The influence of frequency normalisation of FWD pavement measurements on backcalculated values of stiffness moduli

Abstract

Backcalculation is commonly used for determining stiffness moduli of pavement courses and its subgrade based on in situ deflection tests. However, the in situ test results are dependent on the frequency domain, which in turn has a significant influence on the backcalculation results. In this paper, one of the methods for normalising the frequency of load and displacement functions obtained from a dynamic impulse generated by a falling weight deflectometer (FWD) test is verified. The assessment of the method is carried out based on backcalculation results of pavement deflection tests induced by both the dynamic and static loads and an independent numerical experiment. The analysis carried out in this paper shows that the normalisation of vertical displacements and pavement loads to the values corresponding to the frequency of 0 Hz improves the accuracy of the backcalculation results. It can be concluded that the frequency normalisation procedure is an effective way for standardising the boundary conditions in the backcalculation of flexible pavements.

Keywords:

• pavement diagnostic
• backcalculation
• FWD
• frequency normalisation
• deflection
• stiffness modulus

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Andrzej Pożarycki http://orcid.org/0000-0002-1321-066X

Przemysław Górnaś http://orcid.org/0000-0002-0632-4191

Dariusz Wanatowski http://orcid.org/0000-0002-5809-0374

Additional information

Funding

This work has been partially supported by the Polish National Centre for Research and Development [grant number PBS3/B6/38/2015]. The last author would also like to acknowledge the financial support from the National Natural Science Foundation of China [grant number 51408326].