Elliptic model for prediction of deflections induced by a Light Falling Weight Deflectometer

The use of a portable lightweight deflectometer for construction quality control and road construction is increasing around the world. However there are some points of weakness that have been poorly investigated in the past. One of them is the definition of the domain of influence of the deflectometer for various test setups and different soils. This paper proposes a new model based on the Boussinesq theory that has been calibrated using the outcome of experimental tests. The series of laboratory and field scale investigations that are presented here are not conventional. In particular the actual deep deflections have been measured under the surface using an original experiments setup. Using the calibrated model, it is also suggested that a revised version of the corrected Boussinesq equation be used to better represent stress distribution in soil, where a second parameter is included along with the so called Froehlich concentration factor.