Predicting settlement of road on soft subsoil induced by moving traffic load

The acting position of traffic load moves on road surface with certain velocity. The induced stresses in subsoil imposed by traffic load depend on the moving velocity of load, whereas the simplified procedures nowadays used for induced stresses calculation by traffic load have ignored this velocity effect. The paper studies the long-term settlement of road on soft subsoil with emphasis on the velocity effect of moving traffic load. The numerical integration method is employed to get the induced stresses in the elastic half-space by a surficial moving point load with uniform velocity. By analyzing the characteristics of the induced stresses, a practical procedure is proposed for calculating traffic-load-induced stresses in road subsoil, which combines the results of commonly-used pseudo method with two amplification coefficients accounting for velocity effect. In the other aspect, an empirical model is proposed for quantifying the accumulation of residual strain during the long-term repeated cycles of heart-shaped stress paths, a typical stress path-induced by surficial moving load. The proposed empirical model is validated by the simulated test results. Once the induced stresses and residual strain of the subsoil can be calculated, the road settlement prediction is straightforward following the layer-wise summation procedure. The Saga airport road is taken as an example to analyze the influence of vehicle moving speed on long-term settlements.