INFLUENCE OF SALT AND COMPACTION ON CRITICAL WATER CONTENT OF FROST HEAVING OF SALINE SOIL

Frost heaving hazards of saline soil in seasonal region affect engineering quality. The change of water, density and salt influences the frost heaving characteristics of seasonal soil. By taking the saline soil from dry land in Nong'an County, Jilin province, frost heaving tests are conducted to examine the frost heaving regularity of saline soil with different water contents, compaction degrees and salt contents. Under different water contents, compaction degrees and salt contents, the changing rule of the critical water content of frost heaving of saline soil is analyzed. The research indicates that higher compaction degree and higher water content are in favor of frost heaving. In lower water content and lower compaction degree, shrinkage occurs. Shrinkage disappears and then expansion appears with the increase of water content and compaction degree. Frost heaving quantity and water content have a nearly linear relationship. Therefore, a critical water content of frost heaving exists. The critical water content decreases in a linear rule with the increase of compaction degree. But as the salt content increases, the critical water content rises generally. The influence of plastic limit and compaction degree on the critical water content of frost heaving can be fitted in a linear equation. The coefficient of the equation rises overall with the increase of salt content. On the basis of the formula summed up previously, a new parameter, compaction degree has been added, which provides reference and theoretical basis for the research of the frost heaving characteristics of seasonal saline soil in future.