By a lot of laboratory tests of expansive soil

in the case of expansive soil in Shaoyang city of Hunan province

the engineering deformation characteristics of three kinds of expansive soils have been test studied. The test results indicate: the beginning water content and dried density of expansive soil are the main outside factors that influence the magnitude of their expansibility and swelling quantity; according to the data of expansibility tests and swelling quantity tests

the variational rule of both expansibility fitted curve and swelling quantity fitted curve is the same exponential relation. At the same time

the characteristic curve and the similar relation between the curve of swelling velocity and the curve of shrinkage tests have been studied. Therefore

the study results have provided the important basis for the design of embankment and treatment technique to the existing expansive soil foundation.