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
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Evaluating permeability and groutability at the Karun
4 dam Iran using Lugeon values and grout Take
Mohammad Hosseiny Sohi1, Prof.Dr. Manfred Koch1, Dr. Javad Ashjari 2
1 Department of Geohydraulics and Engineering Hydrology, Kassel University, Kassel, Germany2 School of Geology, University of Tehran, Tehran, Iran
Contents
Introduction
Study area and dam specifications
Methodology and data
Results
Conclusions
References
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.
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.
Karun 4 dam technical specifications
Location and details of the Karun 4 dam in Iran
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.
Selected Exploratory- , line 1 and line 2 check holes in the
grouting galleries
3D view of Karun 4 dam body and grouting galleries
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).
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).
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:
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.
Results
Lugeon Permeability
Frequency distribution of Lugeon values in the different classes for
exploratory, line 1 and line 2 check holes for the left and right banks.
20 21
33
18
7
34
43
20
2 1
27
55
18
0 00
10
20
30
40
50
60
0 - 3 3 - 10 10 - 30 30 - 60 > 60
Fre
qu
en
cy %
Lugeon Values of Left Bank
Exploratory holes
Line 1 check holes
Line 2 check holes
34
41
24
16
7
56
34
9
10
48
38
10
5
00
10
20
30
40
50
60
0 - 3 3 - 10 10 - 30 30 - 60 > 60
Fre
qu
en
cy %
Lugeon Values of Right Bank
Exploratory holes
Line 1 check holes
Line 2 check holes
Results
Groutability
Frequency distribution of Take in the different classes for exploratory, line 1
and line 2 check holes for the left and right banks.