Abstract:With compacted expansive soil in Ankang city of Shanxi province,by a series of swelling capacity laboratory tests with different initial dry densities,moisture contents and pressures,the characteristics of swelling deformation with the above three parameters were found. The calculation methods of swelling capacity of compacted expansive soils,which can fulfil the accuracy requirements of engineering and take into account the coupling effects between initial dry density,initial moisture content and pressure,are summarized. The correctness of the pattern has been confirmed too. In engineering,the pattern can be utilized to calculate swelling deformation of compacted expansive soil,which can have any initial dry density,initial moisture content and pressure,with several swelling capacity tests to obtain the parameters.