proposal for standardization of tunnel cross section...

Proposal for Standardization of Tunnel Cross Section,

Design and Drawings in Indian Railways

Mr. Avijit Majumder, Deputy Chief Engineer /CON/Design-2/Maligaon

Mr. Koteshwar Ponnala, Deputy Chief Engineer /CON/Design-1/Maligaon

Mr. Manas Ranjan Mohapatro, Junior Engineer/CON/Design-1/Maligaon

Abstract

Indian Railway is constructing large number of tunnels all across the country

especially northern and north east regions in adverse geological conditions without

any specific guidelines on standard tunnel cross section and supporting systems. As

Indian Railways gathered lot of experience in design and execution of tunnels, it is

high time to issue directives for adopting standard practices which makes

construction methodology and design easy despite of saving lot of time and

expenditure in finalizing the design and drawings of tunnel.

N.F. Railway, Construction organization completed approximately 70,000 Rm

Tunnels by adopting NATM method with various supporting systems based on the

class of rock type. Several type of cross sections and support classes have been used

in Railways so far due to non-standardization of tunnel cross section and also

supporting systems, as a result lot of time and effort invested in finalization of design

and drawings of tunnels.

So, the authors of this paper studied all the design and drawings of tunnels finalized

in the design section of N.F. Railway, construction organization. Authors are of view

that tunnel cross section and supporting systems may be standardized and it may be

differed under special/rare cases.

1.0 INTRODUCTION

As per Indian Railway vision document, all State capitals of the North East States are

to be connected with Broad Gauge(BG) Rail Link to provide reliable transport facility

to the people of this region, accordingly Government of India sanctioned several

projects and works are in progress at various stages which involves construction of

sizable length of tunnels.

1.1 Geology of the North East Region:

The rock formation in this region is part of the relatively very young folded mountains

of Indo – Myanmar Range (IMR) of the Himalayan system. The IMR evolved as an

accretionary prism due to subduction of the Indian plate below the Myanmar plate

during the Alpine – Himalayan tecto-genesis. As a result of tectonic collision, most of

the rocks are folded and trusted with major geological structure. The rock formation

in north east region is mostly sedimentary rocks (predominantly sand stone and shale)

belong to Class-V to VIII

Fig.1: Alignment of Jiribam – Tupul - Imphal Section

Fig.2: Alignment of Bairabi - Sairang Section

In N.F. Railway, all the tunnels have been constructed by adopting methodology of

NATM (New Austrian Tunneling Method). The main principle of NATM is that

“rock mass of the surrounding tunnel is the principle load bearing component of the

tunnel” and it is stabilized by providing earth/rock anchors, wire mesh with shotcrete,

flexible lattice girder. The secondary lining is provided to achieve desired shape from

aesthetic point of view and functional requirement during service period. In this

method, maintaining the strength of the rock mass by careful excavation and

immediate application of primary supporting system is very essential during

execution. Shotcrete and rock bolts are applied immediately in the form of primary

support system after excavation of face to maintain the integrity of the rock mass and

transfer the load of loosened/disintegrated/cracked rock mass to the surrounding

undisturbed rock mass. The most important point in this method is allowing the

deformation/breathing of surrounding mass before proving the final lining after

reaching deformation @ 2mm/month.

2.0 Approach of Tunnel Support Design:

Support Design is finalized based on Rock Mass type, rock mass quality and In-Situ

stress condition expected to be encountered along the tunnel alignment as determined

by review and assessment on geo-logical and geo-technical data available.

In order to collect the geo-technical parameters and geo-logical data, A detailed

requisite investigation is to be performed to predict behavior of the rock mass

surrounding the tunnel. The rock mass is also classified according to the ‘Q’ system,

Rock Mass Rating (RMR) and Geological Strength Index (GSI).

In general, Tunnel is analyzed by using RocScience software which is numerical

analysis software based on finite element method. Cohesion value (C), angle of

internal friction (ɸ), unconfined compressive strength (qu), GSI of rock mass are the

basic input parameters required to be fed this software for analyzing and finalizing the

supporting systems.

The numerical analysis results of the software indicate that the combined system of

rock mass/support measures does not fail and system behavior remains stable. The

deformations occurring around the excavations are within the limit of the allowable

deformation tolerances corresponding to the given supporting system. The sample

output of the software is shown below.

Fig.3: Alignment of Bairabi - Sairang Section

3.0 Construction methodology:

3.1 The mined tunnel section of this region are being constructed on the principles

of New Austrian Tunneling Method (NATM).

3.2 This method is based on the concept of a cyclic sequence of excavation with

subsequent installation of a flexible primary support (outer lining) followed by

installation of secondary (final) lining, after achieving the allowed

deformation of primary lining.

3.3 The outer lining consists of:

i. Sprayed concrete, generally reinforced by wire mesh or fibres,

ii.Lattice girder or steel ribs

iii.Rock bolts those provide immediate support and stability of the

excavation.

3.4 After initial support of the tunnel, the section undergoes deformation.

However, various support systems are being placed to control the deformation.

The amount of deformation is being checked by 3D monitoring system. After

deformation reaches the certain limit and once the equilibrium is ensured,

inner lining is provided. The inner lining or the final lining provides long term

support, durability & serviceability to the tunnel.

3.5 Based on the type of earth/rock encountered during tunneling work, different

excavation sequence, type and quality of primary support element have to be

considered. The complete sequence of work from excavation to installation of

primary support is based on rock/earth class. The tunnel section of a particular

support class is made as per actual ground condition encountered at that

location during excavation.

3.6 In order to achieve effective drainage system within the tunnel section, two

longitudinal drains are provided. Apart from that, pore-water pressure

generated at outside of the tunnel is released to longitudinal drain by providing

weep holes located at drain level.

4.0 Various projects of N.F. Railway where tunneling works are in progress:

4.1 Jiribam – Tupul – Imphal New Line National Project: In this project, 44

numbers of tunnels have been constructed with a total length of 46.20 Km.

Two types of cross sections have been adopted with areas of 37.78 sqm and

39.247 Sqm. Mostly rock formation is shale and sand stone belonging to

supporting class-IV to VII.

4.2 Bairabi – Sairang New Line National Project: In this project, 23 numbers of

tunnels have been constructed with a total length of 19km. one type of cross

sections has been adopted having area of 40.46 sqm. Mostly rock formation

is shale and sand stone belonging to supporting class-V to VII.

4.3 Gauripur – Abhyapuri New Line Project: In this project, 4 numbers of

tunnels have been constructed having total length of 1.055 Km. the cross

section adopted in this section is having an area of 38.487 sqm.

4.4 Dimapur – Kohima New Line National Project: In this project, 19 numbers

of tunnels have been proposed; already 5 numbers of tunnels have been

constructed with cross sectional area of 41.55 sqm and 40.41 Sqm.

4.5 Sevok – Rangpo New Line National Project: In this project,14 Nos Tunnels

needs to be constructed having total length 38 Km.

5.0 Problems encountered during Design and Finalization of Tunnel

Drawings:

5.1 changes in cross sections for different tunnels with similar conditions.

5.2 Different Systems of primary and secondary supporting systems for the

same encountered rock classes.

5.3 Expenditure increases on Design and Drawing of Tunnels besides

consuming lot of time due to non-standardization of tunnel cross section

and supporting systems which is repetitive in nature.

5.4 Parameters and type of cross sections adopted in NFR, Construction are

shown in below in the tabular form:

Sl

No

Shape

of

Tunnel

Area of

Cross

section

in sqm.

Clear

Width of

footpath

BLT/

Ballas

ted

Provis

ion

for

Worki

ng

BCM

Water

Proofing

Membra

ne

Section

al

speed

in

KMPH

Provision

for

Electrificat

ion

Suitable up

to Degree

of

Curvature Remarks

1

Horse

Shoe 37.78 550mm

Ballast

ed No No 100 Yes 3°

2

Horse

Shoe 39.247 800mm

Ballast


Clear width of

Footpath Increase

3

Horse

Shoe 40.46 800mm

Ballast


Top Width of

ODC increase

4

Horse

Shoe 38.487 550mm

Ballast


Sectional speed

increase

5

Horse

Shoe 41.55 1248mm

Ballast

ed Yes No 100 Yes 3°

Increase of width

of footpath and

width of Ballast.

Sduitable for

BCM

6

Horse

Shoe 40.41 1065mm

Ballast

ed Yes No 100 Yes 3°

Increase of width

of footpath and

width of Ballast.

Sduitable for

BCM

5.5 The various tunnel cross sections used in NFR, Construction is shown below

Fig.4: Typical Cross section (Jiribam – Tupul section; Area: 37.78 sqm.)

Fig. 5: Typical Cross section (Tupul – Imphal section; Area: 39.247 sqm.)

Fig. 6: Typical Cross sections (Bairabi – Sairang section; Area : 40.46 sqm.)

Fig.7: Typical Cross section (Gauripur – Abhyapuri section; Area: 38.487 sqm. above Rail Level)

Fig. 8: Typical Cross section T-1 (Dimapur – Kohima section; Area : 41.55 sqm. Above Rail Level)

Fig. 9: Typical Cross section T-1A (Dimapur – Kohima section; area: 40.41 sqm. Above Rail Level)

5.6 After considering all the design parameters and provisions, an ideal cross

Section has been developed as shown below:

Fig. 10: Typical new Cross section with water proofing layer (Area: 40.400 sq. m above Rail Level; Total

Excavated area (including Invert) = 68.527sq.m

Fig. 11: Typical new Cross section without water proofing layer (Area: 40.400 sq.m. above Rail Level; Total

Excavated area (including Invert) = 67.369sq.m.

6.0 Challenges in front of Design section in finalization of Design and

Drawing of Tunnels:

6.1 Standardization of Tunnel Cross section:

Tunnel cross section can be standardized after taking following factors into

account:

6.1.1 Shape of Tunnel (i.e. Horse Shoe or D Shape).

6.1.2 Cross section is suitable for single Track or Double Track.

6.1.3 Track is Ballasted / BLT.

6.1.4 System of Deep Screening-Mechanical/Manual

6.1.5 Width of Footpath.

6.1.6 Size of Ventilation work and Electrification work.

6.1.7 Use of water proofing membrane or not.

6.1.8 Sectional Speed of Tunnel.

6.1.9 Specific guidelines on spacing of Adits, service tunnels and cross sections.

6.2 Standardization of Primary and Secondary Supporting System:

6.2.1 Primary Support will be standardized after considering the following factors

into account:

After considering different heights of overburden above tunnel crown,

unconfined compressive strength (qu), Geological Strength Index-GSI and other

associates boundary conditions for proposed tunneling. These parameters are to

be given as input to the use of software RocLab (supported by RocScience). The

values have been generally calculated assuming Disturbance factor as D=0 and

output results are Cohesion ‘c’, internal friction angle- ‘(ɸ)’ and Deformed

Elastic Modulus value( Em).

The range of design parameters of the tunnel constructed in Jiribam-Tupul-

Imphal and Bairabi-Sairang Project in N.F.Railway have been compiled with

supporting system and its spacing corresponding to support class-I to Support

Class-VIII and tabulated below. It is observed that, all the tunnels of this area fall

under similar geological region and similar type of Primary support and

secondary support system of corresponding Rock class have been provided.

Range of Design parameter Jiribam – Tupul - Imphal Section: Table No.1

Support Class

Unit weight

Over Burden

C (Mpa) (ɸ) Youngs

Modulus E

Primary Support Report

Shotcrete

th.

Lattice girder & Spacing

Rock bolt & pattern

Deformation +

Construction Tolerance

SC-I 26 18-150m 2.486 50 7050 50mm NA 3m length, if

required 75mm

Sc-II 26 18-150m 1.748 49 4980 100mm NA 4m length,

2nos/m 100mm

Sc-III 26 16-244m 0.56 - 1.85 40-58 2510 - 13269

150mm - 200mm

95/16/25, 1.75m c/c 3m length, 2.8

nos /m 100mm

25/25/20, 2.0m c/c 4m length, 4

nos / m

Sc-IV 26 150-

300m 0.468 - 1.32 38-58

4409 - 13269

200mm

95/16/25, 0.75m c/c - 1.5m c/c 4m length, 5-11

nos / m 100mm - 150mm

95/25/20, 1.5m c/c

Sc-V 24 - 26 44-330m 0.255 - 1.277

33 - 49 1436 - 4300 200mm - 250mm

95/25/20, 1.5m c/c 6m length, 8

nos / m 100mm - 150mm 95/16/25, 0.5 - 1.5m

c/c

4m length, 14-20 nos / m

Sc-VI 24 - 26 16 -

283m 0.08 - 0.969

29 - 46.6

189 - 2153 250mm - 300mm

95/16/25, 0.5 - 1.5m c/c 6m length, 9.6 -

15 nos / m 100mm - 150mm

130/32/25, 1.2m c/c

Sc-VII 24 - 26 16 -

150m 0.07 - 0.217 24 - 42 270 - 420 300mm

130/32/25, 1.0m c/c 6m length, 9 - 13 nos / m

100mm-150mm ISMB-250, 0.5m -

0.9m c/c

Sc-VIII 26 16-244m 0.03 26 123 300mm 130/32/25, 1.0m c/c 6m length, 9 -

14 nos / m 200mm

Range of Design parameter Bairabi – Sairang Section: Table No.2

Support Class

Unit weight

Over Burden

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete thickness


Rock bolt & pattern Deformation + Construction

Tolerance

Sc-II 26 18-

55m 0.87 60 9398 100mm NA 3m length, if required 150mm

Sc-III 26 18-

55m 0.32 47 1496 200mm

95/16/25,2.5m c/c

4m length, 2.8 nos /m 150mm

Sc-IV 26 55 0.19 40 535 200mm

95/16/25, 2.0m c/c 4m length, 5.25 nos / m 150mm

Sc-V 21 - 26 31-

195m 0.09 - 0.195

25.69-43.57

208-844.71

200mm - 300mm

109/16/25, 1.0m c/c

4/6m length, 15 nos / m 150mm

95/16/25, 0.8m c/c

4m length, 12-14 nos / m

Sc-VI 21-25 31-

85m

0.055 -

0.171

15.60-32.54

191.93-448

300mm

109/16/25, 0.75m c/c 4m length, 0.3 m spacing 150mm

Sc-VII 21- 26 18-

50m

0.016 -

0.048

19.3-36.54

53-348 300mm-400mm

95/16/25,0.8m c/c

6m length, 15 nos / m 200mm

ISMB-250, 0.5 c/c (with Steel

lagging) NA 50mm

Form the above tabulated data, it may be interpreted that the primary supporting

system can easily be standardized based on design parameters obtained from the

geological and geo-technical investigation report. The data compiled in Table No.1

and 2 are based on the design parameters, spacing and details of supporting systems

of 27 numbers of tunnels in Jiribam-Imphal Project and 15 numbers of tunnels in

Bairabi-Sairang Project as placed at Annexure-A and Annexure-B respectively.

7.0 Conclusions:

• As Railway gained lot of experience in Tunneling design and execution, the

tunnel cross section and supporting systems may be standardized.

• More data may be collected from all other departments involved in tunnel

construction, for standardization of cross sections and support systems.

• Expert geo consultant is required to be engaged for geological and geo

technical investigation and also supervising/monitoring, suggesting various

measures including supporting systems during execution.

• If any deviation is noticed from the designed data during execution, supporting

system may be redesigned.

• Substantial amount of time and cost can be saved by adopting standard cross

section and supporting systems.

References:

a) Text book on “Railway Tunnels”, published by IRICEN, Pune

b) RDSO Draft Guidelines for Design Construction of Tunnels

c) Tunnel Design Documents of AECOM India Pvt. Ltd for the section Jiribam-Tupul of

Jiribam-Imphal Project.

d) Design Document of GEOCONSULT India Pvt. Ltd for the section of Tupul-Imphal of

Jiribam-Imphal Project and for the Bairabi-Sairang Project.

e) Design Document of BEAVER Infra Consultants India Pvt. Ltd for the Bairabi-Sairang

Project.

f) Indian Standard code for tunneling.

g) Literature on Tunnel design and construction from internet.

Annexure-A:

Tunnel no. 1 to 9 (Tupul - Imphal) 5200 m length

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation + Construction Tolerance

Sc-III 26 16-244 1.6 58 13269

200 (m-25)

95/25/20, 2.5 m

3 m length, 2.8 nos

100mm

SC-IV 26 16-244 0.5 58 13269

200 (m-25)

95/25/20, 2 m

spacing

4 m length, 5 nos

150 mm

SC-V 26 16-244 0.5 49 4300

200 (m-25)

95/25/20, 1.5 m

4 m/6 m length, 8 nos

150 mm

SC-VI 26 16-244 0.08 38 189

300 (m-25)

130/25/32,1.25

m

6 m length, 9.6 nos

150 mm

SC- VII 26 16-244 0.07 40 280

300 (m-25)

130/25/32, 1 m

6 m/ 9 m length, 12 nos

200 mm

SC - VIII 26 16-244 0.03 26 123

300 (m-25)

130/25/32, 1 m

6 m/ 9 m length, 14 nos

200 mm

Tunnel no. 1 (Jiribam - Tupul ) 3019 m length

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-I 26 150 2.486 50 7050

50 mm (

m-25 ) NA 3 m length, 75

SC-II

26 150 1.748 49 4980 100 mm

NA 4 m length, 2.5x2.5, 2nos per m

100

Sc-III

26 150 0.56 40 2510 150

95/16/25, 1.75

m spacing

4 m length, 1.75x1.75, 4 nos per m

125

SC-IV

26 150 0.468 38 1850 200 95/16/25, 1.5 m spacing


150

SC-V

26 150 0.364 33 1240 200 95/16/25, 0.9 m spacing

4 m length, 1.0x1.0, 17.22 per m

150

SC-VI

26 150 0.293 29 770 300 95/16/25, 0.9 m spacing

6 m length, 1.0x1.0, 16.11 per m

150

SC- VII

26 150 0.217 24 420 300

steel rib, 0.9

m spacing

6 m length, 1.0x1.0, 16.11 per m

150


Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-V

24 100 0.46 45 2348 200 95/16/25. 1 m

spacing


SC-VI

24 100 0.32 39.7 850 250 95/16/25. 1 m

spacing


SC- VII (portal)

24 100 0.21 32 270 300 STEEL

RIB, 1 m spacing



Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-IV

24 300 1.32 46 5511 200

95/16/25, 0.75

m spacing


SC-V

24 320 0.898 36.5 2348 200 95/16/25, 0.5 m spacing


SC-VI

24 40 0.19 46.6 850 250 95/16/25, 0.5 m spacing


SC- VII

24 80 0.18 34 270 300

STEEL RIB 250,

0.5 m spacing



Support Unit Over C (ɸ) Youngs Primary Support Report

Class weight Burden Height

(Mpa) Modulus E

shotcrete th.


Rock bolt & pattern

Deformation +


SC-IV 24 300 1.185 41.8 5511 200

95/16/25, 0.75

m

4 m length, 1.5x0.75, 11 nos

100

SC-V 24 300 0.864 37 2348 200

95/16/25,0.75

m

4 m length, 1.5x0.75, 14 nos

100

SC-VI 24 70 0.257 42.5 850 250

95/16/25, 0.75

m

6 m length, 1.0x0.75, 14 nos

100

SC- VII 24 40 0.116 39 270 300

STEEL RIB 250,

0.5 m

6 m length, 1.0x0.5, 10 nos

100

Tunnel no. 6A (Jiribam - Tupul ) 859 m length

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-IV

24 180 0.92 45.6 4409 200 95/16/25, 105

m

4 m length, 1.5x1.5, 6.66 nos

100

SC-V 24 100 0.46 45 1878 250

95/16/25, 0.9 m

4 m length, 1.0x1.0, 16.66

100

SC-VI 24 60 0.23 43.6 680 300

95/16/25, 0.9 m

6 m length, 1.0x1.0, 16.66

100

SC- VII (portal)

24 40 0.14 43.8 240 300

STEEL RIB

250,0.9 m


100


Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-IV

24 250 1.077 43 3674 200 95/16/25, 105

m

4 m length, 1.5x1.5, 6.66 nos

100

SC-V 24 230 0.74 39 1565 250

95/16/25, 0.9 m

4 m length, 1.0x1.0, 16.66

100

SC-VI 24 100 0.32 40 680 300

95/16/25, 0.9 m

6 m length, 1.0x1.0,

100

16.66

SC- VII (portal)

24 80 0.18 34 215 300 STEEL RIB 250,0.9m

6 m length, 1.0x1.0, 10 nos.

100


Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-V 24 330 1.277 44.23 3801 200

95/16/25,0 .75

m


SC-VI 24 283 0.969 42 2153 250

95/16/25, 0.6 m



Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-A 25 112 0.35 38.56 850 200

95/16/25


SC-B (PORTAL)

25 30 0.1 40.98 269 300 STEEL

RIB 250


spacing not seen in

design report


Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III 26 1.85 47.8 12310

SC-IV(a) 26 1.147 43 5756 200

95/16/25

4 m length, 1.5x1.5

100

SC-IV(b) 26 1.147 43 5756 200

95/16/25

4 m length, 1.5x1.5

100

SC-V (a) 26 0.604 41.7 2350

SC-V (b) 26 0.51 39 1436

SC-VI 26 0.411 36.5 850

SC- VII ( C ) portal

26 0.102 40.7 270

Tunnel no. 25 (Jiribam - Tupul )

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete

thickness.


Rock bolt & pattern

Deformation +


Sc-III 26 1.9 47.16 12310 150

95/16/25

4 m length, 1.75x1.75

100

SC-IV(a) 26 0.53 56.5 5756

SC-IV(b) 26 0.53 56.5 5756

SC-V (a)

26 0.85 37.2 2340 200 95/16/25, 0.9 m

4 m length, 1.0x1.0, 15.55 nos

SC-V (b)

26 0.73 34.5 1436 250 95/16/25, 0.9 m

4 m length, 1.0x1.0, 15.55 nos

SC-VI 26 0.43 36 850 300

95/16/25, 0.9 m



26 0.102 40.7 270 300 steel

ribs 250, 0.9 m

6m length, 1.0x1.0, 11.11 nos


Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III 26 1.85 47.8 12310

SC-IV(a) & IV(b)

26 0.973 45.4 5756

SC-V (a) 26 0.81 37.8 2340

SC-V (b) 26 0.695 35 1440

SC-VI 26 0.41 36.5 850


26 0.102 40.7 270


Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III 26 1.5 52 12310

SC-IV(a) & IV(b)

26 0.824 48 5756

SC-V (a) 26 0.545 43.14 2348

SC-V (b) 26 0.46 40.4 1436

SC-VI 26 0.28 41.3 850


26 0.102 40.7 270

Tunnel no. 17 to T23A (Jiribam - Tupul ) 6961 m length

Tunnel no. 17

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III

26 185 1.673 49.64 12320 150 95/16/25, 1.75

m

4 m length, 1.75x1.75, 3.42 NOS

SC-IV(a)

26 185 0.986 45.17 5757 200 95/16/25, 1.5 m

4 m length, 1.5x1.5, 6.66 NOS

SC-IV(b)

26 185 0.986 45.17 5757 200 95/16/25, 1.5 m

4 m length, 1.5x1.5, 6.66 NOS

SC-V (a)

26 198 0.7 39.72 2348 200 95/16/25, 0.9 m

4 m length, 1.0x1.0, 15.55 NOS

SC-V (b)

26 198 0.597 36.99 1437 250 95/16/25,0.9 m

4 m length, 1.0x1.0, 15.55 NOS

SC-VI

26 220 0.54 33.05 850 300 95/16/25,0.9 m

6 m length, 1.0x1.0, 15.55 NOS


26 25 0.09 42.05 270

Tunnel no. 18

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III 26 127 1.508 51.91 12320

SC-IV(a) & IV(b)

26 127 0.83 47.86 5757

SC-V (a) 26 118 0.53 43.58 2348

SC-V (b) 26 118 0.442 40.88 1437

SC-VI 26 100 0.334 39.13 850


26 33 0.108 39.98 270

300

Steel rib 250, 0.9 m

6 m length, 1.0x1.0, 15.55 NOS

Tunnel no. 19

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation + Construction

Tolerance

Sc-III 26 177 1.65 49.92 12320

SC-IV(a) & IV(b)

26 177 0.966 45.5 5757

SC-V (a) 26 177 0.664 40.47 2348

SC-V (b) 26 177 0.563 37.74 1437

SC-VI 26 177 0.475 34.72 850


26 25 0.09 42.05 270

Tunnel no. 19 A

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III 26 95 1.415 53.5 12320

SC-IV(a) & IV(b)

26 95 0.737 49.83 5757

SC-V (a) 26 44 0.322 50.65 2348

SC-V (b) 26 44 0.255 48.23 1437

SC-VI 26 95 0.324 39.53 850


26 32 0.106 40.21 270

Tunnel no. 20

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


Sc-III 26 95 1.415 53.5 12320

SC-IV(a) & IV(b)

26 95 0.737 49.83 5757

SC-V (a) 26 95 0.469 45.2 2348

SC-V (b) 26 95 0.39 42.55 1437

SC-VI 26 72 0.274 41.65 850


26 30 0.102 40.69 270

Tunnel no. 27 A (Jiribam - Tupul ) 72 m length Support Unit Over C (ɸ) Youngs Primary Support Report

Class weight Burden Height

(Mpa) Modulus E

shotcrete th.


Rock bolt & pattern

Deformation +


SC-VI

24 27 9.3 0.763 453 300 95/16/25,0 .9 m

6 m length, 1.0x1.0, 17.77 nos

100 MM

SC-VII( PORTAL)

24 11.5 9.3 0.534 152 300 STEEL

RIB 250, 0.9 M


100 MM

Tunnel no. 21 B(Jiribam - Tupul ) 236 m length

Support Class

Unit weight

Over Burden Height

C (Mpa)

(ɸ) Youngs

Modulus E


shotcrete th.


Rock bolt & pattern

Deformation +


SC-VI

24 50.5 9.3 0.763 453 300 95/16/25,0 .9 m

6 m length, 1.0x1.0, 17.77 nos

100 MM

SC-VII( PORTAL)

24 7.5 13.7 0.787 172 300 STEEL

RIB 250, 0.9 M


100 MM

Annexure-B:

Tunnel no. 10 (Bhairabi-Sairang)

Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-V

25 85 0.195 31.23 767.76 300 (m-

25) 109/16/25,

1.0m

4 m length, spacing 12-14 per m,

150 mm

SC-VI 25 85 0.171 30.01 447.86

300 (m-25)

109/16/25, 0.75m

4 m length, spacing 0.3 m,

150 mm

SC- VII (Portal)

25 18 0.048 36.54 309.94 400 (m-

25) ISMB 250,

0.5 M NA 50 mm

Tunnel no.9 (Bhairabi-Sairang)

Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-V

25 57 0.108 29.31 207.93 300 (m-

25) 109/16/25,

1.0m


150 mm

SC-VI 25 57 0.084 26.02 191.93

300 (m-25)

109/16/25, 0.75m


150 mm

SC- VII (Portal)

25 18 0.031 530.27 160.62 400 (m-

25) ISMB 250,

0.5 M NA 50 mm


Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-V

24 31 0.149 43.57 844.71 300 (m-

25) 109/16/25,

1.0m


150 mm

SC-VI 25 31 0.065 32.54 218

300 (m-25)

109/16/25, 0.75m


150 mm

SC- VII (Portal)

25 18 0.047 36.3 218 400 (m-

25) ISMB 250,

0.5 M NA 50 mm

Tunnel no.22Bhairabi-Sairang)

Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete thickness


Rock bolt & pattern


SC- VII (Portal)

24 50 0.063 26.46 343.62 400 (m-

25) ISMB 250,

0.5 M NA 50 mm

Tunnel no.17 ,18, 20, 21, 23 (Bhairabi-Sairang)

Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-V

21 195 0.09 30.76 844.71 300 (m-

25) 109/16/25,

1.0m


150 mm

SC-VI 21 45 0.055 20.55 218

300 (m-25)

109/16/25, 0.75m


150 mm

SC- VII (Portal)

21 18 0.016 20.31 218 400 (m-

25) ISMB 250,

0.5 M NA 50 mm

Tunnel no.6 ,12, 14 (Bhairabi-Sairang)

Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-V

25 75 0.135 25.69 850 300 (m-

25) 109/16/25,

1.0m


150 mm

SC-VI 25 75 0.084 15.6 408

300 (m-25)

109/16/25, 0.75m


150 mm

SC- VII (Portal)

25 18 0.018 19.3 185 400 (m-

25) ISMB 250,

0.5 M NA 50 mm


Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-ADECO A

26 34 0.02 22 53 200 90/20/25,

1.0 M NA

SC-ADECO B

26 34 0.02 22 53 300 130/25/32,

1.0 M Fibre Glass Bolts,

Tunnel no.2,4 (Bhairabi-Sairang)

Support Class

Unit weight

Over Burden Height

C (Mpa) (ɸ)

Youngs Modulus

E


shotcrete th.


Rock bolt & pattern


SC-II 26 55 0.87 60 9396 100

NA 3 m length,AS REQUIRED 150mm

SC-III 26 55 0.32 47 1496 200

95/16/25, 2.5 m

4 m length, 2.5mX2.5m, 2.8 nos per m 150mm

SC-IV 26 55 0.19 40 535 200

95/16/25, 2 m

4 m length, 2mx1.5m, 5.25 nos per m 150mm

SC-V 26

55 0.135 25.69 850 200 (m-

25) 95/16/25 ,

0.8 m

4/6 m length,0.8mx1m , 15 nos per m

150 mm

SC- VII 26

20 0.02 22 53 300 95/16/25,

0.8 m

6 m length, 0.8 mx1.0 m, 15 nos per m

200mm