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Railway Geotechnics covers track, track substructure, load environment, materials, mechanics, design, construction, measurements, and management. Illustrated by case studies, with an emphasis on the geotechnical aspects of railway engineering, it discusses these topics from a historical perspective. It also presents the methodologies and best practices developed over the past 20 years.
Features
• Offers methods, best practices and case studies
• Illustrates with examples of "how to do it"
• Includes descriptions of the latest technologies and development related to track substructure
Summary
Links Geotechnics with Railway Track Engineering and Railway Operation
Good railway track and railway operations depend on good geotechnics, in several different ways and at varying levels.
Railway Geotechnics covers track, track substructure, load environment, materials, mechanics, design, construction, measurements, and management. Illustrated by case studies, with an emphasis on the geotechnical aspects of railway engineering, it discusses these topics from a historical perspective. It also presents the methodologies and best practices developed over the past 20 years.
Written by Four Experienced Professionals
This book:
• Emphasizes the practical aspects and best practices for railway track and substructure
• Contains guidelines for design, construction, and maintenance of railway track and substructure
• Provides many examples and case studies
Railway Geotechnics is written primarily for professionals and graduate students, and begins with the fundamentals and basic principles, leading in to practical applications. The authors bring considerable experience and expertise, with many years of research and development, academia, railway operations, and consulting.
Table of Contents
1 Track
1.1 Introduction
1.2 Historical perspective
1.2.1 US railway expansion
1.2.2 Development of modern mainline track substructure
1.2.3 Future for track substructure
1.3 Superstructure
1.4 Substructure
1.4.1 Ballast
1.4.2 Subballast
1.4.3 Subgrade (trackbed, formation)
1.4.4 Slopes
1.5 Substructure effects on track performance
1.6 Alternative track structures
1.7 Track transitions
1.7.1 Bridge approach
1.7.2 Ballasted track to slab track
1.7.3 Special trackwork
1.7.4 Grade crossing
1.8 Track inspection and maintenance
1.8.1 Inspection
1.8.2 Maintenance
1.8.3 Management
1.9 Layout of the book
2 Loading
2.1 Static loading
2.2 Cyclic loading
2.3 Dynamic loading
2.3.1 Dynamic load or impact load factor
2.3.2 High-frequency forces
2.3.3 General equations for calculating dynamic wheel–rail forces
2.3.4 Modeling for dynamic wheel–rail forces
2.3.5 Stiffness and damping parameters in track modeling
2.3.6 Dynamic track modeling results
2.3.7 Measured dynamic wheel–rail forces
2.3.8 Critical speed of high-speed passenger trains
2.4 Load transfer in track foundation
2.4.1 Stresses and strains in track foundation
2.4.2 Load transmission in track
2.4.3 Strength properties
2.4.4 Total stress, effective stress, and pore water pressure
2.5 Moving load and principal stress rotation
3 Substructure
3.1 Ballast
3.1.1 Ballast functions
3.1.2 Parent rock characterization
3.1.3 Aggregate characterization
3.1.3.1 Grain size distribution
3.1.3.2 Shape, angularity, texture
3.1.3.3 Petrographic analysis
3.1.3.4 Crushing and abrasion resistance
3.1.3.5 Bulk-specific gravity, absorption, sulfate soundness
3.1.3.6 Ballast aggregate specifications
3.1.4 Ballast fouling
3.1.5 Ballast layer behavior
3.1.5.1 Ballast layer strength parameters
3.1.5.2 Ballast stress–strain behavior
3.1.5.3 Ballast deformation
3.1.5.4 Ballast layer residual stress
3.1.5.5 Ballast strength and deformation tests
3.1.6 Ballast compaction
3.1.7 Used ballast
3.2 Subballast
3.2.1 Subballast functions
3.2.2 Subballast characterization
3.2.3 Subballast performance
3.2.4 Subballast drainage
3.2.5 Separation
3.3 Subgrade
3.3.1 Subgrade functions
3.3.2 Soil types
3.3.3 Common problems
3.3.4 Subgrade improvement methods
3.4 Other substructure materials
3.4.1 Ballast treatment methods
3.4.2 Alternative subballast materials
3.4.3 Hot mix asphalt
3.4.4 Concrete and cementitious material
3.4.5 Water
3.5 Track transitions
4 Mechanics
4.1 Track and subgrade models
4.1.1 BOEF model
4.1.2 Track modulus
4.1.3 Half-space model
4.1.4 GEOTRACK
4.1.5 Track modulus analysis using GEOTRACK
4.1.6 Track modulus as a measure of track support
4.1.7 KENTRACK
4.1.8 Finite element model
4.2 Resilient modulus
4.2.1 Resilient modulus of granular materials
4.2.2 Resilient modulus of fine- grained subgrade soils
4.2.3 Influence of soil physical state on resilient modulus
4.2.4 Li–Selig method for prediction of resilient modulus
4.2.5 Examples of prediction using Li–Selig method
4.3 Cumulative plastic deformation
4.3.1 Cumulative plastic deformation of ballast
4.3.2 Cumulative plastic deformation of subballast
4.3.3 Cumulative plastic deformation for fine-grained soils
4.3.3.1 Soil critical state
4.3.3.2 Prediction model
4.3.3.3 Li–Selig model for cumulative plastic deformation
4.3.4 Effects of traffic, ballast, and subgrade conditions on total settlement
4.3.5 Track settlement and roughness
4.3.6 Track settlement at bridge approaches
4.3.6.1 Ballast layer deformation
4.3.6.2 Subgrade layer deformation
4.3.6.3 Field investigation and modeling results
5 Design
5.1 Ballasted track
5.1.1 Background
5.1.2 Design methods for granular layer thickness
5.1.2.1 AREMA equations
5.1.2.2 Raymond method
5.1.2.3 British Rail method
5.1.2.4 Li–Selig method
5.1.3 Development of Li–Selig method
5.1.3.1 Subgrade failure criteria
5.1.3.2 Effect of granular layer on subgrade stress
5.1.3.3 Design chart development
5.1.4 Application of Li–Selig method
5.1.4.1 Design traffic
5.1.4.2 Material properties
5.1.4.3 Design criteria
5.1.4.4 Design procedure 1
5.1.5 Comparisons with test results
5.1.5.1 Low track modulus test track
5.1.5.2 Mix passenger and freight revenue service sites
5.1.6 Initial granular layer construction thickness
5.2 Asphalt track
5.2.1 Asphalt track foundation
5.2.2 Asphalt mix design
5.2.3 Asphalt track foundation design
5.2.4 Use of asphalt track for drainage
5.2.5 Asphalt track foundation test under heavy axle loads
5.3 Slab track foundation
5.3.1 Overall requirements
5.3.2 Failure modes and design criteria
5.3.3 Design of concrete slab
5.3.4 Subgrade and subbase
5.3.5 Analysis of slab track foundation
5.3.6 Slab track design based on subgrade deformation
5.4 Track transition
5.4.1 Design principles/best practices
5.4.1.1 Bridge approach
5.4.1.2 Slab track to ballasted track
5.4.1.3 Special trackwork
5.4.1.4 Grade crossing
5.4.2 Examples of design and remediation
5.4.2.1 Reduce stiffness and increase damping for track on bridge
5.4.2.2 Consistent track strength/restraint
5.4.2.3 Soil improvement
5.4.2.4 Unnecessary stiffness transition from slab track to ballasted track
6 Drainage
6.1 Sources of water in the track
6.1.1 Direct water
6.1.2 Runoff water
6.1.3 Ground water
6.1.4 Capillary action of water in soil
6.1.5 Longitudinal flow of water in track
6.2 Water effects on track substructure
6.2.1 Granular soil
6.2.2 Cohesive soil
6.2.3 Internal erosion/piping
6.2.4 Erosion from surface water
6.2.5 Frost heave
6.3 Water principles for track
6.3.1 Water flow through soil
6.3.2 Surface water flow
6.4 Drainage materials
6.4.1 Pipes
6.4.2 Graded aggregate
6.4.3 Geosynthetics
6.4.3.1 Geotextiles
6.4.3.2 Geomembranes
6.4.3.3 Geocomposites
6.4.4 Hot mix asphalt
6.5 External track drainage design
6.5.1 Diverting water away from track
6.5.2 Right-of-way mapping
6.5.3 Ditch and slope
6.6 Internal track drainage design
6.6.1 Internal drainage flow nets
6.6.2 Ballast and subballast layers
6.6.3 Design approach
6.6.4 Ballast pockets
6.7 Drainage improvement and rehabilitation
6.7.1 Ballast cleaning
6.7.2 Subballast drainage
6.7.3 Ditching and grading
7 Slopes
7.1 New slopes
7.1.1 Site characterization
7.1.2 Materials
7.1.3 Embankment fills
7.1.3.1 Foundation
7.1.3.2 Embankment
7.1.3.3 Steepened slopes
7.1.3.4 Retaining structures
7.1.4 Cut slopes
7.2 Existing soil slopes
7.2.1 Types of instability
7.2.2 Field investigation
7.2.2.1 Site reconnaissance
7.2.2.2 Test borings
7.2.2.3 Geotechnical instrumentation
7.2.3 Examples of railway embankment instability
7.3 Soil slope stability analysis
7.3.1 Basic method of slices
7.3.2 Example of method of slices
7.3.3 Factor of safety
7.3.4 Computer models
7.3.5 Soil strength and stress condition
7.3.6 Effects of train load
7.4 Rock slopes
7.4.1 Types of instability
7.4.2 Investigation
7.4.3 Basic mechanics of rock slope stability
7.4.4 Rock slope stability analysis
7.5 Slope monitoring and stabilization
7.5.1 Monitoring
7.5.2 Slope stabilization
7.5.2.1 Drainage
7.5.2.2 Structural restraint
7.5.2.3 Buttress restraint
7.5.2.4 Soil improvement
7.5.2.5 Rock slope considerations
8 Measurements
8.1 Site investigations and characterization of track substructure conditions
8.1.1 Desk study
8.1.2 Field reconnaissance
8.1.2.1 Soil types and strata
8.1.2.2 Ground and surface water
8.1.2.3 Soil strength and stiffness properties
8.1.3 Mapping
8.1.3.1 Ground-based LIDAR systems
8.1.4 Cross-trenches
8.1.5 Test borings
8.1.6 In situ tests
8.2 Ground penetrating radar
8.2.1 GPR fundamentals
8.2.2 GPR for track surveys
8.2.3 Equipment 377
8.2.4 Example GPR image results
8.2.5 Track substructure condition measurements
8.2.5.1 GPR measurement of fouled ballast
8.2.5.2 GPR measurement of moisture
8.2.5.3 GPR measurement of layers
8.3 Track geometry
8.3.1 Measurement fundamentals
8.3.3 Measures of geometry variation
8.3.3.1 Spatial correction to “line up” successive geometry data
8.3.3.2 Standard deviation over fixed segment track length
8.3.3.3 Running roughness
8.3.3.4 Other measures of track roughness
8.3.4 Track alignment control for high-speed rail
8.3.5 Advances in analysis of track geometry data
8.3.5.1 Analyzing track geometry space curve data
8.3.6 Filtered space curve cyclic characteristics and vehicle dynamics
8.3.7 Determining effectiveness of geometry correction from waveform analysis
8.3.8 Performance-based track geometry inspection
8.3.8.1 Objectives and background
8.3.8.2 Vehicle performance measures
8.3.8.3 Types of performance-based track geometry inspection systems
8.3.8.4 Performance criteria
8.4 Track deflection under load
8.4.1 Track stiffness/deflection measurement techniques
8.4.1.1 Track stiffness testing using track loading vehicle
8.4.1.2 University of Nebraska track deflection measurement
8.4.1.3 Rolling stiffness measurement vehicle—Banverket
8.4.1.4 Falling weight deflectometer
8.4.1.5 Spectral analysis of surface waves
8.4.2 Vertical load-deflection behavior
8.4.3 Lateral load-deflection behavior
8.4.4 Track buckling and track panel shift
9 Management
9.1 Life-cycle cost considerations
9.1.1 Designing track to minimize settlement versus allowing settlement and geometry corrections
9.1.2 Track renewal with reconstruction versus limited renewal of track components
9.1.2.1 Track laying machines and track subgrade renewal machines
9.1.3 Cost considerations of ballast-less track (slab track)
9.1.3.1 Top-down versus bottom-up slab track construction
9.1.4 Vertical rail deflection to locate soft track support of new track
9.2 Ballast life
9.2.1 Influence of ballast depth on ballast life
9.2.2 Influence of tamping degradation on ballast life
9.3 Maintenance needs assessment
9.3.1 Functional condition
9.3.2 Structural condition
9.3.3 Vertical rail deflection to locate soft support of existing track
9.3.4 Assessment of track life and maintenance needs
9.4 Maintenance methods and equipment
9.4.1 Tamping
9.4.2 Improved methods to correct track geometry error
9.4.2.1 Design over-lift tamping
9.4.2.2 Improved tamper control systems
9.4.2.3 Stone blowing
9.4.3 Ballast shoulder cleaning
9.4.4 Ditching
9.4.5 Ballast undercutting/cleaning
9.4.6 Track vacuum
9.5 Examples of management based on measurement
9.5.1 Using track geometry data to determine tamping needs
9.5.2 Poor ride quality: Due to track geometry error or the vehicle?
9.5.3 Managing the dip at track transitions
9.5.4 Managing undercutting: Selecting locations, track segment length, and their priority
9.6 Subballast and subgrade improvement and rehabilitation
9.6.1 Subballast improvement methods
9.6.2 Subgrade stabilization methods
9.6.2.1 Over-excavation and replacement
9.6.2.2 Admixture stabilization
9.6.2.3 Horizontal reinforcement
9.6.2.4 Rammed-aggregate piers
9.6.2.5 Compaction grouting
9.6.2.6 Penetration grouting
9.6.2.7 Soil mixing
9.6.2.8 Slurry injection
9.6.3 Control of expansive soil
9.7 Observational method
9.7.1 Examples of use
9.7.2 Potential disadvantages of the observational method
10 Case studies
10.1 Diagnosis and remediation of a chronic subgrade problem
10.1.1 Background and investigation (diagnosis)
10.1.2 Substructure conditions
10.1.3 Solution and implementation
10.1.4 Monitoring
10.2 Track design on old roadbed
10.2.1 Investigation
10.2.1.1 Use of GPR to assess old roadbed conditions
10.2.1.2 Use of track geometry car data
10.2.1.3 Use of mapping 493
10.2.2 Granular layer thickness design
10.2.2.1 Design method 1
10.2.2.2 Design method 2
10.2.3 Challenges encountered during design
10.2.3.1 Unstable slopes
10.2.3.2 Poor internal and external track drainage
10.3 Track design—new roadbed
10.3.1 Background
10.3.2 Site description and soil conditions
10.3.3 Track foundation design
10.3.4 Construction control
10.4 Slope instability
10.4.1 Investigation
10.4.2 Site conditions
10.4.3 Potential solutions
10.4.3.1 Flattening/buttressing
10.4.3.2 Retaining wall with anchored tie backs
10.4.3.3 Soil reinforcement
10.4.3.4 Micropiles with cap beam
10.4.3.5 Anchored blocks
10.4.3.6 Soil dowels
10.4.4 Extent of remediation
Appendix
References
Index
