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IS 11105 (2004): Design and Construction of Tunnel Plugs -

Code of Practice [WRD 14: Water Conductor Systems]

“!ान $ एक न' भारत का +नम-ण”

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“Invent a New India Using Knowledge”

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है”
ह
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“Knowledge is such a treasure which cannot be stolen”
 IS 11105:2004

Indian Standard
DESIGN AND CONSTRUCTION OF TUNNEL
PLUGS — CODE OF PRACTICE
(First Revision) q

ICS 93.16

G BIS 2004

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002

August 2004 Price Group 5

 ?!
!;

Water Conductor Systems Sectional Committee, WRD 14

FOREWORD
This Indian Standard (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by
the Water Conductor Systems Sectional Committee had been approved by the Water Resources Division Council.
Diversion tunnels are constructed to divert water of a river during construction stage of a dam. These tunnels
would need to be suitably plugged after the utilization of diversion works. The tunnel plugs resist the entire
unbalanced water pressure and transfer it to the surrounding rock. The seepage/leakage is kept to a minimum
manageable quantity.
To facilitate construction, adits are provided at one or more intermediate points of long tunnels. These adits have
to be suitably plugged before commissioning of the tunnels.
This standard was first published in 1984. This revision has been taken up to include construction aspects of the
tunnel plugs to make this standard comprehensive.
There is no 1S0 Standard on the subject. This standard has been prepared taking into consideration the practices
prevalent in the field in India.
The composition of the Committee responsible for formulation of this standard is given at Annex A.
For the purpose of deciding whether a particular requirement of this standard is complied with, the final value,
observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2:1960
‘Rules for rounding off numerical values (revised)’. The number of significant places retained in the rounded off
value should be the same as that of the specified value in this standard.

.“
 IS 11105:2004

Indian Standard
DESIGN AND CONSTRUCTION OF TUNNEL
PLUGS — CODE OF PRACTICE
(First Revision)

1 SCOPE intersection point of the diversion tunnel with the

vertical/inclined shaft, water conductor tunnel, etc.
1.1 This standard covers design and construction
Additional concrete may be required to be placed
aspects of tunnel plugs including keys, concreting,
for necessary hydraulic profile at the junction (see
grouting and cooling of concrete.
Fig. 1).
1.2 This standard does not cover the criteria for
4.2 For plugging construction adits, solid concrete
suitability or otherwise of providing solid concrete plug
plugs shall be provided at their junctions with main
or concrete plug with gated access for facilitating
tunnel. Gates if provided, shall be as close to the tunnel
inspection.
as possible to cause minimum hydraulic losses. It shall
1.3 This standard does not cover design of adit section, open inside the tunnel so that water pressure shall force
structural design of gate and its recess in the body of closure and sealing of gates (see Fig. 2).
the plug,
5 TYPES OF PLUGS
2 REFERENCES
Plugs are mainly classified as:
The following standards contain provisions which
a) Solid concrete plug (see Fig. 1); and
through reference in this text, constitute provisions of
this standard. At the time of publication, the editions b) Gated plug (concrete plug with gated opening,
indicated were valid. All standards are subject to see Fig. 2).
revision, and parties to agreements based on this
standard are encouraged to investigate the possibility 6 CONSTRUCTION FEATURES OF THE
of applying the most recent editions of the standards CONCRETE PLUG
indicated below: 6.1 Wedge shaped keys are generally provided for
IS No. Title better plug action.
456:2000 Plain and reinforced concrete — 6.2 Keys shall be provided in rock/concrete interface
Code of practice ~ourth revision) and within concrete to ensure effective plug action by
457:1957 Code of practice for general providing adequate bearing of the plug concrete on
construction of plain and reinforced the tunnel lining or plug concrete/tunnel lining on the
concrete for dams and other massive surrounding rock. The keyways in the tunnel lining
structures may be filled up with lean concretelwood packingl
5878: Code of practice for construction of masonry to ensure smo@h flow of water during
(Part 7) 1972 tunnels conveying water: Part 7 diversion stage and this shall be removed prior to the
Grouting concreting of the plug.
14591:1999 Temperature control ofmass concrete
for dams — Guidelines 6.3 Keyways provided in the fust stage plug concrete
shall be designed for anticipated horizontal thrust.
3 MATERIAL Keyways thus provided shall be filled up with the
Plain and reinforced concrete/work shall conform to material given in 6.2 so long as the tunnel is used for
IS 456. restricted flow purposes.
6.4 The solid concrete plug may be provided in
4 LOCATION
stages where required from operational/functional
4.1 For permitting utilization of diversion tunnels as requirements for diversion tunnels (see Fig. 1). For
spillway tunnels, outlet tunnels, tail race tunnels, etc, ensuring proper bonding between existing and
the plugs shall be placed immediately upstream of the subsequent stages of concrete chippinglroughening of

1
IS 11105:2004

I.Ll

X-J

v- C.L. OF TUNNEL

LEGEND:

~ INITIALLINING SECOND STAGE

E
CONCRETE CONCRHE

SECTION X=X
~ SECONDSTAGE
CONCRETE

FIG. 1 TYPICALSECTION(SHOWINGCONCRETEPLUG IN STAGES)

2
 /- C.L.OF TUNNEL
C.L.OF ADIT
L
l-—------ -—-—o—-—- =-4 PLUG CONCRETE I.
4- (2ND STAGE) 7(

INI
(1

C.L

----%--
.
<
w
C.L. OF ADIT
1

ENLARGED
1

I SECTION X -X
PlpAN

FIG. 2 PLAN SHOWINGGATEDPLUG

..
N
0
0
4A

--d .-J
1S 11105:2004

existing concrete should be carried out along with 2 Values of permissible shear and frictional resistance shall be
validated where required at site.
provision for suitable dowels.
6.5 The reinforcement of the tunnel lining shall be so 7.2.2 It is preferable to provide the whole length of
placed that this does not get damaged and hinder during plug in one block without arty construction joint.
the chipping of concrete keys.
8 DEPTH OF KEYWAYS
6.6 The length of concrete plug in the tunnel if
provided, without keys will depend mainly upon 8.1 Key in Concrete/Rock
frictional resistance offered by the surrounding initial The depth of key maybe calculated from the average
concrete or rock and bearing on the rock depending bearing stress in concrete/rock from the following
upon shape of the plug. formula. The permissible stresses in concrete shall be
6.7 Adequate provisions shall be made for dewatering in accordance with IS 456. In many cases the stresses
during construction. in concrete will govern as rock would be generally
stronger than concrete.
6.8 To facilitate grouting a gallery may also be left in
the plug wherever required. Hydrostatic force on the plug
Average bearing =
7 DESIGN OF PLUG stress Effective projected bearing
area .-%
7.1 Design Head
NOTES
7.1.1 Plugs in the tunnel are designed for the maximum
1 Effective projected bearing area shall be assumed 75 percent
reservoir level with no flow or minimum flow in the of the total projected bearing area of the keys to allow
tunnel. imperfections in grouting.

7.1.2 Allowance shall be made for increase in water 2 The depth of any key where feasible shall not be less than
450 mm.
head in reservoir due to any rare situations like wave
build up, surge and water hammer effects, if applicable, 9 GROUTING
in case of sudden stoppage of flow in the tunnel.
9.1 General
7.2 Plug Length
9.1.1 Grouting is required to improve the quality of
7.2.1 The length of the plug shall not be less than the the rock by filling the fissures/voids of the rock
excavated diameter of the tunnel. The overall length of surrounding the plug. This shall also be done to ensure
the plug may be increased to keep an allowance for seals better shear friction.
at the near ends. The plug length maybe calculated based
on any of the following formulae as applicable: 9.2 Types of Grouting
Hydrostatic force on the 9.2.1 Following are the two types of grouting:
plug due to water head
a) Length of the plug > a) Consolidation grouting, and
Permissible average
shear stress x PerimeFer b) Contact grouting.
of tunnel section
9.2.1.1 Consolidation grouting is done to improve the
Hydrostatic force on the
plug due to water head quality of bearing rock in the vicinity of plug and to
b) Length of the plug 2 reduce leakage at that location. In poor rocks,
Frictional resistance per consolidation grouting is done to make good any fissures
umt length of the plug
in the rock which may either be existing previously or
Hydrostatic force on the caused during tunnel driving. Consolidation grouting
plug due to water head also reduces the possible leakage through the rock.
c) Length of the plug 2 Consolidation grouting of the rock surrounding the
Frictional resistance of
plug shall be done prior to the placement of the plug
plug and shear resistance
of anchors per unit (see Fig. 3).
length of the plug 9.2.1.2 Contact grouting is low pressure grouting
NOTES through shallow holes. Contact grouting shall be done
1 Value of permissible average shear stress/shear friction to fill any cracks developed at the interfaces on account
between the plug and surrounding concrete/rock shall allow of shrinkage of concrete and to ensure better shear
for any imperfections in contact grouting between the phrg
friction and prevent excessive leakage along the contact
and the tunnel lining. Conservative values with ample safety
factors shall be considered. ofplug concrete and rockhunnel lining. It shall be done
.
4
 1S11105:2004

C.L. OF ADIT

I/
CONSOLIDATION
T GROUT HOLES

PLUG CONCRETE
/ INITIAL LINING
.
●

s- KY /i CONCRETE

“q
f;
I
FIG.3 TYPICAL SECTION(SHOWINGCONSOLIDATION
GROUTING)

from the outer ends of the plugs by means of system 9.2.1.3 In case of gated plug, contact grouting may
of supply, return and vent headers embedded in the also be done by direct holes from the gallery.
plug concrete. Contact grouting shall be done after 6
9.2.1.4 Grouting of rock surrounding the plug shall
weeks of concreting the plug (see Fig. 4).
conform to IS 5878 (Part 7).

42 days after

C.L, OF ADIT
/

CONTACT GROUTING
HOLEfl

INITIAL LINING
CONCRETE

FIG. 4 TYPICALSECTION(SHOWINGCONTRACTGROUTING)

5
IS 11105:2004

9.2.1.5 In case of excessive leakage grouting using be done monolithic with the lining of main tunnel.
micro cement and/or chemical grout shall be done to Fig. 6 shows main tunnel lining of the plug access
achieve the desired result. portion (supported on the rectangular frame around
the access through plug).
10 COOLING OF CONCRETE
11.2 In the portion, where main tunnel lining gets
10.1 Plug concrete shall be placed at temperatures to
broken by the access opening through the plug, the
be determined based on cooling studies for concrete
tunnel invert and overt shall be anchored to the
(see IS 14591 and other specialist literature). In
existing rock, as shown in Fig. 6, so that the loads
absence of such studies plug concreting can be done
acting on the straight leg between invert and portal,
at a placement temperature of 130C. In case
and overt and portal are not transferred to the tunnel
precooking of concrete is not possible, then post-
lining.
cooling may be done by circulating chilled water
through coils of thin tubing installed on top of each 12 BLOCKOUT FOR GATE
lift of concrete (see Fig. 5).
12.1 Blockouts for embedments of gate shall be
10.2 Special care shall be taken at lift joints to ensure
suitably anchored into the plug concrete.
adequate shear resistance.
12.2 Double water seals shall be provided in the
10.3 In case of gatecl plugs, cooling of concrete may
blockout to check leakage of water through the joints
not be required, if concreting is done in stages to reduce
between the plug concrete and blockouts.
the thickness of concrete. Keys shall be provided in
first stage concrete for transferring the water head 13 CLEARANCE OF SILT IN GATE CHAMBER
which is acting on the second stage of concrete .
13.1 In case of gated plugs with access through the
11 ANCHORAGE OF MAIN TUNNEL LINING plug, there are chances of silt deposits in gate chamber
IN PLUG CONCRETE behind the gate. This deposited silt needs clearance to
avoid any difficulty in operation of the gate.
11.1 In case of gated plug, full circular shape of lining
gets broken by the access opening through the plug. 13.2 Suitable arrangements shall be provided to
The main tunnel lining would have to be supported remove the anticipated silt. This may be done by
with suitable arrangements. The lining may be injecting air/water jet under pressure through the
supported on portal and concreting of this frame shall access of plug.

C.L. OF ADIT

●...!**
F .
.
.
INITIAL LINING ,. ..;:
CONCRETE \& .: :

COOLING TUBES

PLUG

LIH LINES

FIG. 5 TYPICALSECTION(SNOWINGCOOLINGARRANGEMENT)

6
 IS 11105:2004

x
1
I

QI&lUNNEL

SECOND
CONCRE

/ \ —WI I

FIG. 6A PLAN AT JUNCTIONOF H.R.T. WITHADIT

IS 11105:2004

r ANCHORS

SHEAR STRIRRUPS -

MULTILEG SHEAR STIRRUPS J

I
SECTION X -X

FIG. 6B ANCHORAGEOF MAIN TUNNELLINING

 IS 11105:2004

ANNEX A
(Foreword)
COMMITTEE COMPOSITION

Water Conductor Systems Sectional Committee, WRD 14

Organization Representative(s)

Central Water Commission, New Delhi SW D. K. MEHTA(Chairtnaa)

Andhra Pradesh State Electricity Board, Hyderabad CHIEFENGINEER

(CIVIL)
SUPEIUNTENDING
ENGINESR
(Alternate)

Assam State Electricity Board, Guwahati CHIEFENGINEER

(CtvrL)
AoDmoNALCmEF ENGtNEER
(DES) (Alternate)
Bhakra Bess Management Board, Nangal Township, (BSL)
CHIEFENGINEER
Hlmachal Pradesh DIIWCTOR(WATERI&GULATtON)
(Mterrrale)

Central Mining Research Institute, Roorkee DR V. V. R. PRASAD

SHMANILSWARUP(Alternate)

Central Soil and Material Research Station, New Delhi DMI?CTOR

DEFOTY
DIRECTOR
(RM) (Alternate)
Central Water & Power Research Station, Pune DR I. AZAILUAH
SmuR. M. SINNARKAR
(Merrraie)
Central Water Commission, New Delhi ‘DIRSCTOR
(SSPH )
(HCD) (NW&S) (Alternate)
DSRSCTOR

Consulting Engineering Services (India) Ltd, New Delhi SHRSV. K. KAPUR

WIG T. K. DAS(Alternate)

Geological Survey of India, Faridabad Smr G. K. KAIMHA

Smu D. N. BHMTACHARVYA
(Alternate)
Himachal Pradesh State Electricity Board, Sundernagar CHIEFENGINEER
(DESIGN)
SUPERUVtENDING (Alternate)
ENGINEER

Irrigation Department, Govt of Haryana, Chandigsrh Cr+mFENGINEER

(CANALS)
s UFEMNTSNDING (CDG) (Alternate)
ENGINEER

Irrigation Department, Govt of Maharashtr4 Nashik SUPERSNTSNDING

ENGINEER
(Alternate)
EXSCLMVEENGINEER

Irrigation Department, Govt of Punjab, Chrmdigarh CrrrEF ENGINEER

(CIVIL)
SUPERINTENDING (SCC) (Alternate)
ENGSNEER

Irrigation Department, Govt of UP, Roorkee CNJSFENGINSSR

(DE.SIGN)
(Alternate)
INGENGINEER
suPmNTsNLl

Irrigation Department, Govt of Kamatak& Gulbarga Dktrict CsirEF ENGINEER

(Afternate)
DEFUrY CmF ENGINEER

Jaiprakash Indust;es Ltd, New Delhi Smu D. G. KADKADB

Smu NARENDSMStkGH(Alternate)

Karnataka Power Corporation Ltd, Bangalore CmEF ENGINESR

(CrvrL DESIGN)
SUFESUNTENDING
ENGINEER(Ahernafe)
Kerala State Electricity Board, Thimvanaothapuram DSPUTYCrirEFENGSNEER
(CrvrL)
Nathpa Jhrrkri Power Corporation Ltd, New Delhi DIRECTOR
(CtVIL)
SmuR. K. SHARMA
(Alternate)
National Hydroelectric Power Corporation Ltd, Faridabad Smu V. K. GUPTA
(Alternate)
Smu SATYANARAYAN

North Eastern Electric Power Corporation Ltd, SIrillong Srmr A. C. GoSWAMI

SHFO UTPALBORA(Alferrrate)

Public Works Department, Govt of Tamil Nadu, Chennai Smu M. DrrRAmAI

9
IS 11105:2004

Organization Representative(s)

R.J. Shah & Co Ltd, Mumbai Sma S. M. SHAH

Rashtrya Pariyojana, Nirman Nigam Ltd, New Delhi Smu S. V. PATWARDHAN

SHMR. C. RASTOGI
(,4/fernate)

Tamil Nadu Electricity Board, Tamil Nadu CHSEPENGINSER

(JiYDROPROJECT)
SUPEMNTENO
tNGENGINEER(Alternate)

Tehri Hydro Development Corporation Ltd, Rlshikesh SHRIG. M. PRASAD

SrmrSHAILENDRASINGH(Alterrraie)

TEXMACO Limited, Kolkata Smr S. R. SINHA

SHIUSum BANERJEE(Ahernafe)
Water & Power Consultancy Services (I) Ltd, New Delhi Smu P. L. DIWAN
(Alternate)
SHSUA. P. CHOWDHURY

Water Resources Development Centre, Roorkee DR NAYANSHARMA

DR B. N. ASTHANA
(Alternate)

BLS Directorate General SHru S. S. Smn, Director & Head (WRD)

[Representing Dkector General (Ew#icio)]

Member-Secretary
SHRIMATI
ROSY DHAWAN
Joint Director (WRD), BIS

10
 f

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This Indian Standard has been developed from Doc : No. WRD 14 (274).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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