Transcript Specifications and scope for use of geo
Geo-Synthetics Specifications for Railway Sector
Rajesh Agarwal,
Director, RDSO
RDSO – Research Design & Standard Organization Only R & D organization of IR Deals from Track formation to Bridges to Coaches to signal to OHE Made specifications of products for Railway Use Latest Achievements includes AC Double Decker Coach 4500 HP Hotel load locomotive Video Surveillances for running train Designing of Track including formation for HAL
Geotechnical Directorate
Deals with R & D of soil mechanics – for the use of Railways in
Formations Cuttings Ground improvement RE wall constructions ( ROB )
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)
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
Functions of Geosynthetics
Separation Filtration
Natural Soil Geo-textile Water Flow Direction Granular Soil
Functions of Geosynthetics
Reinforcement Drainage
Functions of Geosynthetics
Barrier
Scope for use of geosynthetics
Vision 2020
New Lines -- 25000 km route expansion DFC- Western & Eastern Corridor Double/Multiple lines – 30000 Kms
Need for Use of Geo-Synthetics
Existing Lines
• •
Indian Railways is upgrading infrastructure to meet future demand of growing traffic.
Geosynthetics can also rehabilitation/strengthening be used in of existing weak formation of length about 700 kms PR & 2000km TSR.
Scope for use of geosynthetics
ROB/RUB
Road Over Bridge ( 600 ROB constructed per year)
Application In Railway (General)
Steep Slope Construction ( Non Railway Loading) Construction of high banks on soft soil (PVD) Erosion control of slope Protection against rock falls
ROB for Road Loading
Use of Synthetic Geogrids for Erosion Control of Natural Existing Slopes
Construction of RE Embankment
Typical Cross Section of Embankment with Prefabricated Vertical Band Drains Initial Embankment Sand Blanket Soft Clay Layer Band drains Firm Soil
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Application In Railway (Specific)
Track Bed Design Reinforced Earth Embankment (Railway Loading ) Formation Rehabilitation
GEOSYNTHETICS APPLICATION IN RAILWAY FORMATION
USES OF GEO-GRID
GEOSYNTHETICS APPLICATION IN RAILWAY FORMATION
Geotechnical Directorate
Locations
Formations Cuttings Ground improvement RE wall constructions ( ROB)
Specification requirement
To be designed for Rly Loadings No issue with Rlys No issue with Rlys No issue with Rlys
Specifications and scope for use of geo-synthetics in World Railways
European Railways (UIC) Code 719 R
New Construction Geotextiles between blanket and prepared subgrade if prepared subgrade has fines more than 15%
Existing Track Geotextiles and geogrids for Formation Rehabilitation
Specifications and scope for use of geo-synthetics in World Railways
European Railways (UIC) Code 719 R
New Construction Geotextiles between blanket and prepared subgrade if prepared subgrade has fines more than 15%
Existing Track Geotextiles and geogrids for Formation Rehabilitation
Specifications and scope for use of geo-synthetics in World Railways
American Railways AREMA Manual Part 10
New Construction Geotextiles between Ballast & sub-ballast Geotextiles beneath sub-ballast Erosion Control on slopes
Existing Track For Formation Rehabilitation
Specifications and scope for use of geo-synthetics in World Railways
Australian Railways Reconditioning Guidelines RTS3430
Existing Track Geotextiles and Geogrids for Formation Rehabilitation
Specifications and scope for use of geo-synthetics
Indian Railways (specific to railway use)
Jute geotextiles ( for erosion control) Issued Geo-grids under trial Geotextiles (beneath track & slope protection) under preparation
Jute Geo-Textile
Guidelines for application of Jute Geo-textile in Railway Embankment & Hill slopes issued for erosion control.
Guidelines no. RDSO/2007/GE : G-0008
Use of IS of geo-synthetics by IR
Geo Jute All properties is to be checked with IS codes Properties
Weight (gsm) Maximum length & width Ends/dm & picks/dm Thickness Aperture size Minimum Breaking Load Maximum Elongation at Break
Test Method (IS)
IS: 2387 IS: 1954 IS: 1963 IS: 7702 IS: 2405 IS:1969 IS: 1969
Use of IS of geo-synthetics by IR
Geo Grid All properties is to be checked with IS codes Properties
Mass per unit area Ultimate Tensile Strength Load at 2% & 5% strain Strain at Ultimate Tensile Strength
Test Method (IS)
IS: 14716 IS: 13162 (Part V) IS: 13162(Part V) IS: 13162(Part V)
Use of IS of geo-synthetics by IR
Geo Textiles All properties is to be checked with IS codes Properties
Mass per unit area Tensile Strength Elongation at break Apparent opening size Water flow rate normal to the plane
Test Method (IS)
IS: 14716 IS 13162 IS: 13162 IS: 14294 IS: 14324
Geo-grid in IR
Biaxial geo-grid 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 Geo-grid.
Geo-grid+Geo-textile on IR
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.
For low density routes, geotextile along with sand layer and brick soling has been used in Sitamarhi – Darbangha project, ECR.
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)
Geo-grids
40X40 mm to 60X60 mm aperture size are not available for trial.
These sizes may be provided/manufactured.
Scope- Early Rehabilitation of approx.
2000 km track.
Specifications of Geogrids for Extended Trials on South Central Railway
Item
1
Property
Material of Geo grid 2 Aperture size (clear) 3 Roll width 4 Roll length
Test Method Values
• • Any organic polymer based material to provided required mechanical properties (like Polypropylene/Polyester/HDPE or similar polymer).
Atleast, both Polypropylene and Polyester geo-grid material must be used in trial.
1. 30-40 mm – Square (preferably 35mmx35mm) 2. 40-50 mm – Square (preferably 45mmx45mm) 3. 50-60 mm – Square (preferably 55mmx55mm) 4. 30-40 mm x 60-65 mm – Rectangular 5. 40-50 mm x 60-65 mm – Rectangular Aperture sizes of geo-grid of square/rectangular shape in each above group should differ atleast by 8-10mm.
As per requirement of width attachment to fit with BCM, in the range 3.8m to 4.0m.
50 m (Minimum)
Mechanical Properties & other Tests
Item Property Test Method Values
5.1
Ultimate Tensile Strength (MD & CD) IS: 13162 part 5 & IS: 13325/ASTM D 6637/BS EN ISO: 10319 Two types 1. 20 kN/m (minimum) 2. 30 kN/m (minimum) 8-5% (Range) 5.2
5.3
Strain at Ultimate Tensile Strength (MD & CD) Junction Efficiency (CD & MD) (Non Essential Test) IS: 13162 part 5 & IS: 13325/ASTM D 6637/BS EN ISO: 10319 GRI-GG2-87 and GRI GG1-87 Desirable 95% (Test to be done prior to insertion) Non Essential Tests : These tests are to be conducted on geo-grid samples before laying and test values are to recorded for further decision.
6.1
Radial stiffness at low strain (@0.5% strain)(Non Essential Test) ISO 10319: 1996
Item Property Test Method
6.5
6.6a
6.6b
6.7
Resistance to chemical degradation (Non Essential Test) Resistance to UV Light Weathering (Non Essential Test) Carbon Black Test (where applicable as per polymer type material) (Non Essential Test) Creep limited Strength for 15 years period at 30 ° C temp.
(MD & CD) (Non Essential Test) EPA 9090 ASTM D4355 BS2782 Part-4 Method, 452B: 1993 ASTM D 5262/ASTM D6992/ISO 13431
Values
Specification of Non-woven Geo-textile 36
SL
1 2 Polymer
Property
Weight/Mass per unit area 3 4 5 Roll Length Mechanical Properties 1 Thickness of Fabric at 2 Kpa Roll width Elongation at break
Test Method Values
Polypropylene/ High Density Polyethylene/ polyamide, polyester or similar polymer IS: 14716 / ASTM D: 3776 ASTM 5199 300 g/m2 (Minimum) 2.0 mm (minimum) 5.0 metre (minimum).
50 m (minimum) 2 Tensile Strength IS: 13162 / ASTM D 4595 / EN ISO: 10319 IS: 13162 / ASTM D 4595 / EN ISO: 10319 Hydraulic Properties 1 2 Apparent opening size O 95 Water Flow Rate Normal to the Plane IS: 14294 / ASTM D 4751 / EN ISO: 12956 IS 14324 / ASTM D 4491 40 % to 70 % 15 kN/m (minimum) 40 to 85 microns 20 lit. /m2/s (minimum)
Specification of woven geo-textile
SL
1 2 3 4 5 Polymer Warp Weft
Property
Mass per unit area Thickness at 2 Kpa Roll width Roll Length Mechanical Properties 1 Tensile Strength
Test Method Values
Polypropylene/ High Density Polyethylene/ polyamide/ polyester or similar polymer IS: 14716 / ASTM D: 3776 ASTM: 5199 5.0 metre (minimum) 50 m (minimum) IS: 1969 / ASTM D 4595 / EN ISO: 10319 2 3 Elongation at Maximum Load Warp Weft Puncture Strength IS: 1969 / ASTM D 4595 / EN ISO: 10319 IS: 13162 / ASTM D: 4833 37 Hydraulic Properties 1 2 Apparent opening size O 95 Water Flow Rate Normal To The Plane IS 14294 / ASTM D: 4751 / EN ISO: 12956 IS: 14324/ ASTM D: 4491 240 g/m2 (Minimum) 0.65 mm (minimum) 40kN/m (Minimum) 35kN/m (Minimum) 15%-30 % 15%-30 % 600 N (Minimum) 425 microns (maximum)
Geotechnical Engg./RDSO
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)
Road Over Bridge without Reinforced Earth Wall (Conventional ROB)
Road Over Bridge With Retaining Wall
Road Over Bridge With Reinforced Earth Wall
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
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
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.
Draft Guidelines For Geo-synthetics Prepared & under active discussion with in Railway
THANKS
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.
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
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.
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.
Need for Use of Geo-Synthetics
• • •
New Constructions To construct ‘ Dedicated Freight Corridors i.e. Eastern Corridor & Western Corridor’ & ‘ High Speed Corridors to connect the major cities .
’ This requires construction of new stable track formations suitable for heavy axle loads. It is difficult to adopt the present practice in DFC & High speed which will increase the maintenance cycles. Hence Railway formation should be design using geo-synthetics
.
Specification of Geo-grid
SN
1 2.
3.
Polymer Mass per unit area Aperture size
Property Test Method Values
Polypropylene/Polyester or similar polymer IS: 14716 / ASTM D: 3776 320 g/m 2 (minimum) Square opening of suitable size (suggested size 35mm to 60 mm) such that effective interlocking takes place with the existing ballast particles. (Size to be decided by PCE Zonal railway, as per site conditions.) As per site requirement and width attachment to BCM 50 m (minimum) 4.
Roll width 5.
Roll Length
Mechanical Properties
1.
Ultimate Tensile Strength (MD) 2.
3. Ultimate Tensile Strength (CD) Strain at Ultimate Tensile Strength (MD) Strain at Ultimate Tensile Strength (CD) Creep limited strength for 15 years period at 30 0 C temperature (MD and CD) IS: 13162 part 5 & IS: 13325 / ASTM D 6637 / BS EN ISO: 10319 IS: 13162 part 5 & IS: 13325 / ASTM D 6637 / BS EN ISO: 10319 ASTM D5262 / ASTM D6992 / ISO 13431 30 kN/m (minimum) 30 kN/m (minimum) 8 - 15% 8 - 15% 15 kN/m (minimum)
Note: 1. Test method is only indicative which give procedure. However values will govern as
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specified above.
2
. Long term strength of geogrid with due consideration of creep effect is important as geogrid is supposed to remain under track for long period say 20 years or more.
3. MD stands for Main Direction & CD stands for Cross Direction.
Engg./RDSO