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1. PRESENTED BY
SOMNATH
M.TECH.(EGL),Reg.16MT000942
INDUSTRIAL TRAINING REPORT OF VISHNUGAD
HYDRO-ELECTRIC PROJECT,(THDCIL)

2. PROJECT REPORT
Content :
• Introduction to VPHEP
• Project details
• Regional Geology & Geomorphology
• Scope of present Study
• Data collection and Analysis
• Rock support arrangement
• conclusion

3. • The VPHEP is located near Pipalkoti in Chamoli distt., state of Uttrakhand
• The VPHEP is being Constructed on Alaknanda river, a major tributary of
river Ganga.
• It is a Run of River (ROR) project
• An underground power house complex has been proposed at village Haat
(79024’31’’E and 30025’31’’N), 5 km from Pipalkoti.
Introduction

4. • The Vishnugad Pipalkoti Hydro Electric Project (VPHEP) (4 x 111 MW) is being
constructed by THDC India Ltd on Alaknanda River, in Chamoli district,
Uttrakhand
• Project includes the construction of a diversion dam of 65 m height with a gross
head of 237 m.
• Estimated reservoir will have a gross storage capacity of 3.63 Million cubic m,
out of which 2.47 Million cubic m shall be live storage.
• A diversion cum spill tunnel of 10 m dia. shall divert the discharge of 725 m3/Sec
during the construction period.
• Underground sedimentation chambers, a head race tunnel(13.3 km), a surge
shaft, 02 nos. pressure shafts bifurcating into 4 No Penstocks.
• The powerhouse complex comprises of two separate underground caverns for
installation of turbines and transformers.

5. http://tehrigarhwalonline.blogspot.in/2010_07_09
_archive.html
VPHEP location
The map of India highlights the location of Uttrakhand,
where the map of Uttrakhand shows the location of the
project area near Chamoli region.
Project Location

6. LAYOUT OF PROJECT

7. Regional Geology & Geomorphology
• Project is located in the
tectonic window known
as Pipalkoti window
(carbonate suit of
Chamoli)
• Exposing lesser
Himalayan meta-
sedimentary rocks
enveloped by low to
medium grade
metamorphic rock of
higher Himalaya.
http://www.iisc.ernet.in/currsci/jul10/articles10.htm
Regional geological map of Chamoli dist., (after Valdiya)

8. • The rocks of window zone are grouped under the Garhwal Group
represented by low grade quartzitic sandstone dolomitic limestone
and slates with metabasic sills and dykes.
• The rocks of the project area is folded in a wide open regional
domal structure known as the Pipalkoti Anticline, which is
intersected by a number of faults complicating the structural setup.
Regional Geology

9. Outer
Crystallines
Helang Formation Quartz mylonites, granitic gneisses and migmitites,
garnetiferous quartz mica schist, meta basics/amphibolites
gneisses and calc-silicate gneisses
MCT Floor thrust
Garhwal
group
(lesser
Himalaya
exposed in
Pipalkoti
tectonic
window)
Gulabkoti formation Gray to faun coloured dolomitic limestone/ talc pockets
alongside the shear zone
Medium grained, light gray sericitic quartzite intruded by basic
sills/ dykes (Changed to schistose meta basics and medium to
course grained amphibolites). Quartzite alongside the thrust
turning into quartz- mylonites
Gulabkoti Thrust
Pipalkoti formation Alternate thick succession of slates and dolomitic limestone
unites.
Upper member- Thick dolomitic limestone with occasional
bands of slates.
Middle Member-Thick gray slates with occasional dolomitic
limestone beds.
Basal Member- Thick dolomitic limestone interbedded with
slates.
Jaisal fault
Outer
Crystallines
Helang Formation
(Berahi)
Quartz mylonites, granitic gneisses and migmitites,
garnetiferous quartz mica schist, meta basics/ amphibolites
gneisses and calc silicate gneisses

10. Scope of present Study:
Study of Rock Mass Rating (RMR) used as suitable condition for
construction of Tunnels at power house complex. RMR rating
parameter is used to define the rock class and its support system.
This engineering classification system, which was developed by
Bieniawski in 1973, utilizes the following six rock mass parameters:
• Uniaxial compressive strength of intact rock material.
• Rock quality designation (RQD).
• Spacing of discontinuities.
• Condition of discontinuities, given as

11. I. Length, persistence
II. Separation
III. Smoothness
IV. Infilling
V. Alteration / weathering
• Groundwater conditions.
• Orientation of discontinuities
The rating of each of these parameters are summarized to give a value
of RMR.
To apply the RMR classification the rock mass along a tunnel route is
divided into a number of structural regions, i.e. zones in which certain
geological feature are more or less uniform. The above six classification
parameters are determined for each structural region from
measurements in the field

12. Five basic rock mass classification parameter and their rating, Rock Mass
Rating System (After Bieniawski 1989)

13. Rock Mass Rating System (After Bieniawski 1989)

14. Guidelines for excavation and support of 10 m span rock tunnels in
accordance with the RMR system (After Bieniawski 1989)

15. Applications of RMR System
RMR system provides a set of guidelines for the selection of rock
reinforcement for tunnels as shown in Table 6 (Bieniawski, 1989).
These guidelines depend on factors such as depth below surface (in-
situ stress), tunnel size and shape, and method of excavation. It is
recommended in many mining and civil engineering applications to
consider steel fibre reinforced shotcrete instead of wire mesh and
shotcrete (Hoek, 2007).
RMR is also applied to correlate with excavated active span and
stand-up time, as shown in Figure (Bieniawski, 1993).
RMR can be used to obtain properties of rock mass as shown in
Table.

17. Limitations of RMR system
Output of RMR system can lead to overdesign of support systems
because it is conservative (Bieniawski, 1989). For example, the no-
support limit is too conservative and to adjust RMR at the no-
support limit for opening size effects, Kaiser et al. (1986) suggested
the following relation.
RMR (NS) = 22 ln(ED + 25)
Where NS stands for No Support and ED is the equivalent
dimension.
RMR system cannot be used reliably in weak rock masses because
it is mostly based on case histories of competent rocks (Singh and
Geol, 1999). This system is not useful for deciding excavation
method.

18. Construction Sequence
• Survey (Profile)
• Drilling (Jumbo drill)
• Charging (blasting)
• Blast
• Defusing (gas)
• Mucking (rock fragments)
• Support installations
I. Sealing Shotcrete (SRFS)
II. Rock bolt
III. Wire mesh (1 or 2 layer)
IV. Passive support (Ex. steel rib, reinforced shotcrete)
V. Active support (Ex. Lattice girder)

19. DRILLING
(ड्रिल िंग)
CHARGING
(चार्ज)
BLASTING
((विस्फोटन)
MUCKING
(म िा
हटाना)
GEOLOGIC
AL
MAPPING
(भूिैज्ञाननक
अध्ययन)
SUPPORT
INSTALLATIO
N
सपोटट
SURVEY
(सिेक्षण)
CONSTRUCTIONCYCLE
Starts

20. Joint data in power house complex
Joint set Dip amount Dip direction(N) Spacing
(cm)
Persistence
(m)
Aperture(mm)
/ Infilling
Foliation plane
(FJ/J1)
50 - 150 & 250 - 350 2900-3200 & 1100-
130o
<6-30 3-10 Tight to slightly
open / Nil
Cross joint (J2) 700 - 800 1300-1400 20- 50 3-5 Tight / Nil
Joint (J3) 700 - 800 0100 - 0350 <6-30 3-5 Tight / Nil
Data collection and Analysis
The power house complex comprises the Machine Hall, Transformer Hall, U/s Surge Shaft, d/s Surge Tank,
Main Access Tunnel (MAT), Ventilation Tunnel (VT), and Adit to TRT

21. UCS
VALUE
50-100 (MPA)
RATING
7
VALUE RATING
7
RQD 36 8 43 8
JOINT SPACING 25- 30 cm 5 45cm 5
JOINT
PERSISTENCE
4 m 2 3.5 m 4
JOINT APERTURE Less <0.1 cm 5 Less <0.1 cm 5
JOINT
ROUGHNESS
smooth 1 smooth 1
JOINT INFILLING none 6 none 6
JOINT
WEATHERING
Un-weathered 6 Un-weathered 6
GROUND WATER
CONITION
dry 15 15 15
ORIETAION
FACTOR
75-80 dip very
unfavourable(j3 is
prominent joint)
-12
Total =46RMR
Class III (41-60)
75-80 dip very
unfavourable(j3 is
prominent joint
-12
Total RMR 45
Which also class
III

22. Joint set in power house complex

23. Face-log & 3D mapping
• Facelog & 3D mapping we show actual joints and other discontinuity
how encountered in tunnel and also lithology .
• These data are kept for future reference. Used to understand
structural discontinuity and lithology condition.

24. Showing face log mapping of chainage 123.5 m. adit to surge tank bottom
Over
brakeJoints

25. Sample of 3-D Geological map

26. SFRS
Wire
mesh
Rock
Bolting
Lattice
Girder
Steel
Rib
Shotcret
e
Rock support system

27. Rock support is added to improve stability of underground opening.
Pre-geological investigation is used to reveal the main characteristics of
the rock mass surrounding the opening and a design is made to deal
with various geological conditions in the tunnel. Geological conditions
often change very rapidly on the tunnel route and that require flexible
support methods that can be quickly adjusted to the current
circumstances.
Types of supports
 Rock bolting - Rock bolting is a flexible method very commonly
used for rock support. Rock bolts are frequently used as initial
support at the tunnel face to obtain safe working conditions for the
crew and they also form part of the final rock support

28. Fig: Showing rock bolting ,Steel fibre-reinforced shotcrete (SFRS) and rock bolting
machine
Steel fibre-
reinforced
shotcreteRock
bolting

29. Steel fibre-reinforced shotcrete - Steel fibre-reinforced shotcrete (SFRS) is
mixture of cement materials with steel fibres of different sizes.
Steel ribs – steel ribs are circular, semi-circular, horseshoe (2F & 4F)
designed support made-up of steel.it is a great solution for all roofing and
wall cladding purposes.
https://www.dsiunderground.c
om/fileadmin/_migrated/pics/
DSI_steelribsupport_02.jpg

30. Steel ribs

31. lattice girder- Lattice Girders are lightweight, three-dimensional steel
frames typically fabricated of three primary bars connected by stiffening
elements. It is active type of support system.
Advantages:
• Low weight facilitates installation process
• Used in conjunction with shotcrete, lattice girders allow rapid tunnel
advancement
Table Rock support system for Power house complex
Class-II Class-III
Rock bolt
25mm dia., 190 kN, 6m & 8m alternately fully
cement grouted pre-tensioned rock bolt at 7T @
1500 c/c staggered.
25mm dia., 190 kN, 6m & 8m alternately fully
cement grouted pre-tensioned rock bolt at 7T @
1100 c/c staggered.
Shotcrete 300mm SFRS 300mm SFRS

32. Conclusions
Project is located in the tectonic window known as Pipalkoti window
(carbonate suit of Chamoli), which is highly structural disturbances
triggered by earthquakes.
Our work comprises classification of rock mass in powerhouse complex
and on class of rock mass give there suitable support system.
Rock Mass Rating System (After Bieniawski 1989) applied.
In power house rock type thick gray slates with occasional dolomitic
limestone beds.
Rock mass classified in class III (41-60)
Support system shotcrete, SRFS, wire mesh, steel ribs , lattice girder
used