Numerical simulation of falling/heavy weight deflectometer test considering linear viscoelastic behaviour in bituminous layers and inertia effects

Falling (or Heavy) Weight Deflectometer (F/HWD) is a widely used non-destructive device for pavement evaluation. The falling mass system of this device can generate a load representative of a wheel. Deflections are monitored by geophones at several distances from the loading centre. Interpretation of F/HWD deflections is classically done using a static elastic method. However, the F/HWD test is clearly dynamic and the mechanical behaviour of bituminous materials is most likely linear viscoelastic at the temperature and strain conditions of the test. This paper aims at exploring the differences due to the consideration of dynamic and viscoelastic effects of the pavement structure in the numerical simulation of the F/HWD test. Deflections of an existing pavement structure were numerically simulated through a time-domain finite element method. Four numerical simulations are proposed: static elastic, dynamic elastic, static viscoelastic and dynamic viscoelastic. This study shows that dynamic and viscoelastic effects significantly affect time-history and peak values of simulated deflections.