00627250

Component

http://onlinepubs.trb.org...trr/1992/1377/1377-019.pdf

https://scholar.google.co...rian&publication_year=1992

The spectral analysis of surface waves (SASW) method has been used as a nondestructive test method for determining elastic modulus profiles of pavement systems. To perform the test, a disturbance is applied to the pavement surface to generate stress waves that propagate mostly as surface waves of various wavelengths. The waves are monitored and captured with a data acquisition system. Signal and spectral analyses are used to determine a dispersion curve (variation in phase velocity with wavelength). The last step is to determine the elastic modulus of various layers from the dispersion curve. Several alternatives are available. First, a trial-and-error (forward modeling) process can be carried out. Second, optimization techniques can be used. Finally, generalized inverse theory can be implemented. In most applications, the backcalculation of layer moduli is accomplished using a manual trial-and-error matching process between the theoretical and experimental dispersion curves. Unfortunately, this process is rather time consuming and requires engineering judgment. To improve this aspect of SASW testing, a backcalculation technique that is based on the generalized inverse theory is developed. The technique provides a fast and automated procedure for simultaneously determining layer elastic moduli and thickness of pavements. In addition, some description of uncertainty in the backcalculated results is provided. The development of this algorithm is discussed and the speed and accuracy as well as the limitations of the algorithm are demonstrated. An actual field case history is included to exhibit the usefulness of the method in actual field testing.

This paper appears in Transportation Research Record No. 1377, Nondestructive Deflection Testing and Backcalculation for Pavements, Proceedings of a Symposium, August 19-21, 1991, Nashville, Tennessee. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01404955

English

p. 159-166

1992

Transportation Research Record

0309054206

Figures (8) ; References (22) ; Tables (6)

Accuracy; Algorithms; Backcalculation; Case studies; Field tests; Layer coefficient (Pavements); Modulus; Modulus of elasticity; Nondestructive tests; Optimization; Pavements; Rayleigh waves; Spectrum analysis; Thickness; Uncertainty

Spectral analysis of surface waves

Layer moduli; Limitations; Pavement thickness; Rapid methods

Data and Information Technology; Design; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces

TRIS, TRB, ATRI

Apr 5 1993 12:00AM

• ASPHALT THICKNESS VARIATION ON TEXAS STRATEGIC HIGHWAY RESEARCH PROGRAM SECTIONS AND EFFECT ON BACKCALCULATED MODULI
• BACKCALCULATION OF DESIGN PARAMETERS FOR RIGID PAVEMENTS
• COMPARISON OF BACKCALCULATED MODULI FROM FALLING WEIGHT DEFLECTOMETER AND TRUCK LOADING
• COMPARISON OF PAVEMENT DEFLECTION ANALYSIS METHODS USING OVERLAY DESIGN
• COMPARISON OF THEORETICAL AND IN SITU BEHAVIORS OF A FLEXIBLE PAVEMENT SECTION
• CONCRETE PAVEMENT BACKCALCULATION RESULTS FROM FIELD STUDIES
• CORRELATION BETWEEN BACKCALCULATED AND LABORATORY-DETERMINED ASPHALT CONCRETE MODULI
• EFFECT OF THICKNESS AND TEMPERATURE CORRECTIONS ON PREDICTION OF PAVEMENT STRUCTURAL CAPACITY USING FALLING WEIGHT DEFLECTOMETER DATA
• IMPLEMENTATION OF BACKCALCULATION IN PAVEMENT EVALUATION AND OVERLAY DESIGN IN OREGON
• IMPLEMENTATION OF FALLING WEIGHT DEFLECTOMETER LOAD-ZONING PROCEDURE IN TEXAS
• INFLUENCE OF STATISTICAL VARIATION IN FALLING WEIGHT DEFLECTOMETERS ON PAVEMENT ANALYSIS
• INTERPRETATION OF BACKCALCULATED LAYER MODULI OF CRACK-AND-SEAT PAVEMENT FROM FALLING WEIGHT DEFLECTOMETER DATA
• LAYER MODULI DETERMINATION DURING FREEZE-THAW PERIODS
• LAYER MODULI FROM DEFLECTION MEASUREMENTS: SOFTWARE SELECTION AND DEVELOPMENT OF STRATEGIC HIGHWAY RESEARCH PROGRAM'S PROCEDURE FOR FLEXIBLE PAVEMENTS
• MODELING MATERIAL NONLINEARITY IN A PAVEMENT BACKCALCULATION PROCEDURE
• NONDESTRUCTIVE TESTING WITH FALLING WEIGHT DEFLECTOMETER ON WHOLE AND BROKEN ASPHALT CONCRETE PAVEMENTS
• REPORT OF THE DISCUSSION GROUP ON BACKCALCULATION LIMITATIONS AND FUTURE IMPROVEMENTS
• REPORT OF THE DISCUSSION GROUP ON CURRENT AND FUTURE APPLICATIONS OF NONDESTRUCTIVE DEFLECTION MEASUREMENTS
• REPORT OF THE DISCUSSION GROUP ON PRACTICAL LIMITATIONS AND WHAT CAN BE DONE TO OVERCOME THEM
• STRATEGIC HIGHWAY RESEARCH PROGRAM FALLING WEIGHT DEFLECTOMETER QUALITY ASSURANCE SOFTWARE
• VALIDATION OF MODULI BACKCALCULATION PROCEDURE USING MULTIDEPTH DEFLECTOMETERS INSTALLED IN VARIOUS FLEXIBLE PAVEMENT STRUCTURES
• VARIABILITY IN MEASURED DEFLECTIONS AND BACKCALCULATED MODULI FOR THE STRATEGIC HIGHWAY RESEARCH PROGRAM SOUTHERN REGION