, Volume 91, Issue 2, pp Uromeihy A, & Farrokhi R (2012). Evaluating groutability at the Kamal-Saleh Dam based on Lugeon tests. Bullten of Engineering Geology Environmental, Volume 71, Issue 2, pp Yang, ChP (2004). Estimating cement take and grout efficiency on foundation improvement for Li-Yu-Tan dam. Engineering Geology, Volume 75, Issue 6, pp 1 14.

28 Thanks for your attention!

29 Contact S. Mohammad Hosseiny sohi Ph.D. Candidate in Civil Engineering Department of Geo-hydraulics and Hydrology Engineering Faculty of Civil- and Environmental Engineering University of Kassel Kurt-Wolters-Straße Kassel, Germany

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