Dynamic Time Domain Backcalculation of Layer Moduli,Damping,and Thicknesses in Flexible Pavements

Abstract

A dynamic time domain method was developed to backcalculate the layer moduli, damping ratios, and thicknesses of asphalt pavements from dynamic falling weight deflectometer test data. The method uses the SAPSI program as a forward routine and a Newton-Raphson method for the backcalculation. The advantage of the time domain approach is that SAPSI can match selected features of the measured time histories directly, and inaccurate measurements at the ends of histories can be ignored. The peak deflections and the time lag between the peak of the load and the peak of the deflections at different sensors are matched. The Newton algorithm in MICHBACK is adopted to perform the backcalculation. The new algorithm is capable of backcalculating the moduli, damping ratios, and thicknesses of three-layer flexible pavements reasonably well. Backcalculations based on synthetic time histories generated using SAPSI show excellent stability and accuracy. Backcalculation using measured time histories yields less accurate results. Possible sources for the discrepancies when using field data are addressed.

Get full access to this article

View all access options for this article.

References

Kang

Y. V.

Multifrequency Backcalculation of Pavement-Layer Moduli. ASCE Journal of Transportation Engineering, Vol. 124, No. 1, 1998, pp. 73–81.

Magnuson

A. H.

, Lytton

R. L.

, and Briggs

R. C.

. Comparison of Computer Predictions and Field Data for Dynamic Analysis of Falling- Weight Deflectometer Data. In Transportation Research Record 1293, TRB, National Research Council, Washington, D.C., 1991, pp. 61–71.

Chatti

, Haider

W. S.

, Lee

H. S.

, Ji

Y. G.

, and Salama

. Evaluation of Nonlinear and Dynamic Effects on Pavement Response Under FWD Loading. International Journal of Pavements, Vol. 2, 2003, pp. 88–99.

Al-Khoury

, Scarpas

, Kasbergen

, and Blaauwendraad

. Spectral Element Technique for Efficient Parameter Identification of Layered Media. Part I: Forward Calculation. International Journal of Solids and Structures, Vol. 38, 2001, pp. 1605–1623.

Al-Khoury

, Scarpas

, Kasbergen

, and Blaauwendraad

. Spectral Element Technique for Efficient Parameter Identification of Layered Media. Part II: Inverse Calculation. International Journal of Solids and Structures, Vol. 38, 2001, pp. 8753–8772.

Uzan

Dynamic Linear Backcalculation of Pavement Material Parameters. ASCE Journal of Transportation Engineering, Vol. 120, No. 1, 1994, pp. 109–126.

Uzan

Advanced Backcalculation Techniques. In Nondestructive Testing of Pavements and Backcalculation of Moduli, Vol. 2 ( Von Quintus

H. L.

et al., eds.), ASTM STP 1198, Philadelphia, Pa., 1994, pp. 3–37.

Ong

C. L.

, Newcomb

D. E.

, and Siddharthan

. Comparison of Dynamic and Static Backcalculation Moduli for Three-Layer Pavements. In Transportation Research Record 1293, TRB, National Research Council, Washington, D.C., 1991, pp. 86–92.

Chen

S. S.

The Response of Multilayered Systems to Dynamic Surface Loads. Ph.D. dissertation. University of California-Berkeley, 1987.

10.

Harichandran

R. S.

, Mahmood

, Raab

A. R.

, and Baladi

G. Y.

. Modified Newton Algorithm for Backcalculation of Pavement Layer Properties. In Transportation Research Record 1384, TRB, National Research Council, Washington, D.C., 1993, pp. 15–22.

11.

Khazanovich

Dynamic Analysis of FWD Test Results for Rigid Pavements. In Nondestructive Testing of Pavements and Backcalculation of Moduli, Vol. 3, ASTM STP 1375 ( Tayabji

S. D.

and Lukanen

E. O.

, eds.), West Conshohocken, Pa., 2000, pp. 383–397.

12.

Losa

The Influence of Asphalt Pavement Layer Properties on Vibration Transmission. International Journal of Pavements, Vol. 1, No. 1, 2002, pp. 67–76.

13.

Chatti

, Haider

S. W.

, Lee

H. S.

, Ji

, and Salama

. Evaluation of Nonlinear and Dynamic Effects on Asphalt Pavement Response Under FWD Loading. International Journal of Pavements, Vol. 2, No. 1-2, 2003, pp. 88–99.

14.

Tajirian

F. T.

Impedance Matrices and Interpolation Techniques for 3-D Interaction Analysis by the Flexible Volume Method. Ph.D. dissertation. University of California, Berkeley, 1981.