Assess Subgrade Rutting Potential by Stress Factor

The problem of subgrade rutting is an important factor in the overall structural design system of flexible pavements. This paper introduces the parameter stress factor in pavement design and research as an expedient and useful test to check the subgrade rutting potential in a flexible pavement. The larger the computed stress factor in the subgrade is, the greater the potential of the pavement to rut. If several different types of pavements are designed for a given subgrade soil and for a given aircraft load at the same performance level, the pavement with the largest stress factor will most probably have the greatest potential of subgrade rutting. Also for a given subgrade soil, if two pavements are designed for two different aircraft loads at the same performance level, the heavier aircraft load will have a greater stress factor in the subgrade.