Abstract: Test data of water absorption rate, porosity and uniaxial compression of the gypsum rocks from Shiziya tunnel in Badong were obtained through 0, 1, 3, 6, 12 cycles of drying and wetting test. Results showed that the water absorption rate and porosity of gypsum rock were in logarithmic function relationship with the wet-dry cycles. With the increase of wet-dry cycle, water absorption rate and porosity both increased; but the increment alleviated. Meanwhile, the uniaxial compressive strength and elastic modulus both reduced with the number of wet-dry cycles; and the reduction decreased gradually. Furthermore, dry-wet cycles had biggest degradation effect on water absorption rate, followed by elastic modulus, uniaxial compressive strength, and porosity.

Key words: gypsum rock, dry-wet cycle, water absorption rate, porosity, uniaxial compression test, degradation effect