岩土力学2024，Vol.45Issue(7)：2050-2060,11.DOI:10.16285/j.rsm.2023.1281
干湿-冻融循环条件下湿陷性黄土剪切及压缩特性的劣化规律
Deterioration law of shear and compression characteristics of collapsible loess under dry-wet and freeze-thaw cycles
摘要
Abstract
A water conveyance open channel project in the northern Xinjiang region crosses a large area of collapsible loess.The mechanical properties of the collapsible loess have undergone severe degradation after years of exposure to rainfall,evaporation,and seasonal temperature fluctuations,making it highly susceptible to engineering phenomena such as channel foundation collapse and slope failure.To delve into the deterioration mechanism,direct shear,compression,and microscopic scanning tests were conducted on the collapsible loess under dry-wet & freeze-thaw cycles.The deterioration patterns of shear strength and compression properties,as well as their damage mechanisms,were analyzed at both macro and microscopic scales.The results of the study indicate(1)Straight shear test:with increasing the number of dry-wet-freeze-thaw cycles,the peak shear strength exhibits a three-stage trend:rapid decrease,decelerated rate of decrease,and eventual stabilization.The cohesion decreased exponentially,with the largest reduction occurring during the first cycle,and stabilizing after 5 cycles,reaching a degradation degree of 44.55％.The change in internal friction angle,which varied within 2.1°,was less affected by the wet-dry-freeze-thaw cycles,with a maximum degradation of 7.04％.(2)Compression test:the compression curve can be divided into two stages of elastic deformation and elastic-plastic deformation according to the consolidation yield stress σk,and σk shifts forward as the cycle times increase.The compression coefficient and compression index decreased exponentially or in a power function form with increasing cycle times,indicating reduced overall compressibility of the soil body.(3)Microstructure:through scanning electron microscope(SEM)analysis,under cycling,the number of large pores decreased while the number of medium and small pores increased,with the arrangement tending towards disorder.Large particles gradually transformed into medium and small particles,and their morphology tended to become rounded.Correlation analysis indicates that pore size and its angle are the main factors influencing shear strength.Pearson's correlation coefficient reveals that particle morphology and pore size have the greatest influence on compression indices.关键词
干湿-冻融循环/湿陷性黄土/剪切特性/压缩特性/微观结构Key words
dry-wet and freeze-thaw cycles/collapsible loess/shear characteristics/compression characteristics/microstructure分类
建筑与水利引用本文复制引用
樊培培,张凌凯,丁旭升..干湿-冻融循环条件下湿陷性黄土剪切及压缩特性的劣化规律[J].岩土力学,2024,45(7):2050-2060,11.基金项目
新疆维吾尔自治区杰出青年科学基金项目(No.2022D01E45) （No.2022D01E45）
2022年自治区重点研发任务专项(No.2022B03024-3) （No.2022B03024-3）
新疆维吾尔自治区水利科技专项(No.XSXJ-2023-22).This work was supported by the Outstanding Youth Science Fund Project of Xinjiang Uygur Autonomous Region(2022D01E45),Special Projects on Key R &D Tasks of the Autonomous Region in 2022(2022B03024-3),and Xinjiang Uygur Autonomous Region Water Conservancy Science and Technology Special(XSXJ-2023-22). （No.XSXJ-2023-22）
