Influences of freeze-thaw on strength of loess under complex stress path

In order to investigate the influences of freeze-thaw on the strength characteristics of loess under complex stress path, the true-triaxial apparatus is used to carry out consolidation drained shear tests under the constant p stress path for the remolded loess experiencing different freeze-thaw cycles. In the freeze-thaw tests, the samples are set to go through five different freeze-thaw cycles as 0, 1, 3, 5 and 10. In the shear tests, the constant spherical stress p is controlled as 200, 300 and 400 kPa, and the b-values of the five intermediate principal stress parameters are respectively set at the value of 0, 0.25, 0.5, 0.75 and 1. The stress-strain curve of remolded loess and the strength failure line on the p-q surface of remolded loess are given. The influences of freeze-thaw cycles on the stress-strain curves of soil under different b-value conditions and the effects of freeze-thaw and b-values on the strength parameters of remolded loess are discussed. The results show that the freeze-thaw cycles have little effect on the shape of the stress-strain curve of soil, while the change of b-value has significant effect on the shape. The shear strength first decreases and then slightly increases with the number of freeze-thaw, and finally tends to be stable, while it decreases with the value of b. The cohesion first decreases with the number of freeze-thaw cycles and then tends to be stable, while it increases with the b-value and then decreases. The internal friction angle fluctuates irregularly in a small range with the number of freeze-thaw cycles, while it increases first and then decreases with the value of b in a small range. © 2021, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.