摘要
为探究冻融循环作用下含Na_(2)SO_(4)盐原状黄土宏观强度与微观结构关联机制,对黄土试样进行不同次数的冻融循环试验、不同Na_(2)SO_(4)盐含量的渗透试验、微观试验(扫描电子显微镜试验)及宏观试验(固结不排水三轴剪切试验),运用灰色关联分析法确定不同盐浓度和不同冻融循环次数下试样的抗剪强度指数和微观组织参数之间的相关性,从宏-微观角度分析其强度指标变化规律和微观孔隙的损伤变化规律。研究结果表明:(1)含Na_(2)SO_(4)盐量的变化和冻融循环会引起土壤中孔隙所占比例和面积的重新分配。表现为随含盐量增加,大孔隙向中小孔隙转变;随冻融循环次数增加,中小孔隙向大孔隙转变。(2)在冻融作用下,随着冻融循环次数或含盐量的增加,土体强度、黏聚力、内摩擦角明显降低;当冻融循环次数增加到5次以上时,土体内部扰动趋于稳定。(3)根据灰色关联法分析得到,颗粒分布的改变对黏聚力变化的影响权重最大,土颗粒面积-周长的变化对内摩擦角具有最大的影响;在冻融循环过程中,颗粒的微观结构特性与内摩擦角的相关程度较高,与黏聚力的相关程度较低;随着冻融循环次数的增加,面积-周长法分形维数对黏聚力和内摩擦角的影响最大;微观结构特性参数中颗粒形态起主导作用,对黄土的抗剪强度影响最大。
To explore the correlation mechanism between the macroscopic strength and microscopic structure of undisturbed loess containing Na_(2)SO_(4) salt under freeze-thaw cycles,loess samples were subjected to different freeze-thaw cycle tests,permeability tests with different Na_(2)SO_(4) salt contents,microscopic tests(scanning electron microscope tests),and macroscopic tests(consolidated-undrained shear tests).The grey correlation analysis method was used to determine the correlation between the shear strength index and microscopic tissue parameters of the samples under different salt concentrations and freeze-thaw cycle times.The strength index changes and microscopic pore damage changes were analyzed from a macro-micro perspective.The research results indicate that:1)Changes in Na_(2)SO_(4) salt content and freeze-thaw cycles can cause a redistribution of the proportion and area of pores in the soil.As the salt content increases,large pores transform into small and medium-sized pores.As the number of freeze-thaw cycles increases,small and medium-sized pores transform into large pores.2)Under freeze-thaw conditions,as the number of freeze-thaw cycles or salt content increases,the strength,cohesion,and internal friction angle of the soil significantly decrease.When the number of freeze-thaw cycles increases to 5 or more,the internal disturbance of the soil tends to stabilize.3)According to the grey correlation analysis,the change in particle distribution has the greatest impact weight on the change in cohesion,and the change in soil particle area circumference has the greatest impact on the internal friction angle.During the freeze-thaw cycle,the correlation between the microstructure characteristics of particles and the internal friction angle is high,while the correlation between cohesion is low.As the number of freeze-thaw cycles increases,the fractal dimension of the area perimeter method has the greatest impact on cohesion and internal friction angle.The particle morphology plays a dominant role in the microstructural characteristic parameters and has the greatest impact on the shear strength of loess.
作者
郅彬
魏园钧
王番
张茜
刘存利
任会明
ZHI Bin;WEI Yuan-jun;WANG Pan;ZHANG Qian;LIU Cun-li;REN Hui-ming(School of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an,Shaanxi 710054,China;Shaanxi Academy of Building Sciences Co.,Ltd,Xi’an,Shaanxi 710082,China)
出处
《岩土力学》
北大核心
2025年第S1期106-120,共15页
Rock and Soil Mechanics
基金
国家自然科学基金青年科学基金项目(No.42401160)
陕西省自然科学基金一般项目-青年基金(No.2024JC-YBQN-0258)
陕西省青年人才项目
关键词
微观结构
易溶盐
冻融循环
黄土
microstructure
soluble salt
freeze-thaw cycle
loess
