Keeping on Track with Geosynthetics 15th April 2021 - Pete Stevens UK Chapter of the International Geosynthetic Society - Peter Stevens

Keeping on Track with Geosynthetics
15th April 2021

                UK Chapter of the International
 Pete Stevens   Geosynthetic Society

Who are we?

•   UK Brand leader
•   UK manufacturer
•   50 years track history
•   Global distribution
•   Approved products

Agenda


 Track   history

 Introduction      to geosynthetics

 Problems    and solutions

 Testing   and case studies

 Benefits


 Summary

Track History
                        
   1818 Institute of Civil Engineers
                        
   1825 Stockton & Darlington Railway
                        
   1857 First Steel Rails Derby Station
                        
   1884 Permanent Way Institution
Tracktex installation

                        
   1914 20,000 miles track
                        
   1948 British Rail
                        
   1950’s Diesel and electric trains

Track History
                        
 1963Beeching Report (5,000 miles track
                         and 2,363 stations closed)
                        
 1970   Geotextiles
Tracktex installation

                        
 1976   High Speed Train (148mph)
                        
 1980   Geogrids (Silkstone Colliery)
                        
 1983   International Geosynthetics Society

Track History
                        
   Early 1990’s Geocells (Northumberland)
                        
   1994 Privatisation (Railtrack)
                        
   1996 TRK/010 geotextiles specification
Tracktex installation

                        
   2000 Hatfield derailment
                        
   2001 Network Rail
                        
   2010 SBR Geocomposites

Keeping on track
                        
 10,000   miles of track in the UK
                        
 Lower   maintenance
                        
 Lower   Cost
Tracktex installation

                        
 Lower   Carbon
                        
 Resilience

Introduction to Geosynthetics
ISO 10318 Definition: geosynthetic
Generic term describing a product, at least one of whose
components is made from a synthetic or natural polymer, in the
form of a sheet, a strip, or a three-dimensional structure, used
in contact with soil and/or other materials in geotechnical and
civil engineering applications

Functions of Geosynthetics

   
 Separation
   
 Filtration
   
 Drainage
   
 Reinforcement
   
 Stabilisation
   
 Barrier
   
 Protection
   
 Erosion Control

Separation   Geotextiles

Filtration   Geotextiles

Drainage   Geocomposites

Reinforcement
            Geogrids, geotextiles

Stabilisation
                Geogrids, geocells

Barriers
           Geomembranes

Protection
             Geotextiles

Erosion Control   Geocells, geomats

Typical Trackbed Construction

Ballasted vs slab track


   Low investment         
   High investment

   Easy to lay            
   Low maintenance

   High maintenance       
   Passenger comfort

   Good drainage          
   Noise

   Passenger comfort
                           
   ~60 year design life

   Noise
                           
   High Speed

   ~20 year design life
                           
   High stiffness

   Speed limited
                           
   Improvements limited

   Lower stiffness

   Dust

Maintenance of ballasted track

Problems and Solutions with
geosynthetics

Ballasted Track Problems
Sub grading pumping (wet beds)   Ballast abrasion

Poor drainage                    Very soft subgrade

Possible Causes

   Weak and or variable ground conditions (subgrade)

   Insufficient drainage

   Severe subgrade erosion

   Insufficient filtration in sub-ballast

   Ballast too thin + overstressed

   Fouled/contaminated ballast

   Rapid transitions of subgrade stiffness (S&C, structures…etc…)

Can geosynthetics solve these problems?
 Sub grading pumping (wet beds)   Ballast abrasion

  Poor drainage                   Very soft subgrade

YES!
Sand blanket replacement geocomposite   Geogrid Ballast stabilisation

                                        Geocell sub ballast stabilisation

  Drainage trench filtration

Geosynthetic Track
          Formation Products
                               PW9
PW1          PW2

  PW4LA            Hydrotex™

Track Formation Geosynthetics
Geosynthetic                  Function

Normal Geotextile             Separation and filtration
separator

Robust geotextile separator Separation and filtration

Biaxial and triaxial geogrids Stabilisation

   Stabilising
   eogrids
Geocells                      Stabilisation

Geocomposites                 Separation, filtration,
                              stabilisation, drainage

Sand blanket replacement      Separation and (micro)
geocomposite (SBRG)           filtraton

Problem 1 – wet beds

Traditional solution

Geosynthetic solution

100mm Sand blinding installation

Geotextile Installation

2011 Testing of SBRG

 Test cell at The University of Birmingham.


 Enable samples to be tested under cyclic
  loading conditions that simulate those at
  the ballast subgrade interface.


    The design of the cell permits
    settlement to occur without the loss of
    contact between the composite and the
    subgrade.


   Load is applied in the form of a sine
    wave, applied at 3Hz

Hydrotex – liquid passed

2013 Separation & Filtration
         Monks Lane, UK

2013 Separation & Filtration
         Monks Lane, UK

2014 - Big Rig testing

2014 Testing of SBRG
 
   Big rig test University of Birmingham
 
   Large 1.0m x 1.5m sample
 
    Cyclic load applied at 2Hz 10 to 125kN
 
    3.8M cycles

Subgrade at end of test

BENEFITS

Faster installation Time

100+% more with SBRC than 100mm sand
blinding in 24 hour possession
            Tracktex installation

Less deliveries
1 lorry 20Tn sand - 30Lm track
1 lorry 48 rolls SBRC – 1,200Lm track
         30 linear m of sand blanket

40 lorries vs 1

                  =

Cost Savings

 £1.5M saving per year
 by using SBRC instead
 of a 100mm thick sand
   blanket (based on
20km of renewed track)

Carbon Savings
• 20% saving using SBRC instead of
       a 100mm sand blanket

• 5kg CO2e per SQM spoil removal
      and importation of sand

   • 3.9kg CO2e per SQM SBRC

  Source: EA Carbon calculator v
  3.1.2 and Raja et al paper 2015

Problem 2 – high maintenance

Stabilisation with geogrids
Ballast stabilisation - UK experience
Ballast stabilisation: Maintenance at Coppull Moor, UK
(2005)
                               
 Reconstruction on UK main
                                   line
                                 
 Investigation of deformation
                                   before and after installation
                                   of stabilisation geogrid

  
 FWD Testing
  
 Dynamic test 30 ms impulse
  
 Single unclipped sleeper
  
 Simulates high speed axle
  
 Rapid testing immediate
    results
  
 Stiffness of all track bed
    layers

Stabilisation with geogrids
Ballast stabilisation: Maintenance at Coppull Moor, UK
(2005)
                                                             Year
                           1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
                           0

                           1
 Deviation over 35m (mm)

                           2

                           3
                                                                                        Geogrid installed
                           4                                               Deflection
                                                                           0.5 mm/yr
                           5                                               1.5 mm/yr
                                                                           Limit for speed restrictions
                           6
                               Ch 10 miles 220 yds to 440 yds

Stabilisation with geogrids
Ballast stabilisation - UK experience
Ballast stabilisation: Maintenance at Coppull Moor, UK
(2005)
                                                             Year
                           1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
                           0

                           1
 Deviation over 35m (mm)

                           2

                           3
                                                                                        Geogrid installed
                           4                                               Deflection
                                                                           0.5 mm/yr
                           5                                               1.4 mm/yr
                                                                           Limit for speed restrictions
                           6
                               Ch 10 miles 440 yds to 660 yds

Stabilisation with geogrids

   Extend maintenance periods x3 in soft formations

   Reduces tamping and extends ballast life

   Thickness reductions

Problem 3 – very soft subgrade

Stabilisation with geogrids
Ballast stabilisation - UK experience
Sub-ballast stabilisation Deutsche Bahn, Cologne (2003)

Stabilisation with Geogrids


   Replacement of existing track

   Higher standards required

   Original design required 1.05m thick sub-ballast

   Alternative reinforced with geogrid and geotextile
    composite

   Sub-ballast thickness reduced to 0.7m

   Design carried out using EV2 method

Stabilisation
 The inclusion of a geosynthetic to stiffen the aggregate layer
 can result in aggregate, excavation and disposal savings.

STIFFER       Stabilised
COMPOSITE
MATERIAL      Aggregate                   Non-stabilised
                                            Aggregate

              Subgrade
                                             Subgrade

Stabilisation - Benefits

   If we extrapolate the 350mm depth saving to a 1km long track
    4m width we save:
•   1400m3 of excavation and disposal which equates to
    approximately 100 eight wheel tipper truck movements

                             The geogrid
                                will
                                  200be
                             delivered
                               TRUCKSon
                              one truck

•   Add the same again for 1400m3 of imported aggregate

•   Plus the energy expended in excavation and placement

•   Its easy to see how geosynthetic technology offers highly
    sustainable solutions

Stabilisation with Geocells
Sub ballast stabilisation: Northumberland, UK (1992?)

                                •   ECML, Newham bog
                                •

Stabilisation with Geocells
Sub ballast stabilisation: Northumberland, UK (1992?)

                                      
   Geocomposite
                                          drainage layer
                                      
   2 layers of
                                          Geocells
                                      
   Speed increased
                                          to 125mph

GEOSYNTHETICS BENEFITS SUMMARY
•   Extend maintenance periods x3 in soft formations
•   Reduces tamping and extends ballast life
•   Sub-ballast thickness reductions

Acknowledgements

Future events…

   UK arm of the International Geosynthetics Society


   Evening Lectures (on line)

   March 9th 5pm - Geosynthetics in Hong Kong
    Landfills by John Cowland

   April 22nd 6pm – LCA of geosynthetics vs
    conventional construction methods by Henning
    Ehrenberg


   Free Membership for Students

   Sign up today! www.igs-uk.org

REFERENCE DOCUMENTS

•   1996 NR/SP/TRK/010       Geotextiles
•   2005 NR/SP/TRK/9039 Formation Treatments
•   2015 NR/L2/TRK/4239 Track Bed Investigation,
    Design and Installation (Replaces above)
•   2016 A Guide to track stiffness Powrie & Le Pen
•   2017 PME080217       NR Track and Lineside
    Geosynthetics specification

Thank you and questions?

  Pete Stevens B Eng (Hons)
  Applications Development Manager
  M +44 (0)7811 392263
  pete.stevens@terram.com