CH-RF-IN-Gabion and Netting applications for Konkan Railway Route

CASE HISTORY
Rev: 00, Issue Data 25.10.07
GABION& NETTING APPLICATIONS
KONKAN RAILWAY (KRCL) ROUTE,INDIA
ENVIRONMENTAL/ SLOPE PROTECTION/BALLAST RETENTION
Product: Gabions,Baby Gabions & Rockfall Netting
Problem: Konkan Railway Project can be considered as one of
the most prestigeous projects in the Construction Industry of
India.The project was launched in 1989 and the track became
operational in the year 1998.The 760 km line passes through
complex terrains.In many of the stretches, the available space
was restricted and the side slopes were very steep.This
formidable terrain and the short construction period
necessitated the use of several technological innovations.
The construction and widening of the track called for large
quantities of cutting in rocks of lateritic and basaltic origin.The
exposed lateritic terrains were subjected to heavy rainfall and in
the presence of water, the laterite loses all of its
cohesiveness,strength and become very vulnerable to cause
heavy slides and slips.This problem necessitated the provision
of several landslide mitigation techniques like construction of
proper retaining walls and rockfall prevention measures.
The ballast which is laid below the tracks primarily serves the
purpose of load dispersion apart from giving added
resiliance.Conventionally, a ballast layer of depth 250 mm is
adopted below the sleepers with a depth of 500mm on the
sides,sloping outwards.This requires a greater utilisation of
space on the sides, with sufficient width for
embankment.Further over a period of time,due to the repeated
use of track,the ballast has a tendency to roll out of tracks.The
Fig 1.A typical KRCL stretch with narrow tracks & steep side slope
Solution
Maccaferri Gabion walls with stepped rear face were adopted
in many vulnerable stretches of hill cuttings of Konkan Railway.
Backfill soil was carefully selected ensuring the omission of
clayey soil. Additional arrangements included provision of
transverse drainage system, comprising of 2.9mm dia heavy
duty PVC pipes per metre laid at a slope of about 1:20.to
carry water away from the foundation. The foundation comprised basically of lateritic soil. Owing to the relatively high
level of water table, the foundation depth was restricted to a
minimum of 0.5m. At places where the foundation comprises of
very fine clayey soil, Terram 1000 Geotextile was placed at the
bottom of the Gabion Wall in addition to the backside in order
to prevent the ingress of fines. Gabion walls were selected
due to its flexibility, speed in construction and fine draining
nature.
Client name:
KONKAN RAILWAY CORPORATION LIMITED
Main contractor name:
A NUMBER OF SMALL CONTRACTORS
Consultant:
ENGINEERING DIVISION OF KRCL,MUMBAI IIT,MACCAFERRI
Product used:
50,000 CUM OF GABIONS,10000 SQM OF NETTING
Construction info
Construction Start:
Construction end:
Fig 2 .Gabions for landslide mitigation constructed in 2001
FEBRUARY 2000
MARCH 2005
Fig 3,4.Gabions for Platform construction at Ratnagiri & Kudal Railway Stations respectively
Along the Konkan Railway Route, instead of using the conventional methods, Gabion boxes were used for
the construction of about 12 railway platforms. This innovative step resulted in easy and speedy construction of railway platforms. After successful installation at one platform, they found it a very cost effective solution. The cost was reduced to around 50% as compared to traditional construction methods.
Fig 5.Gabion Structure for abutment protection during construction
Project section drawing
Fig 6 Structure completed in 2004 for abutment protection
TYPICAL SECTION OF RAILWAY TRACK WITH BABYGABION BALLAST RETAINERS
Fig 7. Baby Gabions for ballast retention
.
For the retention of ballast and reduce periodical maintenance, an entire new size of Gabions were adopted in
Konkan Railway tracks. These Gabions are referred as baby Gabions and are of much smaller size, say
4mx.3mx.3m and 2mx0.5mx0.5m with a mesh opening size of 60 mmx80 mm, and 2.2mm wire diameter. Apart
from less maintenance and retention of ballast, Baby Gabions, it was possible to reduce the width of embankment
and thus to reduce the quantity of earthwork to a great extent by the adoption of Baby Gabions.
Fig 8. Bottom anchoring of DT Mesh
Fig 9 Slope after vegetation has grown
To prevent rock fall from the side hill slopes, double twist
hexagonal PVC Coated Maccaferii netting of type 10x12
was laid along the slope and then anchored into the
trench using suitable anchoring techniques. Double twist
Mesh was selected over chain link mesh as it is not prone
to unraveling. Their high tensile strength, punching resistance and low installation costs also helped the adoption
of this system.
Fig 9 Rockfall Protection Netting using Maccaferri’s DT
Project section
Maccaferri Environmental Solutions Pvt. Ltd.
1003,10th Floor,Casablanca,Plot No.45,Sector-11,CBD Belapur,Navi Mumbai-400614
Tel. 91-22– 27580475/27565451/ 27565906/27580931/ 27580932 - Fax (022) 27580488
E-mail: [email protected], [email protected] - Web site: www.maccaferri.com