GEO TEXTILE: PERSPECTIVE FROM THE RAILWAY SECTOR A K Shrivastava. Executive Director Railway Board Rajesh Agarwal Geo-technical Engineering Directorate RDSO Presentation on at New Delhi

Introduction Geo textile / Geo synthetics a Polymer based product of Polypropylene, Polyester, PVC, Polyamide, Polyethylene Various types of Geo synthetics  Geo textiles  Geo grids  Geo nets  Geo cell  Geo membranes  Geo composites  Prefabricated 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 – Road  Varying 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 highway  Geo-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 Railway New 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 Geogrids for Erosion Control of Natural Existing Slopes

Construction of RE Embankment

11 Typical Cross Section of Embankment with Prefabricated Vertical Band Drains Sand Blanket Initial Embankment Soft Clay Layer Band drains Firm Soil

12 Band drains installed above initial embankment

USES OF GEO-GRID 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 IR Biaxial geogrid has been used in South Central Railway, Northern Railway (Polypropylene – strength 30 kN/m with aperture size of 61mm x 61mm) for formation rehabilitation. Biaxial geogrid has been used in South Central Railway, Northern Railway (Polypropylene – strength 30 kN/m with aperture size of 61mm x 61mm) for formation rehabilitation. Field observations on SCR & NR indicate improvement in overall track performance after the application of geogrid. Field observations on SCR & NR indicate improvement in overall track performance after the application of geogrid.

Geo-grid + Geotextile on IR NF Railway has tried use of Geo-grid (Polyester based – knitted & coated with strength of 40 kN/m & aperture size of 25mmx25mm) in combination of geo-textile and sand layer for formation rehabilitation. The performance report of the trial section is satisfactory. NF Railway has tried use of Geo-grid (Polyester based – knitted & coated with strength of 40 kN/m & aperture size of 25mmx25mm) in combination of geo-textile and sand layer for formation rehabilitation. The performance report of the trial section is satisfactory. For low density routes, geotextile along with sand layer and brick soling has been used in Sitamarhi – Darbangha project, ECR. For low density routes, geotextile along with sand layer and brick soling has been used in Sitamarhi – 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 ( ) 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- synthetics in IR Draft ‘Guidelines for use of Geo-synthetics on Indian Railways’ has been prepared by RDSO provisional specifications of various geosynthetics items based on relevant literature survey Draft ‘Guidelines for use of Geo-synthetics on Indian Railways’ has been prepared by RDSO provisional specifications of various geosynthetics items based on relevant literature survey Extended field trials on geogrid are being done on IR to validate & assess the specifications of geogrid. Extended field trials on geogrid are being done on IR to validate & assess the 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.

THANKS