Vol16 No.9: 2159-2170
【Title】Effect of freeze-thaw cycles on uniaxial mechanical properties of cohesive coarse-grained soils
【Author】QU Yong-long1; CHEN Guo-liang2; NIU Fu-jun3, 4; NI Wan-kui1; MU Yan-hu3*; LUO Jing3
【Addresses】1 College of Geology Engineering and Geomatics, Chang′ an University, Xi′an 710054, China; 2 China Gold Group Tibet Tyrone Mining Development Co., Ltd., Tibet 850000, China; 3 State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; 4 South China Institute of Geotechnical Engineering, School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510641, China
【Corresponding author】MU Yan-hu
【Citation】Qu YL, Chen GL, Niu FJ, et al. (2019) Effect of freeze-thaw cycles on uniaxial mechanical properties of cohesive coarse-grained soils. Journal of Mountain Science 16(9). https://doi.org/10.1007/s11629-019-5426-7
【Abstract】Freeze-thaw cycles are closely related to the slope instability in high-altitude mountain regions. In this study, cohesive coarse-grained soils were collected from a high-altitude slope in the Qinghai–Tibet Plateau to study the effect of cyclic freeze-thaw on their uniaxial mechanical properties. The soil specimens were remolded with three dry densities and three moisture contents. Then, after performing a series of freeze-thaw tests in a closed system without water supply, the soil specimens were subjected to a uniaxial compression test. The results showed that the stress-strain curves of the tested soils mainly performed as strain-softening. The softening feature intensified with the increasing dry density but weakened with an increase in freeze-thaw cycles and moisture content. The uniaxial compressive strength, resilient modulus, residual strength and softening modulus decreased considerably with the increase of freeze-thaw cycles. After more than nine freeze-thaw cycles, these four parameters tended to be stable. These parameters increased with the increase of dry density and decreased with the increasing moisture content, except for the residual strength which did not exhibit any clear variation with an increase in moisture content. The residual strength, however, generally increased with an increase in dry density. The soil structural damage caused by frozen water expansion during the freeze-thaw is the major cause for the changes in mechanical behaviors of cohesive coarse-grained soils. With results in this study, the deterioration effect of freeze-thaw cycles on the mechanical properties of soils should be considered during the slope stability analysis in high-altitude mountain regions.
【Keywords】Freeze thaw cycles; Residual strength; Resilient modulus; Softening modulus; Uniaxial compressive strength; Slope stability