The said paper by Rajesh Prasad Executive Director RVNL has been published in IPWE international seminar held on 23/24-02-2018. The power point presentation nicely explains about how the technical challenges and administrative challenges addressed in completion of the tunnel while constructing a tunnel by the side of a railway tunnel with train operation in place and the entire area is affected by LWE activities.

1. Execution of 680 m long tunnel ensuring safety of the adjoining
rail tunnel with controlled blasting and monitoring in maoist
affected zone of HDN route of S.E. Railway
By
Rajesh Prasad
Executive Director
Rail Vikas Nigam Limited

2.  680 m long tunnel execution.
 Monitoring of Vibration and Peak particle velocity in the
adjoining tunnel.
 Execution in LWE area.
GOELKERA – MONOHARPUR 3RD LINE
Length 27.5 Km
Phase-I (Posoita to Manoharpur) 11.6 KM
Phase –I Commissioned on 04.05.2016
Phase-II (Goelkera to Posoita) 15.9 KM
SCOPE
 RVNL Kolkata PIU is Implementing Agency
 M/s Unity-Triveni-BCPL (JV) are main Contractor.
 Central Institute of Mining & Fuel Research (CIMFR)
Roorkee - DDC (Cost Rs. 80 Lakh)
 M/s SNC-Lavalin - PMC. (Cost Rs. 2.7 Crores)
AGENCIES INVOLVED
TECHNICAL CHALLENGE
 3rd Line tunnel very close to the existing tunnel (c/c 31 m)
ADMINISTRATIVE CHALLENGE
 LWE affected area.

3. FEATURES IN TUNNEL EXECUTION
 Curves in Tunnel alignment :
305m , straight with two curves of 3° in approach.
Gradient - 1 in 100
 Size and Shape of Tunnel:
 Modified Horse Shoe shaped
 Excavation Height – 8.041m. & Width – 7.365m.
 Excavating by heading and benching method
 Controlled blasting technique
 Ventilation shaft
 Steel rib support in portal and weak rock area
 Steel fibre reinforced shotcrete (SFRS)
 Rock bolt
 Concrete Backfilling
 LED lighting
 Monitoring system (to ensure safety of the adjoining tunnel) for
the first time in IR

4. General complete cycle of tunnel excavation by drill and blast
Drilling
Survey
Bolt
Scale Dislodged
Ventilate
Blasting
Loading

5. ROCK BLASTING
Desirable Effects Unwanted Effects
• Breaking the rock mass
into desired shapes &
sizes.
• Displacing the broken
rock
• High Production/Pull
• Ground Vibration
• Air-blast
• Flyrock
• Over-Breakage
• Back break
• Damage to Rock Mass
• Cost escalation
• Increased cycle time

6. Rock strata encountered during execution tunnel
PHYLLITE ROCK
(Crack at 71º angle)
QUARTZITE ROCK
CARBONACEOUS SHALE

7. Tunnel excavation by Blasting
• The blast designs with MCD (Maximum
Charged density) of 14.0kg.
• Controlled blasting has been done
under guidance and direction of DDC i.e
CIMFR.
• Heading & benching method due to poor rock condition where stand up
time is not very high.
• Controlled blasting technique for the excavation of tunnel, trolley refuge,
ventilation shaft.

8. • Tunnel heading portion is approx. 26 Sq.m.
• Heading excavation is carried out by drilling (38 mm hole dia) with loading
of emulsion explosive of dia 32mm and blasting with a maximum pull 1.8m.
• Forepoles have been provided at immediate roof with the support of Steel
Ribs.
• Water seepage control - necessary arrangement of pumping of water.
• Depending upon Rock mass stand-up time, immediate support of 100 mm
thick reinforced shotcrete (SFRS) is being done by wet shotcrete machine.
• Approx. 12 nos to 14 nos of Rock bolting (3 m length) @ 1.5m c / c in
staggered way are provided.
• After rock bolts erection, steel ribs of ISMB 200 are placed @ 0.6m c / c
with 3.15 mm thick steel lagging before concrete back filling .
• Cement grouting is done between back fill concrete and rock surface area .
• Perforated PVC pipes are provided for weep holes at a spacing of 3.0 m
interval in staggered way to take care of surface seepage .
Heading Excavation

9. • Area of tunnel benching portion is approx. 25 Sq.m.
• Benching excavation is done when the heading face of tunnel is about
14 m to 15 m away.
• Excavation of benching part is also carried out through drilling and
blasting method with a maximum pull of 1.8 m by using controlled
blasting as per blasting design.
• After the benching, the side wall supports are fixed on wall beam of
ISMB 200.
• 100mm thickness of SFRS(Steel fibre reinforce shotcrete) is sprayed
before erecting Rock bolts.
• Minimum 4 to 6 nos. of rock bolts are provided below spring level
(benching portion) of the spacing between rock surface and steel ribs
and back filled with M20 Grade concrete by using concrete pump.
• Cement grouting is done before placing perforated PVC weep holes.
Benching

10. Explosive:
The latest generation emulsion explosive (power gel of ORICA make
having 25 mm dia ,200 mm long and 125 gm by weight ) with 80-90%
strength for blasting is used . The explosive is adequately sensitive,
powerful and safe. For initiation of non-electric detonators (also termed
as shock tube initiation system) of long delay is used. Afterwards Electric
detonators with long delay series (excel series) is being used in
underground tunnel blasting. 1.8 m deep blast hole is generally filled with
60% of emulsion explosive and remaining 40% length is filled by mud
stick.
LOADING OF EXPLOSIVE

11. Electronic Detonator
The sequence of delay blasting by choosing 1 to 12 delay series of LDD
(Long Delayed Detonator). The placement of LDD’s in heading is shown
below. By this, blastings were done in sequences and during each
blasting amplitude of shock waves was reduced to keep it within
permissible limit for safety of nearby existing tunnel.
Cross section of ED

12. Fixing of Electronic Detonator (LDD) for Blasting

13. VENTILATION SHAFT
A ventilation shaft (2.0 m dia) circular in shape at the
centre of the tunnel, i.e. at ch. 6300m has been provided.
The shaft is around 35m deep from exposed surface of
mountain to feed fresh air inside tunnel as well as natural
lighting to some extent.

14. STEEL RIBS
Specification of Steel Rib Support at Portal Area :
Type of Steel Rib : ISHB 200
Weight per meter : 0.366 kN
Cross-Section Area : 47.54 cm2
Spacing of rib : 100 cm at both the ends of tunnel
Plain Shotcrete : M20
Steel rib supports have generally been used for the portal zone
and inside the tunnel due to poor rock condition, except 160 m in
patches where the rock support has been given by shotcreting
only. ISHM 200 steel rib supports has been used. At back portion
of steel rib & between the rock surface, the gap has been filled up
by normal concrete so that full arch action could be generated for
stability of tunnel.

15. STEEL RIBS

16. Specification of Shotcrete in the Tunnel
Steel Fibre Reinforced Shortcrete (SFRS) of standard
mix was used with 28 days UCS (Uniaxial Crushing
Strength) of 50 Mpa and good bonding with the rock
surface.

17. FIBRE REINFORCED SHOTCRETE

18. SLOPE PROTECTION BY
FIXING WIREMESH
SLOPE PROTECTION BY
FIXING ROCK BOLT
SHOTCRETE AT APPROACHES

19. Rock Bolt
Specification of Rock Bolt in the Tunnel :
Length : 3.0 m
Diameter : 25mm tor steel
Base Plate Size : 15 cm x 15 cm
Thickness of Base Plate : 12mm
Pullout Capacity of bolt : More than or equal to 15 tones fully grouted
Spacing : Staggered systematic 1.5m centre to centre

20. Monitoring System
• Controlled blasting under
guidance of DDC.
• Monitoring system for
measuring vibration in the
existing tunnel during blasting
of 3rd line.
• Seismograph equipment was
installed in near by existing
tunnel wall during every
blasting to record the blasting
amplitude and frequency of
shock wave.

21. Inducespolarityofsignal
Longitudinal geophone (L)
Vertical geophone (V)
Transverse geophone (T)
The arrows indicate positive and negative ground motion represented by waveforms
TIME
+
+
+
-
-
-
+
T
+ V
+
L
-
-
-
Event
Standard Transducer
Ground Vibrations
V= Vertical
T= Transverse
L=Longitudinal
Microphone
Air Pressure
Monitoring Device
Limiting/Safe Value
PPV= 10mm/sec.
Noise = 146 dB

23. The summary of blast vibration
and Fast Fourier Transform
Analysis (FFT)
PPV = 4.572 mm/s< 10mm/sec.
Noise = 106.0 dB < 146 dB

24. Administrative Challenge
STATUS OF LAW AND ORDER CONDITION AS REFLECTION IN NEWS
PAPER (Dec. 2017)
पश्चिम स िंहभूम में िाईबा ा के पोड़ाहाट जिंगल के ोनुवा
थाना के कु दाबुरु गािंव के पा नक् सलयों ने िार ट्रैक्टर और
एक जे ीबी मशीन में आग लगा दी. आज ोमवार दोपहर
एक बजे के करीब नक् सलयों ने के नाल के ननमााण में ठेका
किं पनी के काम लगे इन भारी वाहनों व मशीन में आग लगाई.
घटना की जानकारी समलने के बाद िाईबा ा ए पी अनीश
गुप्ता और ऑपरेशन असभयान ए पी मनीष रमन िाईबा ा
े घटना स्थल पर पहुिंिे. दोनों पुसल अधिकाररयों ने घटना
स्थल पर पहुिंि जािंि की और पा के लोगों े पूछताछ की.
उन्हें घटना के बारे में कु छ महत्वपूणा जानकारी समली.
िाईबा ा ए पी ने अनीश गुप्ता ने बताया कक भाकपा
माओवादी के कमािंडर जीवन किं डुलना के दस्ते ने लेवी के सलए
घटना को अिंजाम ददया है.घटना के बारे में बताया गया कक
के नाल का ननमााण काया स्थल पर दोपहर एक बजे अिानक
बड़ी िंख्या में हधथयारों े लै नक् ली पिंहुिे और वाहनों में
आग लगा दी.
Law and Order is still an issue.

25. Execution in LWE area
• LWE – notified by Government of Jharkhand.
• Past History – armed miscreants attacked tunnel
camp. 19 nos. earth moving equipments,
excavators, compactors etc. were burnt at the
tunnel site.
• It has happened twice in the section.
• No Storage of explosive was permitted earlier.
• Subsequently after meeting of CRB with Hon’ble
CM Jharkhand on 06.12.2017, additional forces
have been deployed and night working has also
been permitted.

26. Work is being executed under 100% security cover of SAP posted
by State Government of Jharkhand

27. MOVEMENT AND STORAGE OF EXPLOSIVE

29. • The technical challenge of ensuring safety of the existing tunnel has
been met by using Vibration Monitoring System under the supervision
of CSIR – CIMFR.
• Technique is basically to have the delay introduced in sequence of
blasting so that peak particle velocity of shock waves generated after
blasting should not exceed the permissible limit in the existing nearby
tunnel with train operation in place.
• The administrative challenge of execution in maoist area has been
resolved by having regular meetings with the senior officials of
Government of Jharkhand and under the 100% protection of the force.
• The tunnel work is likely to be completed by March, 2018 which was
the most critical part of the project and the section is being
commissioned in coming few months to benefit in de-congestion of
the Howrah – Mumbai HDN route.
• For the first time in Indian Railways, this monitoring system has been
used to ensure safety of the existing tunnel while executing a new
tunnel for double line or third line project.
CONCLUSION

30. Team Work
TEAMWORK divides the TASK
and multiplies the SUCCESS

31. THANK YOU
31