SMART - Supplementary Methods of Analysis for Rail Track

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2 SMART - Supplementary Methods of Analysis for Rail Track

3 SMART Development 1. Implications of track problems and related maintenance issues facing rail industry;. The need for simple and systematic tool for design and analysing track, and practice guides for maintenance; 3. Wealth of available large-scale experimental and field data over 15 years of ARC and CRC-Rail research projects Ballast Crushing Foundation soil liquefaction Coal fouling Poor Drainage Differential settlement Flood Damage 3

4 4 What is SMART? A set of supplementary MATLAB subroutines to aid the design and analysis of track substructure based on research outcomes; Collection of performance-based tools for the analysis of track substructure (i.e. ballast, subballast and subgrade). A stand-alone computational software with user-friendly interfaces for data input and output. It is not a substitute for primary or conventional design methods such as FEM or DEM numerical software, but is meant to be supplementary and complimentary for more advanced track design, construction and management.

5 History of SMART : ARC-SPIRT project on Rail Ballast with SRA and the development of large scale PST rig : SMART evolved as a 'hobby' by Prof. Buddhima Indraratna through simple EXCEL spreadsheets with basic elastic analyses plus Li & Selig (1998) method. 000: ARC-Linkage project with RIC : 1 st CRC-Rail successful bid and the inception of industry-driven research : First basic MATLAB program developed by A/Prof. Hadi Khabbaz - more efficient than EXCEL : Selected UOW research outcomes added, based on the outcomes of TWO ARC-Linkage projects with RIC (now RailCorp). Inclusion of fundamental static and cyclic stress-strain behaviour PhD work of Dr. Daniela Ionescu and Dr. Wadud Salim : Two major projects under 1 st CRC for Railway Engineering Particle Breakage module developed through PhD work of Dr. Joanne Lackenby.

6 6 History of SMART cont : ARC Discovery project on Cyclic Densification and Breakage (project CI: Prof Indraratna; Research Associate: Dr Cholachat) 007: Start of CRC for Rail Innovation : CRC for Rail Innovation - Projects R3.106 & R3.117 (Project leader Prof. Indraratna, Research Associates Dr. Sanjay Nimbalkar and Dr. Pongpipat) : Dr. Sanjay Nimbalkar injects more modules on cyclic stress analysis and particle breakage : 1 st draft of SMART Manual completed by Dr Pongpipat : Modules of Drainage, Filtration, Fouling and Geosynthetics added CRC-Rail work of 5 PhD students: Dr Ashok Raut, Dr Dominic Trani, Dr. Nayoma Tennakoon, Dr. Khaja Karim Hossein and Dr. Trung Ngoc. 01: Dr. Nayoma Tennakoon takes over final stages of SMART development and completion of Manual : Further calibration of SMART with Singleton project (R3.117) data

7 Project Leader: Prof Buddhima Indraratna Project Chair: Mr Tim Neville A/Prof Cholachat Rujikiatkamjorn Research Fellow for Project R3.117: Dr Nayoma Tennakoon Research Fellow for Project R3.106: Dr Sanjay Nimbalkar Dr Sakdirat Kaewunruen Mr David Christie Mr Mike Martin 7

8 8 New Computational Procedure UOW Recommended Approach 1. Compute the optimum thickness of substructure layers. Estimate track settlement for given loading & geotechnical conditions 3. Assess the role of ballast fouling and track drainage 4. Implications on train speed reduction 5. Use of geosynthetics for increased track stability 6. Use of subballast as a filter

9 9

10 Large-scale Triaxial Rigs Built at UoW Prismoidal Triaxial Rig to Simulate a Track Section (Specimen: 800x600x600 mm) Cylindrical Triaxial Equipment (Specimen: 300 mm dia.x600 mm high) 10

11 Effect of Confining Pressure on Particle

06 (Cyclic Loading) Ballast Breakage Index (BBI)

0 0 Unstable Dilation Zone Optimum Degradation Zone

11 11 Effect of Confining Pressure on Particle Degradation 0.06 (Cyclic Loading) Ballast Breakage Index (BBI) Indraratna, Lackenby and Christie (005) Geotechnique, ICE, UK. Vol. 55(4), Ballast Breakage Index, BBI Unstable Dilation Zone Optimum Degradation Zone Optimum Contact (I) (II) (III) q max = 500 kpa q max = 30 kpa Compressive Stable Degradation Zone Effective Confining Pressure (kpa)

12 1 Effect of Confining Pressure on Ballast Breakage UoW Test Data Lackenby, J., Indraratna, B., McDowell, G. R. & Christie, D., (007). Geotechnique 57, No. 6,

13 Bearing Capacity of Ballast q ult = N S ( 0.5γB U γ γ ) ( 1) tan( 1.4φ ) Nγ = N q ( ) Sγ = Kp B/ L Rail Gauge Qult Rail Sleeper Ballast Subballast/ Structural fill Rail Pad tan Nq = Kpe π φ Subgrade K p 1+ sinφ = 1 sinφ q ult = Ultimate Bearing Capacity of granular media S γ, N γ, N q = bearing capacity factors k p = passive earth pressure coefficient 13

14 Bearing Capacity of ballast 14

15 Constitutive Modelling incorporating Particle Breakage 15 Before Loading Voids Asperity wear After Loading New hairline micro-cracks Ballast Broken particles fill voids (fouling) Sharp corners broken off

16 Detailed Design Features: e.g. Ballast Breakage Ballast Model Indraratna and Salim, 00; Salim and Indraratna,

17 17 Particle Size Distribution Ballast Gradation

18 Ballast Breakage Indices 18

19 19 Granular Layer Thickness Assessment Granular Layer Thickness Li & Selig Talbot Boussinesq SMART Recommended Approach

20 Design of Granular Layer Thickness 0

Subballast Filtration Terzaghi s filter design criteria UOW Constriction Size Distribution (CSD) method (Raut & Indraratna, 008) 0.

21 Subballast Filtration Terzaghi s filter design criteria UOW Constriction Size Distribution (CSD) method (Raut & Indraratna, 008) v k j i v k j i D D D D D D D D ( ) ( ) ( ) rk k rj j ri i v P P P P =!!r r!r 3! k j i ( )( ) n i D D R n i D D i VMD i VLD d VMD i i v,..., 1,, 1,,, = + = < d D d D 1 * < d D c D c35 is the constriction size which is finer than 35% based on CSD curve d * 85 is the base soil size based on a surface area finer that 85%. 1

22 Subballast filtration

Fouling and Drainage Hydraulic Conductivity, k (m/s) 10 0 10-1 10-10 -3 10-4 10-5 10-6 Coal-fouled ballast: Experimental Coal-fouled ballast: Theoretical Sand-fouled ballast: Experimental Sand-fouled

23 Fouling and Drainage Hydraulic Conductivity, k (m/s) Coal-fouled ballast: Experimental Coal-fouled ballast: Theoretical Sand-fouled ballast: Experimental Sand-fouled ballast: Theoretical Bellambi Site VCI=33% hydraulic conductivity of coal fines hydraulic conductivity of clayey fine sand Rockhampton Site VCI=7% Sydenham Site VCI=% Large-scale permeability test apparatus Void Contaminant Index, VCI (%) Hydraulic Conductivity (k) of fouled ballast VCI = ( 1+ e e b f ) G G sb sf M M f b 100 k b = Hydraulic conductivity of clean ballast = Hydraulic conductivity of fouling material Tennakoon, Indraratna, Cholachat, Nimbalkar and Neville (01) ASTM Geotechnical Testing Journal, 35(4): 1-1 k f 3

24 Effect of Fouling on Speed Reduction 4 (a) P s = 1.3 kn (b) P s = 147. kn

25 Permeability and Track Drainage 5

26 Speed Reduction vs. Fouling 6

27 Use of Geosynthetics Geogrid layer placed above the capping Ballast placement over the geocomposite Bonded Geogrid-geotextile Woven Geotextile OK between subballast and subgrade 7

28 Use of Geosynthetics in Tracks 8

29 9 SMART User Manual Operational flowchart of SMART Introduction Installation and getting started Input of data Presentation of results Step-by-step design examples Descriptions of program components References

30 Acknowledgment CRC for Rail Innovation Technical staff at UOW (Alan Grant, Ian Bridge, Cameron Neilson) SC members (Sydney Trains, ARTC, Aurizon) Past and current PhD students ARC Rail CRC 30

31 Thank you!

32 Ballast Constitutive Model with Breakage ( ) ( ) = M M M p B M M M d d p s p v * 3 9 * * η η µ χ η η ε ε ( ) ( ) ( ) ( ) { } = * * * ) ( ) ( η µ χ η η η η ακ ε M p B M p p e M d M M p p p p d o i i cs i o cs p s Plastic Flow rule for computing strains ( )( ) constant ln ) ( ) ( = + + = M M M p p B i i cs β o a b A B p q 1 M Critical state line Constant stress ratio yield loci Yield surface at stress state 'a' M - η * ln(p cs(i) /p (i) )(db g /dε s p ) Fresh ballast (Bombo, NSW) ln(p cs(i) /p (i) ) (db g /dε sp ) = χ + µ(m-η*) σ 3 = 300 kpa σ 3 = 00 kpa σ 3 = 100 kpa σ 3 = 50 kpa Breakage parameters 3 Salim, W. and Indraratna, B. (004) : Canadian Geotechnical Journal, Vol. 41, No. 4, pp

Design of Granular Layer Thickness (Li & Selig, 1998 Method) Granular layer Subgrade Soil Type a b m CH (high plasticity clay) 1.0 0.18.40 CL (low plasticity clay) 1.10 0.16.

33 Design of Granular Layer Thickness (Li & Selig, 1998 Method) Granular layer Subgrade Soil Type a b m CH (high plasticity clay) CL (low plasticity clay) MH (high plasticity silt) ML (low plasticity silt) E b = 80 MPa Subgrade strain influence factor, I ε Subgrade deformation influence factor, I ρa 33

34 34 Stress Computations (Analytical and Empirical Methods) ε Boussinesq (1885) - Elastic Theory z x y Q o z A da η σ z x σ z y η-y (a) (b) Talbot (1919) - Semi-empirical method

35 35 Equivalent Elastic Modulus (EEM) of Granular Layer (UOW recommended approach) T E = Ballast E 1 T 1 T E T T E + T T E 3 3 Subballast /Capping E E 3 T Structural Fill T 3 Subgrade Combine the selected stress computation approach with the EEM approach

/k 300 Acceptable drainage 300< k b /k 3000 Poor Drainage 3000< k b /k 300,000 Very poor drainage

36 Relative Hydraulic Conductivity Drainage Criteria-Clay fouled ballast Drainage condition Relative hydraulic conductivity Free drainage k b /k 3 Very good drainage 3< k b /k 30 Good drainage 30< k b /k 300 Acceptable drainage 300< k b /k 3000 Poor Drainage 3000< k b /k 300,000 Very poor drainage 300,000< k b /k 30,000,000 Relatively Impervious k b /k 30,000,000 Drainage Criteria-Coal fouled ballast 36

37 Use of geosynthetics in track Indraratna et al., 01 A typical bonded geogrid Interface efficiency factor (α) 37

38 Increasing Confining Pressure using: Intermittent Lateral Restraints or Embedded Winged Sleepers Intermittent lateral restraints Lateral restraints Winged sleepers Rail Sleepers Lackenby, Indraratna, McDowell and Christie (007) Geotechnique, ICE, UK. Vol. 57(6),

39 Ballast Crushing Foundation soil liquefaction Coal fouling Poor Drainage Differential settlement Flood Damage 39

40 CRC Project R3.106 Ballast Breakage during High Impact Loads Singleton Field Trial, Feb. 010 Subgrade type Location of shock mat Without shock mat Ballast Breakage Index (BBI) Stiff Soft With Shock mat Stiff Above ballast Stiff Below ballast 0.19 Stiff Above & below ballast Soft Above ballast Soft Below ballast Shock Mat Soft Above & below ballast 0.08

41 Role of Geosynthetics on Track Deformation: Bulli Field Trial near Wollongong Plastic Geogrid and Drainage Fabric before ballast placement Ballast placement over the geocomposite 8 October 006 Ballast-geogridsleeper interaction Completed Section of Bulli

42 From Theory to Practice: Performance Monitoring at Singleton near Newcastle Geogrid layer placed above the capping Settlement pegs placement in the track Pressure cells below the sleeper Mudies Creek Bridge pressure cells

43 Average vertical deformation of ballast, (S v ) avg (mm) Deformation Response of Ballast Indraratna et al. (010). JGGE, ASCE, 136(7): Indraratna et al. (014). Ground Improvement, 167(1): 4-34 Bulli Track Number of load cycles, N 0 1x10 5 x10 5 3x10 5 4x10 5 5x10 5 6x10 5 7x10 5 8x10 5 9x Fresh Ballast (uniformly graded) Recycled Ballast (broadly graded) Fresh Ballast with Geocomposite Recycled Ballast with Geocomposite time, t (months) x x x10 5.0x10 5.5x10 5 The recycled ballast performed well because, it was broadly graded compared to the relatively uniform fresh ballast Average vertical strain of ballast, (ε 1 ) avg (%) Vertical Deformation of Ballast, S v (mm) Type of Section Aperture Size (mm) 6 Geogrid Geogrid Geogrid Geocomposite Singleton Track Time, t (days) Number of Load Cycles, N Optimum aperture size of geogrids is about 1.15D 50 of ballast. CRC Project R3.106 CRC Project R3.117 Vertical Strain of Ballast, ε v (%) 6

Ground Improvement in Transport Geotechnics - from Theory to Practice

Ground Improvement in Transport Geotechnics - from Theory to Practice Prof. Buddhima Indraratna Professor of Civil Engineering & Research Director Centre for Geomechanics and Railway Engineering Program