00625548

Component

http://onlinepubs.trb.org...trr/1992/1355/1355-010.pdf

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

The authors present a simple elastostatic approach to estimate a suitable subgrade modulus from falling weight deflectometer (FWD) data. An effective surface modulus is defined on the basis of Boussinesq-Newmark equations. Deviations between the model assumptions and actual in situ conditions are reflected in the effective surface modulus variation with radius. The variation indicates which sensor readings are suitable for backcalculation. The presence of a shallow bedrock, increase in subgrade modulus with depth, or anisotropic properties may lead to nonconservative estimates of subgrade modulus. Assuming that the deflections at the subgrade surface (not directly under the load) may be approximated by the surface deflections, the Boussinesq-Odemark equations are used to define an effective subgrade modulus. In order to determine the subgrade modulus, the equivalent thickness of the pavement structure, which reflects pavement stiffness, is estimated by fitting preselected normalized deflections. Given the equivalent thickness, an effective subgrade modulus profile is established, from which a design subgrade modulus may be determined. An example using data of the Canadian Strategic Highway Research Program (C-SHRP) demonstrates the approach. The uniformity of the subgrade at the C-SHRP site is studied by considering the spectral density functions of the FWD time histories. The group velocity is used to define a weighted average profile modulus. The profile moduli of the two sections studied were higher but consistent with subgrade moduli estimated using elastostatic analysis.

This paper appears in Transportation Research Record No. 1355, Nondestructive Structural Evaluation of Pavements. 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

01405034

English

p. 82-89

1992

Transportation Research Record

030905219X

Figures (8) ; References (17)

Analysis; Coefficient of subgrade reaction; Elastomers; Estimating; Falling weight deflectometers

Canadian Strategic Highway Research Program (C-SHRP)

Data; Interpretation

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

TRIS, TRB, ATRI

Dec 16 1993 12:00AM

• ALTERNATIVE METHOD FOR TEMPERATURE CORRECTION OF BACKCALCULATED EQUIVALENT PAVEMENT MODULI
• COMPREHENSIVE EVALUATION OF FIVE SENSORS USED TO MEASURE PAVEMENT DEFLECTION
• EFFECT OF DEPTH TO BEDROCK ON DEFLECTION BASINS OBTAINED WITH DYNAFLECT AND FALLING WEIGHT DEFLECTOMETER TESTS
• EFFECTS OF BUFFERS ON FALLING WEIGHT DEFLECTOMETER LOADINGS AND DEFLECTIONS (WITH DISCUSSION)
• ESTIMATING DAMAGE EFFECTS OF DUAL VERSUS WIDE BASE TIRES WITH MULTIDEPTH DEFLECTOMETERS
• EVALUATION OF A DUAL-LOAD NONDESTRUCTIVE TESTING SYSTEM TO BETTER DISCRIMINATE NEAR-SURFACE LAYER MODULI
• FIELD AND LABORATORY DETERMINATION OF ELASTIC PROPERTIES OF PORTLAND CEMENT CONCRETE USING SEISMIC TECHNIQUES
• MODELING OF GROUND-PENETRATING RADAR WAVE PROPAGATION IN PAVEMENT SYSTEMS
• NONLINEAR EFFECTS IN FALLING WEIGHT DEFLECTOMETER TESTS
• RADAR PAVEMENT THICKNESS EVALUATIONS FOR VARYING BASE CONDITIONS
• VARIABILITY IN ESTIMATION OF STRUCTURAL CAPACITY OF EXISTING PAVEMENTS FROM FALLING WEIGHT DEFLECTOMETER DATA