Ballast Railroad Design: SMART-UOW Approach Smart-uow Approach

The rail network plays an essential role in transport infrastructure worldwide. A ballasted track is commonly used for several reasons, including economic considerations, load bearing capacity, rapid drainage and ease of maintenance. Given the ever-increasing demand for trains to carry heavier axle loads at greater speeds, traditional design and construction must undergo inevitable changes for sustainable performance. Ballast is an unbounded granular assembly that displaces when subjected to repeated train loading affecting track stability. During heavy haul operations, ballast progressively deteriorates and the infiltration of fluidized fines (mud pumping) from the underlying substructure and subgrade decreases its shear strength and also impedes drainage, while increasing track deformation and associated maintenance. Features: serves as a useful guide to assist the practitionerin new track design as well as remediating existing tracks. research discussed in this book has made considerable impact on the railway industry. resulting from collaborative research between academia and industry, incorporating sophisticated laboratory tests, computational modelling and field studies. This book presents a comprehensive procedure for the design of ballasted tracks based on a rational approach that combines extensive laboratory testing, computational modelling and field measurements conducted over the past two decades. Ballast Railroad Design: SMART-UOW Approach will not only become an imperative design aid for rail practitioners, but will also be a valuable resource for postgraduate students and researchers alike in railway engineering.

1 Introduction 1.1 General background 1.2 Limitations of current track design practices 1.3 New developments in SMART-UOW approach 1.4 Scope 2 Parameters for track design 2.1 General background 2.2 Typical ballasted track problems 2.3 Typical input parameters for track design 2.4 Substructure of ballasted tracks 2.5 Ballast 2.6 Sub-ballast, subgrade/formation soils 2.7 Geosynthetics 2.8 Design criteria 2.9 Traffic conditions 2.10 Rail and sleeper properties 3 Bearing capacity of ballasted tracks 3.1 Introduction 3.2 Calculation of design wheel load (P) 3.3 Calculation of maximum rail seat load 3.4 Calculation of ballast/sleeper contact pressure 3.5 Bearing capacity of ballast 4 Thickness of granular layer 4.1 Introduction 4.2 Procedure to determine the thickness of ballast and capping layer 4.3 Equivalent modulus and strain analysis 4.4 Determination of track modulus 4.5 Determining the resilient modulus of ballast, MR 5 Effect of confining pressure and frequency on ballast breakage 5.1 Introduction 5.2 Determination of ballast breakage 5.3 Influence of confining pressure on ballast breakage 5.4 Influence of frequency on ballast breakage 5.5 Volumetric behaviour of ballast under monotonic and cyclic loading 6 Impact of ballast fouling on rail tracks 6.1 Introduction 6.2 Quantifying of ballast fouling 6.3 Relation among fouling quantification indices 6.4 Influence of ballast fouling on track drainage 6.5 Fouling versus operational train speed 6.6 Determining VCI in the field 7 Application of geosynthetics in railway tracks 7.1 Types and functions of geosynthetics 7.2 Geogrid reinforcement mechanism 7.3 Use of geosynthetics in tracks – UOW field measurements and laboratory tests 7.4 Measured ballast deformation 7.5 Traffic-induced stresses 7.6 Optimum geogrid size for a given ballast 7.7 Role of geosynthetics on track settlement 7.8 The effect of coal fouling on the load-deformation of geogrid-reinforced ballast 8 UOW – constitutive model for ballast 8.1 Introduction 8.2 Stress and strain parameters 9 Sub-ballast and filtration layer – design procedure 9.1 Introduction 9.2 Requirements for effective and internally stable filters 9.3 Filter design procedure 10 Practical design examples 10.1 Worked-out example 1: calculate the bearing capacity of ballasted tracks 10.2 Worked-out example 2: determine the thickness of granular layer 10.3 Worked-out example 3: ballast fouling and implications on drainage capacity, train speed 10.4 Worked-out example 4: use of geosynthetics in ballasted tracks 10.5 Worked-out example 5: evaluation of track modulus and settlement 10.6 Worked-out example 6: determine the friction angle of fouled ballast 10.7 Worked-out example 7: determine the settlement of fouled ballast 10.8 Worked-out example 8: calculate the ballast breakage index (BBI) 10.9 Worked-out example 9: effect of the depth of subgrade on determine thickness of granular layer 10.10 Worked-out example 10: design of sub-ballast/capping as a filtration layer for track 11 Appendix A: Introduction of SMART tool for track design 11.1 Introduction 11.2 Practical design examples using SMART tool 12 Appendix B: Unique geotechnical and rail testing equipment at the University of Wollongong

Buddhima Indraratna is Professor of Civil Engineering at the Centre for Geomechanics and Railway Engineering at the University of Wollongong, Australia. Trung Ngois Research Fellow at the School of Civil, Mining and Environmental Engineering at the University of Wollongong, Australia.