Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes
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 tr...
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MDPI AG
2023-09-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/15/19/3382 |
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| author | Yongliang Zhang Zizhao Zhang Wanhong Hu Yanyang Zhang Guangming Shi Yamei Wang |
| author_facet | Yongliang Zhang Zizhao Zhang Wanhong Hu Yanyang Zhang Guangming Shi Yamei Wang |
| author_sort | Yongliang Zhang |
| collection | DOAJ |
| description | 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. |
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| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-09T13:52:07Z |
| publishDate | 2023-09-01 |
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| series | Water |
| spelling | doaj.art-74240ee408c94870999bc05a96ecf2362023-11-30T20:49:16ZengMDPI AGWater2073-44412023-09-011519338210.3390/w15193382Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling ModesYongliang Zhang0Zizhao Zhang1Wanhong Hu2Yanyang Zhang3Guangming Shi4Yamei Wang5School of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, ChinaSchool of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, ChinaSchool of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, ChinaSchool of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, ChinaSchool of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, ChinaSchool of Geological and Mining Engineering, Xinjiang University, Urumqi 830017, ChinaIn 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.https://www.mdpi.com/2073-4441/15/19/3382Yili loesswet–dry cyclesfreeze–thaw cyclessoil shear strength attenuationinternal friction anglecohesion |
| spellingShingle | Yongliang Zhang Zizhao Zhang Wanhong Hu Yanyang Zhang Guangming Shi Yamei Wang Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes Water Yili loess wet–dry cycles freeze–thaw cycles soil shear strength attenuation internal friction angle cohesion |
| title | Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes |
| title_full | Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes |
| title_fullStr | Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes |
| title_full_unstemmed | Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes |
| title_short | Shear Strength of Loess in the Yili Region and Corresponding Degradation Mechanisms under Different Cycling Modes |
| title_sort | shear strength of loess in the yili region and corresponding degradation mechanisms under different cycling modes |
| topic | Yili loess wet–dry cycles freeze–thaw cycles soil shear strength attenuation internal friction angle cohesion |
| url | https://www.mdpi.com/2073-4441/15/19/3382 |
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