Affiliation:
1. School of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, China
2. State Key Laboratory for Geomechanics and Deep Underground Engineering, Xinjiang University, Urumqi 830017, China
Abstract
In the Yili region, China, complex environmental conditions induce repeated wet–dry (WD) and freeze–thaw (FT) cycles, deteriorating soil shear strength and producing frequent loess landslides. In this study, we collected soil samples from the Alemale landslide, Yili Prefecture and performed their triaxial shear tests with different numbers of WD, FT, and WD-FT cycles. In addition, we summarized the change mechanisms of loess mechanical properties and its deterioration, in the Yili region, under different cyclic effects. Subsequently, the test results under the three cycling modes were compared and analyzed, the differences in the deterioration effects of different cyclic conditions on loess were discussed in depth, and finally, a multiple linear regression model was established and the weights of single factors under the action of coupled cycles were analyzed. The results show the following: (1) Regardless of the confining pressure values, the principal stress evolution trends in soil samples under different cycling modes were generally consistent, i.e., after an initial increase, peak values were reached, followed by a final decline. (2) Under unconsolidated undrained (UU) conditions, shear strength values of all soil samples tested under the three cycling modes dropped after the first twenty cycles, exhibiting different evolution patterns. (3) Coupled WD-FT cycling most significantly promoted soil shear strength degradation, with less WD cycling effect, and FT cycling had the least significant effect; in all three modes, the first cycle had the highest contribution to this effect. From the perspectives of cohesion, angle of internal friction, and decay of shear strength attenuation, the coupled WD-FT cycling effect on soil shear strength could not be reduced to a simple single-factor addition–subtraction relationship. (4) Weight analysis of soil samples after WD, FT, and WD-FT cycling revealed that WD cycles in the coupled WD-FT cycling mode had the most significant impact on the shear strength attenuation of soil samples (contributing 57%), FT cycles had a medium impact (contributing about 33%), while the effect of the total number of cycles was negligible (about 10%). The research results provide experimental and theoretical bases for subsequent control of loess landslides.
Funder
National Natural Science Foundation of China
Xinjiang Uygur Autonomous Region Special Program for Key R&D Tasks
Subject
Water Science and Technology,Aquatic Science,Geography, Planning and Development,Biochemistry
Reference34 articles.
1. Experimental Study of Wetting-Drying Cycle on Deformation Behaviors of Unsaturated Remoulded Clay;Song;Chin. J. Undergr. Space Eng.,2022
2. Analyses of the climate change and its impact on water resources in the middle reaches of Irtysh River during 1926–2009;Yu;J. Glaciol. Geocryol.,2012
3. Zhao, X. (2019). Investigation on the Influence of Freezing-Thawing Cycle and Drying-Wetting Alternation on the Permeability Anisotropy and Spatial Variability of Loess. [Master’s Thesis, Xi’an University of Architecture and Technology]. (In Chinese).
4. Variations in strength and deformation of compacted loess exposed to wetting-drying and freeze-thaw cycles;Li;Cold Reg. Sci. Technol.,2018
5. Effect of freeze-thaw cycles in mechanical behaviors of frozen loess;Zhou;Cold Reg. Sci. Technol.,2018