CASE HISTORY Rev: 00, Issue Data 25.10.07

ENVIRONMENTAL/ SLOPE PROTECTION/BALLAST RETENTION Product: Gabions,Baby Gabions & Rockfall Netting

GABION& NETTING APPLICATIONS KONKAN RAILWAY (KRCL) ROUTE,INDIA

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

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 com-

prised 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

50,000 CUM OF GABIONS,10000 SQM OF NETTING

Construction info

Consultant:

Product used:

Construction Start:

ENGINEERING DIVISION OF KRCL,MUMBAI IIT,MACCAFERRI

FEBRUARY 2000

Fig 2 .Gabions for landslide mitigation constructed in 2001

MARCH 2005 Construction end:

Fig 1.A typical KRCL stretch with narrow tracks & steep side slope

Project section drawing

Fig 3,4.Gabions for Platform construction at Ratnagiri & Kudal Railway Stations respectively

Fig 5.Gabion Structure for abutment protection during con-

struction Fig 6 Structure completed in 2004 for abutment protection

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 construc-tion of railway platforms. After successful installation at one platform, they found it a very cost effective solu-tion. The cost was reduced to around 50% as compared to traditional construction methods.

.

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.

TYPICAL SECTION OF RAILWAY TRACK WITH BABYGA-

BION BALLAST RETAINERS

Fig 7. Baby Gabions for ballast retention

Fig 8. Bottom anchoring of DT Mesh

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: marketing@maccaferri.co.in, technical@maccaferri.co.in - Web site: www.maccaferri.com

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 resis-

tance and low installation costs also helped the adoption

of this system.

Fig 9 Slope after vegetation has grown

Fig 9 Rockfall Protection Netting using Maccaferri’s DT