Abstract: The generation of shrinkage cracks in expansive soil in wetting-drying cycle is related to its tensile strength, which must be considered in researching the swell-shrink mechanism of expansive soil as it plays an important role in resisting the development of dry shrinkage cracks. In this research, compacted cylindrical specimens of expansive soil from Gaochun, Nanjing are taken for tensile strength test with axial compress fracture method to investigate the influences of different factors such as degree of compaction, initial moisture content, specimen preparation method, degree of saturation and suction of compaction on tensile strength. Results show that 1) tensile strength of compacted expansive soil increases with the increase of degree of compaction, but decreases with the increase of moisture content; 2) tensile strength can be weakened both by losing water and absorbing water, and the weakening by the latter is more obvious; 3) when the sample changes from unsaturated state to saturated state, its tensile strength reduces remarkably with the reducing ratio up to 80%.

Key words: expansive soil, degree of compaction, CBR, tensile strength, axial compression fracture method