Abstract: The existence of hydrophilic minerals causes expansive soil to swell and shrink when it absorbs and loses water. When the shrinkage stress is greater than the sum of compressive stress and tensile strength, cracks occur. To study the tensile strength of expansive soil during the drying-wetting process, a self-made testing device was used in this study to conduct uniaxial tensile tests on undisturbed and compacted Nanyang expansive soil experiencing the drying-wetting process. The change in tensile strength was obtained during a drying-wetting cycle. Directly compacted specimens and compacted-drying specimens were prepared to study the effect of the specimen preparation method on tensile strength. Test results show that when the water content of undisturbed and compacted specimens decreases, the tensile strength and dry density increase, and the compacted one increases more rapidly. When the water content increases, the tensile strength of undisturbed and compacted specimens drops rapidly at first and then tends to remain unchanged. According to the soil-water characteristic curves of undisturbed and compacted specimens in the drying-wetting, an equation and corresponding parameter values for predicting the tensile strength of Nanyang expansive soil in the drying-wetting process are obtained.

Key words: expansive soil, tensile strength, drying-wetting process, suction, prediction