Abstract: Expansive soil cracking induced by the expansion and contraction under the wetting-drying cycles is a common engineering problem in the geotechnical construction projects. Remolded expansive soil samples were laboratory simulated by the impact of wetting-drying cycle under natural conditions. The fracture development patterns were digital imaging processing technique. Under various initial expansive soil samples, the cracking ratio, total cracking lengths and average width of cracks were quantitively extracted and processed. In additional to the digital crack processing and evaluation, the direct shear tests were conducted on samples underwent the wetting-drying cycles. The results indicate that, the initial moisture content and initial dry density are the major factors affecting the cracking development. Higher initial dry density sample developed cracks at earlier stage and resulted larger cracking ratio. Number of wettingdrying cycles and initial dry density had also affected the sample shear strength. The initial friction angle was influenced by the number of wetting-drying cycles and the cohesion value reduced with the increase of wetting-drying cycles.

Key words: Initial Soil Sample State, Expansive Soils, WettingDrying Cycles, Crack Development, Shear Strength