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Calibration of Mechanistic-Empirical Models for Cracking and Rutting of New Pavements Using Heavy Vehicle Simulator Tests
Dynatest International, Naverland 32, Glostrup, DK 2600, DENMARK, Email: pullidtz@dynatest.com
University of California, Davis, California, USA, Email: jtharvey@ucdavis.edu
California Department of Transportation, California, USA, Email: Khalid_Ghuslan@dot.ca.gov
University of California, Berkeley, California, USA, Email: bwtsai@berkeley.edu
University of California, Davis, California, USA, Email: bdsteven@ucdavis.edu
University of California, Berkeley, California, USA, Email: clm@newton.berkeley.edu
| Abstract /Introduction | HVS Tests | IRME |
| Unbound Layers |
| Summary of Results for All Calibration Sections | Conclusion | Acknowledgement & References |
Summary of Results for All Calibration Sections |
Figure 6 compares the measured and calculated ratios of final to initial deflection under a 40 kN wheel load for all of the HVS cracking tests. The deflections were measured by MDDs (at or close to the surface) and with the RSD. In general the response model did capture the increase in surface deflections quite well. The standard error of estimate is 0.61 mm.
The measured and calculated final permanent deformations of the asphalt layers are shown in Figure 7 for all of the test sections where it was recorded. The standard error of estimate for the permanent deformation of the asphalt was 1.76 mm. For the granular layers and for the subgrade the agreement between measured and calculated permanent deformation was equally good, but the final permanent deformations in those layers were much smaller, usually less than 3 mm.
Figure 6: Ratio of final to initial surface deflection for HVS cracking tests.
Figure 7: Final permanent deformation of AC layers.
The total permanent deformation at the pavement surface is shown in Figure 8. The standard error of estimate is 2.18 mm. Some of the outliers (two of the Goal 5 tests) were caused by insertion of water directly into the pavement (per the test plan).
Figure 8: Final permanent deformation at the pavement surface.
The number of loads to crack initiation was calculated or estimated for 17 HVS sections where data was available. The damage calculated by CalME for the top AC layer, at this number of loads, is shown in Figure 9, as a function of the total AC
thickness. The ATPB (Asphalt Treated Permeable Base) was included as an AC layer, where present. The signatures that are not filled in Figure 9 indicate drained sections with an ATPB layer.
Figure 9: Calculated damage at crack initiation.
The regression equation in Figure 9 is the best fitting linear relationship but for practical purposes (for example to avoid damage larger than 1) the S-shaped (sigmoidal) curve may be preferable. This has the equation:
Equation 10: S-shaped curve for damage at crack initiation as a function of AC thickness
| Where |
ωinitiation is the damage corresponding to crack initiation, and
hAC is the combined thickness of the asphalt layers. |
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