Geo-Synthetics Perspective in Railway Sector

1. Geo-Synthetics Perspective in Railway Sector Rajesh Agarwal Director RDSO

2. RDSO – Research Design & Standard Organization • Only R & D organization of IR • Deals from Track formation to Bridges to Coaches to signal to OHE • Latest Major Achievements includes • AC Double Decker Coach • 4500 HP Hotel load locomotive • Video Surveillances for running train • Designing of Track including formation for HAL

3. Geotechnical Directorate Deals with R & D of soil mechanics – for the use of Railways in Formations Cuttings Ground improvement RE wall constructions ( ROB )

4. Introduction Geosynthetics :Generally Polymer based - Polypropylene, Polyester, PVC, Polyamide, Polyethylene Various types of Geosynthetics can be used in Railways Geotextiles Geogrids Geonets Geocell Geomembranes Geocomposites Prefabricated Vertical Drains (Band Drains)

5. Functions of Geosynthetics Geo-synthetics can perform one or several functions to improve mechanical or hydraulic behaviour of the Railway Formations (Base structure) The basic functions performed by geo-synthetics are: Separation Filtration Drainage Reinforcement Barrier Basal Layer

6. Scope for use of geosynthetics Vision 2020 New Lines -- 25000 km route expansion DFC- Western & Eastern Corridor Double/Multiple lines – 30000 Kms

7. Need for Use of Geo-Synthetics Existing Lines • Indian Railways is upgrading infrastructure to meet future demand of growing traffic. • Geosynthetics can also be used in rehabilitation/strengthening of existing weak formation of length about 700 kms PR & 2000km TSR.

8. Scope for use of geosynthetics ROB/RUB Road Over Bridge ( 400 ROB constructed per year)

9. Steep Slope Construction ( Non Railway Loading) • Embankment Slip repairs • Construction of high banks on soft soil (PVD) • Erosion control of slope • Protection against rock falls

10. Use of Synthetic Geogrids for Erosion Control of Natural Existing Slopes

11. Construction of RE Embankment

12. Typical Cross Section of Embankment with Prefabricated Vertical Band Drains Sand Blanket Initial Embankment Band drains Soft Clay Layer Firm Soil 12

13. Track Bed Design • Reinforced Earth Embankment (Railway Loading ) • Formation Rehabilitation

14. GEOSYNTHETICS APPLICATION IN RAILWAY FORMATION USES OF GEO-GRID

15. GEOSYNTHETICS APPLICATION IN RAILWAY FORMATION

16. 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) has been used for formation rehabilitation/strengthening. • Observations in field at SCR & NR have indicated improvement of overall track performance after the application of Geogrid.

17. Geo-grid+Geotextile on IR For low density routes, geotextile along with sand layer and brick soling has been used in Sitamarhi – Darbangha project, ECR. • NF Railway also 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 of NF Railway is satisfactory.

18. Geo-grids • Field trials for formation rehabilitation Geo-grid in SCR • Issues involved for optimum benefit • Aperture size ( As per ballast size if IR) • Junction strength (As per Axle load) • Material type (As per Soil/Atmospheric condition)

19. Geo-grids 40X40 mm To 60X60 mm aperture size are not available for trial These sizes may be provided/manufactured. Scope- Early Rehabilitation of app 2000 km track.

20. Reinforced Earth Design for Railway Loading • By KRCL in USBRL Projects • Bridge no 40 at Riasi • Bank of 16m to 56 m high • Design Approved by IIT/D • Cost effective (whether or not)

21. Road Over Bridge without Reinforced Earth Wall (Conventional ROB)

22. Road Over Bridge With Retaining Wall

23. Road Over Bridge With Reinforced Earth Wall

24. General Issues • Specification- Generic in nature • To avoid monopoly • Material to be readily available (Time constraint) • Cost effective • Should be competitive with Alternates • Research with Blending of Jute with PP etc. being explored by Railways

25. Issues concern • Testing facilities • Contracts to be awarded division wise & to be passed by divisional authorities • How testing of material to be monitored • Works contract/Supply contract • Railway prefers works contract

26. Project on Application of Geo-syntheticis • Analysis of behavior of different Geo-synthetics to be used in Railway Formations • Validation through Lab model, • FEM model • And site measurements etc.

27. RDSO has drafted the Specification for geo-synthetics which is under active consideration of Railways

28. THANKS

29. Other Use Of Geosyntheticis in IR • Different Zonal Railways may be use the Geosynthetic on their railway as per requirement and site conditions such as: • Steep Slope Construction, Embankment Slip repairs, Construction of high banks on soft soil (PVD), Erosion control of slope And Protection against rock falls etc.

30. Formation treatment with blanket & geotextile by formation rehabilitation m/c • The limitations of Indian railways • The formation rehabilitation m/c very costly • Line Block Requirement - 6 to 8 Hrs. • (Very difficult for running track) • Progress very slow- 300 to 400 m per day • Geotextile life is very short 4 -5 years, Indian Railway want long life such as 10 to 15 years. • Cost effectiveness - Cost consideration not match

31. QUALITY ASSURANCE & QUALITY CONTROL PLAN FOR GEOSYNTHETICS • The manufacturer must have in house integrated testing facilities for all the tests as per specifications to be carried out on the product. The testing facilities may be more for Geosynthetics in India. • The Railway Authorities may witness the tests carried out at independent testing facilities.

32. CONCLUSIONS • Geo-synthetics can be used effectively in railway application for track bed stabilization, track drainage, erosion control, interface protection, construction over soft soil, steep slope construction, mud pumping, etc. • Its use is a necessity and cost effective for construction of new formations & rehabilitate / strengthen the existing formations for running of heavy axle loads. • The specifications of Geosynthetics items specially Geogrid for railway application are in evolving stage worldwide. • IR has gained some experience and RDSO has framed provisional specifications. These should be tried as per site conditions. • Extended Field trials are necessary to validate & assess specifications of geogrids for track bed strengthening.