A new pavement design procedure for frost protection in seasonal frost areas

Differential frost heave and uneven degradation of flexible pavements surface profile in cold climate significantly affects the serviceability of these important civil engineering structures. Among the factors influencing this phenomenon, subgrade soils variability is documented as a significant parameter to consider, especially regarding differential frost heave. Subgrade soils variability may increase in urban area because of the buried utilities and the numerous cuts, both usually filled with granular materials. Therefore, past researches were revisited to implement a design methodology for frost heave protection of flexible pavements in northern environment based on the risk of differential frost heave caused by subgrade soils variability. Previous data were used to 1. Propose a relationship between the maximum pavement IRI, usually encountered at the end of the winter period, the design period and the subgrade soils longitudinal variability index, and 2. Quantify the effect of the replacement of in situ subgrade soils with granular fill on the coefficient of variation of frost heave. The relationship was used as a reference to identify allowable average frost heave based on subgrade soils variability conditions. This is specifically applicable in the urban context for which granular fills, and consequently supplementary induced soil variability, is the main factor contributing to the determination of the allowable frost heave. Working examples of various classes of urban pavements allowed obtaining allowable frost heave criteria that take into account subgrade soils variability, design period and maximum allowable roughness, which are also in good agreement with available data in the literature.