Calibration of Reflection Cracking and Permanent Deformation Models for Overlays Using Heavy Vehicle Simulator Tests
Dynatest International, Naverland 32, Clostrup, DK 2600, DENMARK, Email: pullidtz@dynatest.com
University of California, Davis, California, USA, Email: jtharvey@ucdavis.edu
University of California, Davis, California, USA, Email: rzwu@ucdavis.edu
University of California, Davis, California, USA, Email: djjones@ucdavis.edu
University of California, Berkeley, California, USA, Email: clm@newton.berkeley.edu
| Abstract | Introduction | Simulation of HVS Tests using CalME | Reflection Cracking Model |
| Simulation of Pavement Response | Permanent Deformation | Cracking | Conclusion | Acknowledgement & References |
Permanent Deformation |
Permanent deformations were measured both during the rutting experiment and during the reflection cracking experiment. The permanent deformation in the asphalt layers was calculated from:
Equation 4: Permanent deformation (down rut) of asphalt
| Where |
K is a calibration factor determined from HVS testing,
hi is the thickness of layer i, and
γii is the inelastic (permanent) shear strain in layer i, determined from: |
Equation 5: Gamma function for inelastic shear strain.
| Where |
γe is the elastic (resilient) shear strain,
τ is the shear stress,
N is the number of load repetitions,
τref is a reference shear stress (0.1 MPa), and
A, α, β, and γ are constants determined from the RSST-CH. |
The summation in Equation 4 is done for the top 100 mm of the asphalt. Permanent deformation due to post compaction was not calculated. Permanent deformations of
the unbound layers were calculated using the model given in Ullidtz, et al. (2008a). They were quite small for all tests.
The same calibration factor (K = 1.4) was used for all of the tests, even though the rutting experiment was done using uni-directional loading and the reflection cracking experiment was with bi-directional loading.
Figure 3: Measured and calculated down rut during rutting study
Figure 4: Measured and calculated down rut during reflection cracking study.
The measured and the simulated down rut during the rutting study are shown in Figure 3. For all of the tests the calculated down rut is 6% lower than the measured values, with an R2 of 0.86 and a standard error of estimate of 1.3 mm. For the
reflection cracking study (Figure 4) the calculated down rut is 19% below the measured values, the R2 is 0.83 and the standard error of estimate is 0.9 mm.
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