关键词: 膨胀土, 胀缩特性, 渗透特性, 压实度, 干密度

Abstract: A series of tests for characteristics of swelling-shrinkage and permeability are carried out on Jingmen weak expansive soil under five different compactnesses and on the lime-treated soil. The test results show that the swelling pressure - dry density relation can be represented by a power function; while the relations between non-loaded swelling ratio, linear swelling ratio, volume shrinkage ratio and dry density are all non-monotonous. The expansive soil with the compactness of 95 % has the lower swelling ratio and volumetric shrinkage ratio, which is due to effects of coupled compaction and swelling. Therefore, the compactness should be selected as 95 % in weak expansive soil embankment construction. On the other hand, the lime treatment can reduce swelling and shrinkage of expansive soil, indicating by the fact that the swelling-shrinkage total ratio of the lime-treated expansive soil is only 0.7 %. In addition, the permeability coefficient of the lime-treated and untreated expansive soil all decrease with increasing dry density. This relation can be represented by the power function as well. The permeability coefficient of the lime-treated soil is larger than that of the untreated expansive soil under the same compactness; however, for the approximate dry density, the difference of the permeability coefficient between the two types of soil is not large

Key words: expansive soil, swelling-shrinkage characteristics, permeability characteristics, degree of compaction, dry density