Influences of Freezing and Thawing on Water Resistance of Soil

Studies on characteristics of frost and thawy soils (V)

Abstract

The purpose of this report is to examine the soil erosion during spring thawing in the areas where the ground is frozen in winter. Experiments for research were carried out of the freezing and thawing effects on the soil loss from sloped bare ground and the water-resistances of soil aggregate and soil mass. The information obtained is summarized as follows:
1) The surface runoff and soil loss from the bare slopes tend to decrease with year, which is partially attributed to the structural changes of the ground due to its freezing and thawing (Figs. 1 to 3).
2) The results of soil erosion experiments on soil specimens subjected to artificial freezing and thawing revealed that the amount of soil loss was far less for the pre-frozen sample than for the unfrozen sample (Fig. 5).
3) A comparison in terms of infiltration line of the unfrozen soil and the pre-frozen soil revealed that the infiltration intensity and linear gradient were grater for the pre-frozen soil than for the unfrozen soil, suggesting soil structural changes caused by freezing and thawing (Fig. 6).
4) The soil concentratio4 of surface runoff is tendentially smaller for the pre-frozen soil than for the unfrozen soil (Fig. 7).
5) The mean weight diameter of the soil aggregate, though changed by freezing and thawing, varies with different initial moisture content (Figs. 8 and 9).
6) The degree of influence of freezing and thawing on the water resistance of soil mass varies with the properties of soils, but is generally lowered by freezing and thawing. With organic soils, however, no such effects were observed (Table 5 and Fig. 13).
7) As for the organic soils with high stability, air-drying treatments contributed to the onset of the freezing and thawing effect, thus lowering its water resistance (Table 6 and Fig. 14).