Abstract：Water temperature state of an old subgrade in frost regions might change significantly when it is widened. If old water temperature state is not accurately analyzed and calculated, all kinds of damages of subgrade and pavement in the joints between the old places and new places may become possible. This paper analyzes different water temperature states in widening subgrade, as connection between the original and widening subgrades in the frost regions. One may identify the beginning stage, stagnant stage, freezing stage, saturated moisture stage and complete melting stage on the basis of previous studies. The calculation formula for the amount of surplus water is derived with the help of the seepage theory of soil, and some technological measures are proposed to improve the water temperature state and to keep the subgrade in a middle-wet state. The results show that these measures and formulas can help to reduce various kinds of damages of subgrade and pavement in the joints.
2009, Vol. 27 
