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GEO TEXTILE: PERSPECTIVE FROM THE RAILWAY SECTOR
A K Shrivastava. Executive Director Railway BoardRajesh Agarwal Geo-technical Engineering Directorate RDSO
Presentation on 19.11.2010 at New Delhi
Introduction Geo textile / Geo synthetics a Polymer
based product of Polypropylene, Polyester, PVC, Polyamide, Polyethylene
Various types of Geo syntheticsGeo textilesGeo gridsGeo netsGeo cellGeo membranesGeo compositesPrefabricated Vertical Drains (Band
Drains)
Functions of Geosynthetics Geo-synthetics improve mechanical
and hydraulic behaviour of formations Basic functions of geo-synthetics: Separation Filtration Drainage Reinforcement Barrier Basal Layer
Railway Track is porous – RoadVarying formation soil across country v/s
need of uniform track formation response.Cumbersome and costly to transport
specified soil material at all places. Specifications of formation, Ballast &
Blanket materials are different from highwayGeo-synthetic can be an economical aid in
improving train load carrying capability. Geo-synthetic works as separation barrier,
prevent rutting, ballast puncturing, improve soil bearing capacity, distribute load better
RAILWAY TRACK FORMATION
Steep Slope Construction ( Non Railway Loading)
Embankment Slip repairs
Construction of high banks on soft soil
Erosion control of slope
Protection against rock falls
Application In Railway (General)
Track Bed Design
Reinforced Earth Embankment
Formation Rehabilitation
Application In Railway (Specific to railway loading)
Application In RailwayNew Constructions
• ‘Dedicated Freight Corridors• ‘High Speed Corridors.’
• Heavy axle loads / high speed railway track require stable track formations.
• Geo-synthetics can help to avoid repeated maintenance and provide stable railway
formation• Need to be designed as per site boundary
condition
Application In Railway Open-line / Revenue line)
• IR is upgrading infrastructure to meet future demand of higher axle load traffic.
• About 700 km track is on weak formation• cause of ballast penetration, higher fuel consumption, passenger discomfort, extra
maintenance cost to track and rolling stock, • Rehabilitation / strengthening of such track
can help to eliminate speed restrictions
Use of Synthetic Use of Synthetic Geogrids for Erosion Geogrids for Erosion
Control of Natural Control of Natural Existing SlopesExisting Slopes
Construction of RE EmbankmentConstruction of RE Embankment
11
Typical Cross Section of Typical Cross Section of Embankment with Prefabricated Embankment with Prefabricated
Vertical Band DrainsVertical Band Drains
Sand Blanket
Initial Embankment
Soft Clay
Layer
Band drains
Firm Soil
12
Band drains installed above Band drains installed above initial embankmentinitial embankment
USES OF GEO-GRID
GEOSYNTHETICS APPLICATION IN RAILWAY FORMATION
GEOSYNTHETICS APPLICATION IN RAILWAY FORMATION
PROJECT : JAMMU-UDHAMPUR RAIL LINK.
At km 54/043 near bridge no 162 in Udhampur yard, embankment constructed with 35 m height .
• Due to space constraint and close proximity of irrigation canal and Tawi river at the bottom of hill, not possible to provide designed slope of 2.5H : 1V.
• RE slope was constructed with Uniaxial Geogrid of slope of 1.5 H : 1V.
Railway Loading are different: Cyclic Vibrations Effects Traction (mainly Electrical) Seismic Effects when train is running Impact loading Maintenance of track should not be
infringed by geo-synthetics Rehabilitation methods after completion
life cycle of geo-synthetics
Why do the Industry should develop customized geo synthetics for railway
track formation application?
FORMATION REHABILITATION Work is to be done on running traffic condition
Methods available for formation rehabilitation such as
With aluminium alloy girder, Track dismantling method, With manually operated portals, With c. c. crib & rail clusters (SE Railway Method), With rail clusters (Eastern Railway Method), Lifting of track with deep screening, Fully mechanized methods.
Above methods are tedious in operation, alternative method need to be explored.
Railway is interested in develop cost effective easy to lay geo-synthetics.
HISTORY OF GEO-SYNTHETICS TRIED IN IR
• First time Geo-textiles were tried in Sothern Railway (Madras - Gudur section, RDSO’s report no.C-261, July, 83) for prevention
of Mud pumping under ballast.
•Geotextile were tried over 12 no. of different sites all over Indian Railways in 80’s and a compilation report ‘State of the Art – Use of
Geotextile in Railways, Nov. 89 was prepared by RDSO giving recommended specification of geo-textile for track formation.
• Trials of geo-jute along with blanket layer have been done in Eastern Railway but not added strength to blanket layer. Geo-jute
can improve only drainage properties.
•Geo-grid was tried in Cuttack – Paradeep section for track construction over soft soil and design of geo-grid reinforced
embankment, retaining wall and on bridge approach in Jammu-Udhampur section, N .Rly (RDSO Report no. GE-13 &14,
May.1997.
Geo-grid in IRGeo-grid in IR Biaxial geogrid has been used in South Central Biaxial geogrid has been used in South Central
Railway, Northern Railway (Polypropylene – Railway, Northern Railway (Polypropylene – strength 30 kN/m with aperture size of 61mm x strength 30 kN/m with aperture size of 61mm x 61mm) for formation rehabilitation. 61mm) for formation rehabilitation.
Field observations on SCR & NR indicate Field observations on SCR & NR indicate improvement in overall track performance after improvement in overall track performance after the application of geogrid. the application of geogrid.
Geo-grid + Geotextile on IRGeo-grid + Geotextile on IR NF Railway has tried use of Geo-grid (Polyester based NF Railway has tried use of Geo-grid (Polyester based
– knitted & coated with strength of 40 kN/m & aperture – knitted & coated with strength of 40 kN/m & aperture size of 25mmx25mm) in combination of geo-textile size of 25mmx25mm) in combination of geo-textile and sand layer for formation rehabilitation. The and sand layer for formation rehabilitation. The performance report of the trial section is satisfactory. performance report of the trial section is satisfactory.
For low density routes, geotextile along with sand For low density routes, geotextile along with sand layer and brick soling has been used in Sitamarhi – layer and brick soling has been used in Sitamarhi – Darbangha project, ECR.Darbangha project, ECR.
CURRENT PROCETS WITH GEO- SYNTHETICS
Issues involved
Aperture size of Bi-axial geogrid Junction strength Material type
WORLD RAILWAY PRACTICE ON USE OF GEO-SYNTHETICS Geo-synthetics being used on many world railways.
American Railways Use of geo-synthetics is on experimental basis and
specific to the nature of problem. Specification of geo-synthetics is in draft stage.
Australian Railways specify use of geotextile and Geogrid for
reconditioning/ rehabilitation of existing track (Draft guideline).
UIC – European Railways UIC consist of different railways. Their loading conditions are different for different railways and
based on the soil type. It is recommendatory in nature
CURRENT PROCETS of GEO- SYNTHETICS
Railway Budget Speech (2010-11) lay emphasis on use of Jute-geo-textile is to enhanced for formation rehabilitation under track.(Rehabilitation)
Project with IIT/Kharagpur for improving tensile strength of jute-geotextile with synthetic polymers
Project with IIT/Delhi to study behavior of different Geo-synthetics to be used in Railway Formations–validation through Lab model, FEM model & site measurements
Recent Documentation on Geo-Recent Documentation on Geo-synthetics in IRsynthetics in IR
Draft ‘Guidelines for use of Geo-synthetics Draft ‘Guidelines for use of Geo-synthetics on Indian Railways’ has been prepared by on Indian Railways’ has been prepared by RDSO provisional specifications of various RDSO provisional specifications of various geosynthetics items based on relevant geosynthetics items based on relevant literature survey literature survey
Extended field trials on geogrid are being Extended field trials on geogrid are being done on IR to validate & assess the done on IR to validate & assess the specifications of geogrid. specifications of geogrid.
FOR INDUSTRY Geo-synthetics can find its use in railway application
for track bed stabilization,
track drainage, erosion control, interface protection, construction over soft soil,
steep slope construction, mud pumping, etc. There is need to develop cost effective easy to lay geo-synthetics for application in construction of new formations & rehabilitation of existing formations for running of heavy axle loads and high speed trains.
IR look forward active participation of industry in this sector.
THANKSTHANKS