The influence of the soil stratification on free field traffic-induced vibrations

This paper deals with the influence of the soil stratification on the free field vibrations generated by the passage of a vehicle on an uneven road. A two-stage solution procedure is applied for the numerical prediction of th e free field traffic-induced vibrations. First, a 2D vehicle model is used for the calculation of the axle loads from the longitudinal road profile. N ext, the free field response is calculated with the dynamic Betti-Rayleigh reciprocity theorem, using a transfer function between the road and the rec eiver. The dynamic road-soil interaction problem is solved with a substruct ure method. The road is modelled as a beam of infinite length, while the bo undary element method, based on the Green's functions for a horizontally la yered linear elastic halfspace is used for the soil. The influence of the s oil stratification is demonstrated by a numerical example where the free fi eld vibrations during the passage of a vehicle on a traffic plateau are cal culated. Three different cases are considered for the layering of the soil: a homogeneous halfspace, a layer built in at its base and a layer on a hal fspace. Special emphasis goes to the dynamic interaction between the road a nd the soil. It is demonstrated that the stratification of the soil has a c onsiderable influence on both the peak particle velocity and the frequency content of the free field vibrations.