Study on Unsaturated Shear Strength Characteristics of Cement-stabilized Expansive Soil

The purposes for the modification of expansive soil are decreasing the expansive potential and improving the shear strength.The expansive soil in Nanyang section of Median-line South-to-North Water Transfer Project is selected to perform the unsaturated direct shear test of soils before and after cement modification.The results show that the free expansive ratio is reduced from 51% to 30% when the expansive soil is blended with cement of 3%.The stress-strain curves of the remoulded expansive soil samples are strain hardening owing to the complete damage of the soil structure under different matric suctions and vertical stresses,while the stress-strain curves of the cement-stabilized expansive soil samples are strain softening.The saturated shear strength parameters c′ and φ′ of the expansive soil are increased after cement modification,while the unsaturated shear strength parameter φb is also improved.A scientific and valuable basis is provided for the design and construction of site cement modification of expansive soils.