NUMERICAL SIMULATION OF RIGID PAVEMENT BEHAVIOR TO NON-DESTUCTIVE IMPULSE RESPONSE TESTING

Abstract

The Impulse Response (IR) technique is a stress wave method that measures the structure’s response
to stress waves generated by an impact source. When applied to rigid pavements, the measured response contains
complex information on the dynamic pavement properties that is primarily used in detection of voids or loss of
support, and softening of the subgrade. The dynamic response of the pavement system is assumed to be similar to
that of a single degree of freedom (SDOF) system. This assumption is useful for practical purposes but introduces
inconsistencies and uncertainties in the data interpretation because it oversimplifies a complex dynamic problem.
Results of a Finite Element parametric study analysis conducted to identify key factors that influence rigid
pavement response during Impulse Response (IR) testing are presented. A dynamic modal analysis of a multilayer
rigid pavement, assuming viscoelastic and elastic linear material properties, indicates that the mobility spectra
from IR testing is predominantly influenced by the properties of the surface layer and the subgrade. The presence
of voids beneath a rigid pavement results in increased mobility and less damped behavior of the pavement. The
validity of the SDOF assumption in void detection in the reduction of field IR data is also examined.