Development of a Long-term Accelerated Pavement Testing Programme and Structural Design Models

Transcription

1 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Development of a Long-term Accelerated Pavement Testing Programme and Structural Design Models Paper I-1 S V Kekwick, H L Theyse and E G Kleyn (presented by Dr M de Beer)

2 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Introduction HVS development since late 1960s; Three production machines operational from late 1970s to 1990s, plus prototype; Latest SA HVS commissioned 1999, with dynamic load simulation capability; Underpins SA pavement engineering efforts and developments - a significant track record;

3 MACRO-CLIMATE: SOUTH AFRICA & MAJOR ROAD SYSTEM Botswana DRY N1 North N1 N4 West Coast Namibië Capetown DRY N14 N7 N14 N10 DRY DRY N12 N10 N12 R12 N1 N9 MODERATE N2 N14 MODERATE N10 N14 DRY WET N11 N3 N1 MODERATE N12 N10 N1 N6 N2 N5 WET WET N2 N17 Durban East Coast

4 Surfacing Types of National Roads in South Africa (1997/8) PCC (7,5%) CRCP (0,5%) HMA (46,3%) Chip & Spray Seals (45,6%)

5 Base and Subbase Types of National Roads in South Africa (1997/8) G1/G2 Base on Stab Subbase (29%) G1/G2 Base on Nat gravel Subbase (27 %) 7% 6% 6% 3% 29% HMA (13 %) PCC (9 %) 9% HMA C3/C4 Base on Nat gravel Subbase (7 %) C3/C4 Base on Stab gravel Subbase (6%) 13% 27% G3/G4/G5 Base on Nat Gravel Subbase (6%) G3/ G4/ G5 o n Stab Subbase (3%)

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12 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE This paper... reviews factors that contributed to longterm success of SA HVS programme describes strategic and operational components of the programme discusses some specific examples of development of design transfer functions

13 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Objectives of the SA HVS programme Long-term: development of structural design models and transfer functions appropriate for local applications; Short-term: address specific pavement needs and problems as identified; Ultimate goal - to achieve optimal pavement design and most cost-effective structures

14 Before......after HVS

15 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Components of the SA HVS programme Steering Committee/Project Champions will define: Goals Specific tasks/purposes Policies Strategic plans Work programme/activities Operational statistics Deliverables/end products

16 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Components of the SA HVS programme Technology Transfer/Implementation Test level: interaction of champions and Steering Committee Test level: broader dissemination through presentations, workshops, site demonstrations Longer-term: development of generic design parameters, higher degree work Longer-term: inclusion in National guidelines

17 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Some significant SA APTrelated developments Mechanistic - Empirical analysis Damaging effect exponent quantification Dynamic Cone Penetrometer (DCP) design and analysis National guidelines/specifications Stress-In-Motion (SIM) technology Technology management Design transfer functions

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23 315/80 R22.5 HVS TIRE ON VRSPTA

24 Vertical Contact Stress: Variable loads: 315/80 R22.5 Tire

25 Lateral Contact Stress: Variable loads: 315/80 R22.5 Tire

26 Longitudinal Contact Stress: Variable Loads: 315/80 R22.5 Tire

27 Basic organizational process of converting needs to a products UNDERSTANDING QUALITY CONTROL PRODUCING Managerial guidelines, statistics, goals, purposes, policies, plans, programmes, deliverables PLANNING FINANCING DESIGN THE SOLUTION

28 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Process for partnered research and practice NEED NEED RESEARCH UNDER- STANDING PRACTICE PROCESSES DEFINED ENHANCED UNDERSTANDING & CAPABILITY PRODUCTS ENHANCED UNDERSTANDING & CAPABILITY

29 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Examples of structural pavement design models Transfer functions for: effective fatigue and crushing of lightly cemented layers permanent deformation of natural gravel base and subbase layers permanent deformation of imported (selected) and in situ subgrade layers

30 Fatigue Cracking and aging

31 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Number of load applications 1.00E+08 Fatigue 1.00E E E E E E E Strain Ratio / b A (95%) B (90%) C (80%) D (50%) Road Category (Expected Performance Reliability)

32 SURFACE DISINTEGRATION

33 1.00E E E E E E E E E+01 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Number of load applications Crushing 1.00E Stress Ratio v /UCS A (95%) B (90%) C (80%) D (50%) Road Category (Expected Performance Reliability)

34 RUTTING

35 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE VERTICAL STRESS (kpa) Permanent deformation G89TF50 0 1E+03 1E+04 1E+05 1E+06 1E+07 1E+08 NUMBER OF LOAD REPETITIONS Permanent Deformation 1 mm 2 mm 3 mm 5 mm 10 mm 20 mm

36 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Conclusions SA HVS programme has been the dominant force in SA pavement engineering development for more than 20 years significant advances in SA pavement engineering have arisen directly from the programme

37 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Conclusions Factors influencing the success of the SA HVS programme include: identification of longer-term goals from the outset interactive relationship between funders and research team mechanisms for technology transfer and information dissemination

38 ACCELERATED PAVEMENT TESTING 1999 INTERNATIONAL CONFERENCE Conclusions (continued) Factors (continued): developed understanding of the role of APT in pavement engineering formalisation of processes such as strategy development, progress monitoring, definition of deliverables appreciation of the need for higher-level analysis to attain long-term benefits up to four HVSs operating at the same time gave added impetus...