Numerical Prediction of Ground Vibrations Generated by Road Traffic and Pavement Breaking

摘要

Poor ride quality and traffic induced noise and vibrations require replacement or rehabilitation of deteriorated pavements. In the case of concrete roads, the pavement is usually broken to prepare it for removal or as the first step in the cracking and seating method of road rehabilitation. The pavement breaking operation generates a high level of ground-borne vibrations. In this study, three aspects of vibrations in the vicinity of concrete pavements are addressed: 1) the prediction of ground vibrations due to traffic on deteriorated jointed concrete pavements, 2) the prediction of vibrations generated by pavement breaking, and 3) the level of vibration reduction gained by road rehabilitation. Several experiments on traffic induced vibrations and vibrations generated by pavement breaking are conducted prior to, during, and after the rehabilitation of a deteriorated jointed concrete pavement. The road is rehabilitated with the cracking and seating technique and application of an asphalt overlay. The prediction of traffic induced vibrations is performed in two stages: first, the dynamic wheel loads due to the passage of a vehicle over road irregularities are estimated; second, these loads are applied to a road-soil system to compute the radiated wave field in the soil. The road unevenness is obtained by means of a high speed profiler and introduced into a three-dimensional vehicle model to compute the dynamic vehicle loads. The loads are subsequently applied to a coupled finite element-boundary element model of the road-soil system to compute ground vibrations. The results are in a good agreement with the experimental data and show a significant reduction of ground vibrations by road rehabilitation. For the estimation of the impact load due to the blow of a falling weight pavement breaker, a numerical model is developed and experimentally validated. The energy dissipated by fracturing of concrete is found to be negligible and, consequently, can be disregarded when predicting ground vibrations. Hence, the linear coupled finite element-boundary element model of the road-soil system is adopted to predict ground vibrations generated by pavement breaking. The strain level in the soil is found to be beyond the linear elastic range. Therefore, the model is further elaborated to an equivalent linear model and subsequently to a non-linear model which takes into account inelastic behaviour of the soil and slab uplifting. It is composed of a finite element model for the slab and a part of the soil coupled to viscous boundary conditions. To compute the response outside the finite element domain, the tractions and displacements along a path inside the finite element domain are computed and introduced in the integral representation formulation. Ground vibrations predicted with the non-linear model are compared to the experimental results where a relatively good agreement is observed.