Heavy Duty Pavement Design

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Heavy duty pavements are pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities, such as container terminals and warehouses. Heavy duty pavement need to handle many types of freight handling vehicles, such as forklifts, straddle carriers, gantry cranes and side loaders. Heavy duty pavement often deals with slow moving or even static traffic load with ultra high load magnitude. Furthermore, the load wandering for heavy duty pavement such as contain port or warehouse is more significant than normal highway or urban road pavement. The goal of pavement design is to determine the number, material composition and thickness of the different layers within a pavement structure required to accommodate a given loading regime.

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  • Good afternoon, everyone. My name is Wei and I am an engineer from Pavement Management Services, New Zealand. Our company is a world leading technical consultant specialized in pavement management and transportation asset management. We provide a wide range of technical service to our clients including pavement condition testing, evaluation and design, highway asset inventory survey, pavement management system development and transportation asset management system development. Today, I will present you a short presentation on heavy duty pavement design. Hopefully, you can get some useful information from this.
  • Heavy Duty Pavement Design

    1. 1. Heavy Duty Pavement Design Dr Wei Liu Senior Engineer Fugro-PMS Ltd, New Zealand
    2. 2. Presentation Overview <ul><li>Introduction </li></ul><ul><li>Pavement Design Method for Heavy Duty Pavement </li></ul><ul><li>Case Study </li></ul>
    3. 3. Introduction <ul><li>Pavement is the layered structure on which vehicles will travel. It's purpose is two fold, to provide comfortable and durable surface for the vehicles and to reduce stresses to the underlying soils. </li></ul>
    4. 4. Introduction <ul><li>There are two types of pavement frequently in use throughout the world : </li></ul><ul><ul><li>Flexible - pavements with a bitumen bonded surface. </li></ul></ul><ul><ul><li>Rigid - Pavements with a concrete slab surface which can be un-reinforced, joint reinforced or continuously reinforced. </li></ul></ul>
    5. 5. Introduction <ul><li>What is Heavy Duty Pavements? </li></ul><ul><ul><li>Pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities, such as container terminals and warehouses </li></ul></ul>
    6. 6. Introduction <ul><li>Common pavement distresses: </li></ul><ul><ul><li>Rutting: a result of heavy, slow moving traffic. Common in warm areas. Permanent deformation in the wheel paths . </li></ul></ul><ul><ul><li>Fatigue Cracking: With every passing of a vehicle, pavement layer bends under loading. Over time, layer will crack; propagation of cracks upward eventually reaches the surface. Fatigue cracking occurs as individual cracks interconnect. </li></ul></ul>
    7. 7. Introdcution <ul><li>What is pavement design? </li></ul><ul><ul><li>The goal of pavement design is to determine the number, material composition and thickness of the different layers within a pavement structure required to accommodate a given loading regime. </li></ul></ul>
    8. 8. Introduction <ul><li>Special Issues in heavy duty pavement design </li></ul><ul><ul><li>Slow moving or static traffic load </li></ul></ul><ul><ul><li>Ultra high load magnitude </li></ul></ul><ul><ul><li>Load Wandering </li></ul></ul>
    9. 9. Heavy Duty Pavement Design Method <ul><li>Design Principle </li></ul><ul><li>Empirical Vs Mechanistic </li></ul><ul><li>Material Characterization </li></ul><ul><li>Load Characterization </li></ul><ul><li>Pavement Response Model </li></ul><ul><li>Failure Models </li></ul>
    10. 10. Heavy Duty Pavement Design Method <ul><li>Design Principle </li></ul><ul><ul><li>Minimize critical vertical stress in lower layers that result in </li></ul></ul><ul><ul><ul><li>Rutting </li></ul></ul></ul><ul><ul><li>Minimize critical tensile stresses in upper layers that result in </li></ul></ul><ul><ul><ul><li>Fatigue cracking </li></ul></ul></ul>
    11. 11. Heavy Duty Pavement Design Method <ul><li>Empirical Vs Mechanistic </li></ul><ul><ul><li>Empirical Methods are based on the results of experiments or experience. </li></ul></ul><ul><ul><ul><li>Advantage: Simpler approach </li></ul></ul></ul><ul><ul><ul><li>Disadvantage: Cannot cope with novel materials or pavement structures. </li></ul></ul></ul><ul><ul><ul><li> It is “like driving a car by only looking in the rear vision mirror, you could only be sure where you had been, but not where you were going” </li></ul></ul></ul><ul><li>– Geoff Youdale, Chairman, Austroads </li></ul><ul><li>Pavement Research Group </li></ul>
    12. 12. Heavy Duty Pavement Design Method <ul><li>Empirical Vs Mechanistic </li></ul><ul><ul><li>Mechanistic method applies the physics to determine: </li></ul></ul><ul><ul><ul><li>The reaction of structures to loading. </li></ul></ul></ul><ul><ul><ul><li>Distribution of vehicle loads to the underlying soil layers. </li></ul></ul></ul><ul><ul><ul><li>Need fundamental properties of the materials, pavement thicknesses, load characteristics. </li></ul></ul></ul>Traffic Climatic data Design & material property parameters Pavement response models (  ) Incremental fatigue damage models Transfer functions Performance prediction models (rutting, % cracks, etc….)
    13. 13. Heavy Duty Pavement Design Method <ul><li>Empirical Vs Mechanistic </li></ul><ul><ul><li>Advantages of mechanistic methods: </li></ul></ul><ul><ul><ul><li>Design for new load types (such as super single tires). </li></ul></ul></ul><ul><ul><ul><li>Design with new materials (such as Soilfix stabilized material). </li></ul></ul></ul><ul><ul><ul><li>Improve reliability of predicting performance. </li></ul></ul></ul><ul><ul><ul><li>Using performance related material properties. </li></ul></ul></ul><ul><ul><ul><li>Use of environmental effects. </li></ul></ul></ul>
    14. 14. Heavy Duty Pavement Design Method <ul><li>Material Characterization </li></ul><ul><ul><li>Subgrade </li></ul></ul><ul><ul><ul><li>Characterized by strength and/or stiffness </li></ul></ul></ul><ul><ul><ul><ul><li>California Bearing Ratio (CBR) </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Measures shearing resistance </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Units: percent </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Typical values: 0 to 20 </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Resilient Modulus (M R ) </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Measures stress-strain relationship </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Units: MPa </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Typical values: 30 to 300 MPa </li></ul></ul></ul></ul></ul>
    15. 15. Heavy Duty Pavement Design Method <ul><li>Material Characterization </li></ul><ul><ul><li>Subgrade </li></ul></ul><ul><ul><ul><li>Effect of Moisture Content </li></ul></ul></ul>
    16. 16. Heavy Duty Pavement Design Method <ul><li>Material Characterization </li></ul><ul><ul><li>Subbase and Roadbase </li></ul></ul><ul><ul><ul><li>Elastic Modulus E </li></ul></ul></ul><ul><ul><ul><li>Poisson’s Ratio </li></ul></ul></ul>Definitions of E and  .  D/2  l  l  l =  l / l  t =  D/D E =   =  l /  t
    17. 17. Heavy Duty Pavement Design Method <ul><li>Material Characterization </li></ul><ul><ul><li>Surface Layer </li></ul></ul><ul><ul><ul><li>Asphalt Mix </li></ul></ul></ul><ul><ul><ul><ul><li>Dynamic Modulus E* ( Witczak Equation) </li></ul></ul></ul></ul><ul><li>bitumen viscosity </li></ul><ul><li>loading frequency </li></ul><ul><li>air voids </li></ul><ul><li>effective bitumen content </li></ul><ul><li>cum. % retained on 19-mm sieve </li></ul><ul><li>cum. % retained on 9.5-mm sieve </li></ul><ul><li>cum. % retained on 4.76-mm sieve </li></ul><ul><li>% passing the 0.075-mm sieve </li></ul>
    18. 18. Heavy Duty Pavement Design Method <ul><li>Material Characterization </li></ul><ul><ul><li>Surface Layer </li></ul></ul><ul><ul><ul><li>Asphalt Mix </li></ul></ul></ul>
    19. 19. Heavy Duty Pavement Design Method <ul><li>Material Characterization </li></ul><ul><ul><li>Surface Layer </li></ul></ul><ul><ul><ul><li>Porland Cement Concrete </li></ul></ul></ul><ul><ul><ul><ul><li>Elastic Modulus </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Flexural strength </li></ul></ul></ul></ul>
    20. 20. Heavy Duty Pavement Design Method <ul><li>Load Characterization </li></ul><ul><ul><li>Pavement damage </li></ul></ul><ul><ul><ul><li>Miner’s law </li></ul></ul></ul><ul><ul><li>Characterization </li></ul></ul><ul><ul><ul><li>Spectrum </li></ul></ul></ul><ul><ul><ul><li>Expressed as a fraction of a standard load </li></ul></ul></ul><ul><ul><li>Pavement life </li></ul></ul><ul><ul><ul><li>Expression of how much load repetitions can be endured before unacceptable serviceability </li></ul></ul></ul>
    21. 21. Heavy Duty Pavement Design Method <ul><li>Pavement Response Model </li></ul><ul><ul><li>Layered Elastic Analysis </li></ul></ul><ul><ul><ul><li>Each layer is homogenous, isotropic, linearly elastic (E,  ) </li></ul></ul></ul><ul><ul><ul><li>Each layer is weightless </li></ul></ul></ul><ul><ul><ul><li>Infinite in x, y, finite in z direction </li></ul></ul></ul><ul><ul><ul><li>Uniform pressure applied over a circular area </li></ul></ul></ul><ul><ul><ul><li>Continuity at layer interfaces </li></ul></ul></ul><ul><ul><ul><ul><li>Same: vertical & shear stress </li></ul></ul></ul></ul><ul><ul><ul><ul><li> vertical and radial displacement </li></ul></ul></ul></ul>
    22. 22. Layer 1 HMA E 1 Layer 3 Subgrade Soil E 3 h 1 h 2 No bottom boundary, assume soil goes on infinitely. No horizontal boundary, assume layers extend infinitely. Tire has a total load P, spread over a circular area with a radius of a, resulting in a contact pressure of p. Pavement Reactions Deflection (  ) Tensile Strain (  t ) Compressive Strain (  v ) Layered Elastic Model Representation of a Pavement Layer 2 Granular Base E 2
    23. 23. Heavy Duty Pavement Design Method <ul><li>Pavement Response Model </li></ul><ul><ul><li>Critical Pavement Responses and Locations </li></ul></ul>Vertical compressive strain Top of subgrade Vertical compressive strain Top of intermediate layer (base or subbase) Horizontal tensile strain Bottom of HMA layer(s) Deflection (vertical) Pavement surface Response Location
    24. 24. Heavy Duty Pavement Design Method <ul><li>Failure Models </li></ul><ul><ul><li>Fatigue Cracking </li></ul></ul><ul><ul><ul><li>allowable number of load repetitions related to tensile strain at bottom of asphalt layer </li></ul></ul></ul><ul><ul><ul><li>AI & Shell design methods -- allowable load repetitions related to tensile strain and modulus </li></ul></ul></ul><ul><ul><ul><ul><ul><li>N f = f 1 (  t ) -f2 (E 1 ) -f3 </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Modulus effect is small (f3 is smaller than f2) </li></ul></ul></ul><ul><ul><ul><li>Several models that include only strain : N f = f 1 (  t ) -f2 </li></ul></ul></ul>
    25. 25. Heavy Duty Pavement Design Method <ul><li>Failure Models </li></ul><ul><ul><li>Rutting </li></ul></ul><ul><ul><ul><li>2 procedures to limit rutting </li></ul></ul></ul><ul><ul><ul><ul><li>limit vertical compressive strain on top of subgrade </li></ul></ul></ul></ul><ul><ul><ul><ul><li>limit total accumulated permanent deformation </li></ul></ul></ul></ul><ul><ul><ul><li>AI and Shell design -- allowable number of load repetitions to limit rutting related to vertical compressive strain on top of subgrade </li></ul></ul></ul><ul><ul><ul><li>Form (can be used for all materials): </li></ul></ul></ul><ul><ul><ul><ul><ul><li> p = a(  ) b (N) 1-m </li></ul></ul></ul></ul></ul>
    26. 26. Heavy Duty Pavement Design Method <ul><li>Failure Models </li></ul><ul><ul><li>Miner’s Hypothesis </li></ul></ul><ul><ul><ul><li>Provides the ability to sum damage for a specific distress type </li></ul></ul></ul><ul><ul><ul><li>D =  n i /N i  1.0 </li></ul></ul></ul><ul><ul><ul><li>where n i = actual number of repetitions for load i </li></ul></ul></ul><ul><ul><ul><li> N i = allowable number of repetitions for load i </li></ul></ul></ul>
    27. 27. Case Study <ul><li>Design Conditions: </li></ul><ul><ul><li>A concrete pavement for a heavy duty industrial hardstand with a total repetition of 182,5000 with a 10 ton axle load for a period of 5 years. </li></ul></ul><ul><ul><li>Roadbase is the Soilfix Stabilized Aggregate </li></ul></ul>
    28. 28. Case Study <ul><li>Design Inputs: </li></ul>0.4 Compact Soil 3 0.2 6890 300 Soilfix Stabilized Aggrage 2 0.15 3000 200 Porland Cement Concrete 1 Poisson’s Ratio Modulus (MPa) Thickness (mm) Material Layer
    29. 29. Case Study <ul><li>Pavement Response Calculations </li></ul><ul><ul><li>Critical Stresses in Pavement Structure </li></ul></ul>0 0 0 38.49 36.62 36.51 500 0 171.5 3 4 0 0 0 37.04 35.28 35.1 500 0 0 3 3 0 0 0 407 -2660.59 -2207.53 200 0 171.5 1 2 0 0 0 350.19 -2461.34 -1970.76 200 0 0 1 1 XY XZ YZ Z Y X Z Y X Shear Stress (kPa) Normal Stress (kPa) Coordinates (mm) Layer Loc#
    30. 30. Case Study <ul><li>Pavement Response Calculations </li></ul><ul><ul><li>Critical Strains and Displacements in Pavement Structure </li></ul></ul>1072.66 0 0 93.01 47.91 45.1 500 0 171.5 3 4 1059.58 0 -7.59 89.52 46.84 42.68 500 0 0 3 3 1081.58 0 0 56.86 -119.53 -93.47 200 0 171.5 1 2 1067.43 0 15.3 50.75 -110.91 -82.7 200 0 0 1 1 Z Y X Z Y X Z Y X Displacement (micrometer) Normal MicroStrain Coordinates (mm) Layer Loc
    31. 31. Case Study <ul><li>Pavement Life Prediction </li></ul><ul><ul><li>Fatigue Cracking Model </li></ul></ul><ul><ul><li>Rutting Model </li></ul></ul><ul><ul><li>Results: </li></ul></ul>0.01 0.12 Damage Factor 2.41E+08 1.54E+07 Allowed Numbers 1825000 1825000 Applied Numbers Rutting Fatigue  
    32. 32. Thank you!

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