Chunmei Chu, Longwei Yang, Wenyu Cheng, Juncheng Wang, Xiang Wang
{"title":"伊犁黄土冻融后的三轴力学行为","authors":"Chunmei Chu, Longwei Yang, Wenyu Cheng, Juncheng Wang, Xiang Wang","doi":"10.3389/feart.2024.1454629","DOIUrl":null,"url":null,"abstract":"Loess is strongly sensitive to water, and its properties are substantially affected by weathering and other factors. Loess landslides, which are widely distributed in Ili, are closely related to seasonal freeze–thaw effects. In this study, multiple freeze–thaw cycle tests were conducted on loess samples with different moisture contents from the Ili region, and triaxial shear tests were conducted to study mechanical characteristics of the loess. Variations in the microstructure of the loess samples were analysed using scanning electron microscopy images to reveal the underlying mechanisms. The results showed that the freeze–thaw cycles significantly influence failure mode of the stress–strain curve of loess samples with a lower moisture content of 10%, which transitioned from strain softening to strain hardening with six cycles as the turning point, whereas the stress–strain curve transitioned from strong to weak hardening for the loess samples with higher moisture content of 18%. As the number of freeze–thaw cycles increased, failure strength and shear strength parameters of loess gradually decreased, and tended to stabilize after the 10th cycle. In addition, strength parameters deterioration is most significant after the first cycle, and the degree of cohesion deterioration was much greater than that of internal friction angle. Cohesion and internal friction angle showed attenuation exponential function and polynomial function relationship, respectively, with the number of freeze–thaw cycles, and their fitting parameters underwent a sudden change with increasing moisture content, with 14% as the turning point. Microscopic SEM revealed that the number of overhead pores increased, and point–to–point contact between particles increased after freeze–thaw, which was consistent with increase in of loess porosity. This revealed the fundamental reason for the significant deterioration in loess strength caused by freeze–thaw cycles.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"3 1","pages":""},"PeriodicalIF":2.0000,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Triaxial mechanical behaviours of Ili loess after freeze–thaw\",\"authors\":\"Chunmei Chu, Longwei Yang, Wenyu Cheng, Juncheng Wang, Xiang Wang\",\"doi\":\"10.3389/feart.2024.1454629\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Loess is strongly sensitive to water, and its properties are substantially affected by weathering and other factors. Loess landslides, which are widely distributed in Ili, are closely related to seasonal freeze–thaw effects. In this study, multiple freeze–thaw cycle tests were conducted on loess samples with different moisture contents from the Ili region, and triaxial shear tests were conducted to study mechanical characteristics of the loess. Variations in the microstructure of the loess samples were analysed using scanning electron microscopy images to reveal the underlying mechanisms. The results showed that the freeze–thaw cycles significantly influence failure mode of the stress–strain curve of loess samples with a lower moisture content of 10%, which transitioned from strain softening to strain hardening with six cycles as the turning point, whereas the stress–strain curve transitioned from strong to weak hardening for the loess samples with higher moisture content of 18%. As the number of freeze–thaw cycles increased, failure strength and shear strength parameters of loess gradually decreased, and tended to stabilize after the 10th cycle. In addition, strength parameters deterioration is most significant after the first cycle, and the degree of cohesion deterioration was much greater than that of internal friction angle. Cohesion and internal friction angle showed attenuation exponential function and polynomial function relationship, respectively, with the number of freeze–thaw cycles, and their fitting parameters underwent a sudden change with increasing moisture content, with 14% as the turning point. Microscopic SEM revealed that the number of overhead pores increased, and point–to–point contact between particles increased after freeze–thaw, which was consistent with increase in of loess porosity. 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Triaxial mechanical behaviours of Ili loess after freeze–thaw
Loess is strongly sensitive to water, and its properties are substantially affected by weathering and other factors. Loess landslides, which are widely distributed in Ili, are closely related to seasonal freeze–thaw effects. In this study, multiple freeze–thaw cycle tests were conducted on loess samples with different moisture contents from the Ili region, and triaxial shear tests were conducted to study mechanical characteristics of the loess. Variations in the microstructure of the loess samples were analysed using scanning electron microscopy images to reveal the underlying mechanisms. The results showed that the freeze–thaw cycles significantly influence failure mode of the stress–strain curve of loess samples with a lower moisture content of 10%, which transitioned from strain softening to strain hardening with six cycles as the turning point, whereas the stress–strain curve transitioned from strong to weak hardening for the loess samples with higher moisture content of 18%. As the number of freeze–thaw cycles increased, failure strength and shear strength parameters of loess gradually decreased, and tended to stabilize after the 10th cycle. In addition, strength parameters deterioration is most significant after the first cycle, and the degree of cohesion deterioration was much greater than that of internal friction angle. Cohesion and internal friction angle showed attenuation exponential function and polynomial function relationship, respectively, with the number of freeze–thaw cycles, and their fitting parameters underwent a sudden change with increasing moisture content, with 14% as the turning point. Microscopic SEM revealed that the number of overhead pores increased, and point–to–point contact between particles increased after freeze–thaw, which was consistent with increase in of loess porosity. This revealed the fundamental reason for the significant deterioration in loess strength caused by freeze–thaw cycles.
期刊介绍:
Frontiers in Earth Science is an open-access journal that aims to bring together and publish on a single platform the best research dedicated to our planet.
This platform hosts the rapidly growing and continuously expanding domains in Earth Science, involving the lithosphere (including the geosciences spectrum), the hydrosphere (including marine geosciences and hydrology, complementing the existing Frontiers journal on Marine Science) and the atmosphere (including meteorology and climatology). As such, Frontiers in Earth Science focuses on the countless processes operating within and among the major spheres constituting our planet. In turn, the understanding of these processes provides the theoretical background to better use the available resources and to face the major environmental challenges (including earthquakes, tsunamis, eruptions, floods, landslides, climate changes, extreme meteorological events): this is where interdependent processes meet, requiring a holistic view to better live on and with our planet.
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