On the base of practical data in concrete project,conclusions have drawn as follows:CBR expansive rate has definite correlativity with total rate of swelling-shrinkage,and in engineering practice,CBR expansive rate could be used to determine the expansive behavior and classification index instead of total rate of swelling-shrinkage in the project of expressway.

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 bot.

The effects of expansion pattern and expansion rate on fracture resistance of cement- expanded composite screw post;

A method of determination of reduced suction based on the principle of equivalence of deformation is introduced;and the reduced suction is used as an essential variable in the earth pressure calculation of unsaturated soils on retaining wall and swell increment.