1 / 24

Pavement Design Task Group Feedback

Pavement Design Task Group Feedback. RPF meeting 23 November 2005. Sequence of events. RPF May 2005 Establish task group 1 st Meeting Discussion of role and operation of the task group Presentation on potential improvements to mechanistic-empirical (ME) design method

ifeoma-waters
Download Presentation

Pavement Design Task Group Feedback

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pavement Design Task Group Feedback RPF meeting 23 November 2005

  2. Sequence of events • RPF May 2005 • Establish task group • 1st Meeting • Discussion of role and operation of the task group • Presentation on potential improvements to mechanistic-empirical (ME) design method • Unpacking of ME design method core • 2nd Meeting • Presentation on a project performance based design method • Presentation of simulation models • Discussion of the deliverable from the process Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  3. Sequence of events • 3rd Meeting • Integration of the performance based information system and the ME-design component into a single design method • Design sensitivity analysis based on the current ME design method • Details of the performance based information system • 4th Meeting • Unpacking the details of the ME-design component • Development of a R&D matrix and rating of the R&D areas Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  4. Prof M de Beer (CSIR); Prof E Horak (UP); Mr M Henderson (PAWC); Prof K Jenkins (US); Dr F Jooste (MAS); Dr G Jordaan (Tshepega); Mr L Kannemeyer (SANRAL); Dr F M Long (MAS); Mr P Olivier (J&G); Mr B Perrie (C&CI); Mrs E Sadzik (Gautrans); Mr A Taute (Vela VKE); Mr H L Theyse (CSIR); Dr I van Wijk (Africon); and Dr H Wolff (Nyeleti). Task group members

  5. General recommendations:Deliverable from the task group • The task group will deliver a research and development (R&D) plan that will guide the development of a pavement design method for southern Africa that • allows for a range of design applications of different importance and • caters for a user group with different levels of design experience • R&D plan to be executed under the auspices of the Road Pavement Research Advisory Committee (RPRAC) • Project management may be referred back to sub-groups of the task group Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  6. General recommendations • The R&D plan is aimed at developing an improved design method based on • A performance based information system • Mechanistic-empirical design concepts • Initial intention to include rigid and block pavement design • Details of design sufficiently different to treat separately • Urgent need to develop single design guide for all types of pavements Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  7. General recommendations • The R&D plan only covers R&D activities to develop improved design method • Dissemination of individual research results and design method as a whole • Not descriptive in terms of delivery mechanisms such as software packages • RPRAC may considered the development of a software package as a form of delivery mechanism • The improved design method should close the gap between ME-design and day-to-day engineering as far as possible • Conventional ME-design focus almost exclusively on the effect of the imposed stresses • Recent research on unbound material shows the effect of field variables such as density and saturation is equally important • The improved design method must incorporate the effect of field variables Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  8. General recommendations • Initially a separate task group for design traffic • Design traffic estimation is an integral part of pavement design • Design traffic task group combined with pavement design task group • The improved design method should allow for gradual transition from the E80 concept to mixed traffic design • Revision of guideline documents containing sound engineering practice excluded form the R&D plan • Close integration required between guidelines and the design method Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  9. Integration of guidelines and design method

  10. Performance based information system • Based on performance data collected from • Rehabilitation investigation documentation • APT test results • Statement of fact rather than interpretation of data and modelling Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  11. Integration of performance based and ME-design components Design Method ME-design component Entry level Performance based information system • Design scenario: • Routine design • Low design experience • Use only known materials • Conventional material classification Intermediate level • Design scenario: • Important design • Seasoned professional designer • Test input parameters for materials • Design scenario: • Very important design • Special investigations • Specialist designer • Unusual materials • Test input and performance of materials Advanced level

  12. Design Option Performance Database • 8 Years to Resurface • 1278 H/day • 8 MESA to Rehab • Terminal Rut = 16 mm Click here for Design Report Click here for Situation Summary Click here for Rehab. Report • Not Resurfaced • 987 H/day • 5 MESA to Rehab • Terminal Rut = 12 mm Click here for Design Report Click here… • 11 Years to Resurface • 1250 H/day • 9 MESA to Rehab • Terminal Rut = 14 mm Click here for Design Report Click here… • 10 Years to Resurface • 1400 H/day • 12 MESA to Rehab • Terminal Rut = 17 mm Click here for Design Report Click here… Performance based information system

  13. Mechanistic-empirical design component • Basic ME procedure • Fully determines the accuracy of the ME-design component • Requires engineering knowledge and understanding • Various implementation schemes • Allows for spatial and time-based variation • Enhances the interpretation of results • Requires mathematical and computer programming skills Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  14. Input layers Future Current Geometry Computer solution Traffic data Axle load histogram Fixed load Damage models Contact stress histogram Fixed contact stress Thermal cracking Resilient response models Resilient response analysis Structural capacity estimate Fatigue HMA Grading Mr = Constant Plastic strain/ permanent deformation Binder content Other? Binder properties Mr = f (Temp) HMA Plastic strain/ permanent deformation Unbound Temperature Other? Other? Mr = f (Dens, saturation) Crushing Grading Stiffness reduction Stabilized Mr = f (Bulk and shear stress) Atterberg limits Plastic strain/ permanent deformation Material data Other? Moisture content Unbound Mr = f (Strain) Density Plastic strain/ permanent deformation Subgrade Other? Other? Linear visco-elastic UCS Stress and strain at break Stabilized Other? Time/previous loading Other?

  15. Pre-processing Post-processing Traffic loading Frequency Extent of fatigue Frequency Frequency Basic me-design module Time Fatigue life Axle load Contact stress Frequency Rut Terminal rut Spatial variation of field variables Layer thickness Temperature Binder content Relative density Saturation Grading etc. Time Rut life T1 T2 T3 Tn RD3, S3 RD1, S1 RD2, S2 RDn, Sn Frequency Riding quality s2b, e2b s3b, e3b s1b, e1b snb, enb Unacceptable Time Riding quality life

  16. Research & Development Plan • Main components of the R&D plan • Integration level project • Performance based information system • Demand analysis • Traffic and natural environment • Material response models • Pavement response models • Damage models • Probabilistic and recursive implementation schemes • R&D needs formulated for each component • Short, medium and long-term actions formulated for each R&D need • Each action rated in term of benefit/impact and effort/cost Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  17. Execution of R&D plan:Integration of activities

  18. Execution of R&D plan:Stress effect theme

  19. Execution of R&D plan:Field variable effect theme

  20. Rating of short-term R&D objectives • Integration level project • Integrate output from R&D projects into single design method • Reality checks and validation • Develop manual on use of method Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  21. Rating of short-term R&D objectives (continued) • Material response models • Agreement between different deflection methods Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  22. Rating of short-term R&D objectives Summary • Integration project and performance based information system • Average benefit ratings between 3,8 and 3,9 • Average benefit/effort between 114 and 190 % • Demand analysis • 3 out of 6 items had average benefit ratings between 3,5 and 3,9 the other items were between 2,8 and 3,2 • Average benefit/effort between 96 and 159 % • Material resilient response models • Average benefit ratings between 3,6 and 4,1 • Average benefit/effort between 99 and 141 % Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  23. Rating of short-term R&D objectives Summary • Pavement resilient response models • Average benefit ratings between 2,4 and 3,4 • Average benefit/effort between 70 and 98 % • Damage models • Average benefit ratings between 3,6 and 4,4 • Average benefit/effort between 112 and 146 % • Probabilistic and recursive implementation schemes • Average benefit ratings between 3,5 and 3,9 • Average benefit/effort between 132 and 152 % Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990)

  24. Recommendation to RPRAC • Select projects based on • Ratings • Recent and ongoing research that may fast-track certain projects • The achievement of the objective of the R&D plan to developed an improved design method for flexible pavements

More Related