摘要
为研究酸性环境对冻土地区路基强度与稳定性影响,对不同酸性浓度和不同冻融循环次数的红黏土试样进行常规三轴压缩试验(CU),分析酸蚀-冻融循环耦合作用下红黏土力学性质损伤劣化过程,并通过扫描电子显微镜(SEM)试验识别酸蚀-冻融循环耦合作用诱发红黏土微观结构演变与损伤机理。研究结果表明:红黏土与盐酸溶液反应后,应力-应变曲线呈现应变软化型,而随冻融循环次数增加,软化特性逐渐减弱;酸性溶液侵蚀土体结构,冻融循环作用使土体结构破坏和水分迁移,二者联合作用增大土体孔隙率,从而降低土体抗剪强度,通过对变形模量与冻融循环次数的非线性拟合,表明变形模量随冻融循环次数增加呈指数型劣化规律;初次冻融循环便会对红黏土抗剪强度、变形模量与黏聚力造成大幅度影响,但在5次冻融循环后,这些力学参数下降的幅度逐渐趋于稳定;酸蚀作用会降低红黏土凝聚力和内摩擦角,相同pH值时,随冻融循环次数增加,土体凝聚力持续减弱,而内摩擦角变化规律不明显;通过电镜扫描试验的分析表明酸蚀-冻融循环耦合作用破坏红黏土微观结构和改变颗粒间联结形式,增大土体内部孔隙与裂隙,降低土体的力学承载能力,从而劣化土体力学性能。研究成果可为受酸侵蚀的寒区工程项目提供参考。
In order to study the influence of acidic environment on the strength and stability of roadbeds in permafrost areas,conventional triaxial compression tests(CU)were conducted on red clay specimens with different acidic concentrations and different numbers of freeze-thaw cycles to analyze the damage deterioration process of mechanical properties of red clay under the coupling effect of acid-etching-freeze-thaw cycles,and identify the micro-structure evolution and damage mechanism of red clay induced by the coupling effect of acid-etching-freeze-thaw cycles through scanning electron microscopy(SEM)tests.The results show that the stress-strain curve of red clay reacting with hydrochloric acid solution shows a strain-softening type,and the softening characteristic gradually weakens with the increase of the number of freeze-thaw cycles.The acid solution erodes the soil structure,and the freeze-thaw cycle causes the destruction of soil structure and water migration.The combination of the acid solution and the freeze-thaw cycle increases the porosity of the soil,thus reducing the shear strength of the soil.The non-linear fitting of the deformation modulus with the number of freeze-thaw cycles shows that the deformation modulus shows an exponential deterioration rule with the increase of the number of freeze-thaw cycles.The shear strength,deformation modulus and cohesion of the red clay are greatly affected by the first freeze-thaw cycle,but after five cycles,the magnitude of the decrease in these mechanical parameters gradually stabilizes.The acid erosion decreases the cohesion and internal friction angle of red clay,and at the same pH,the cohesion of soil continues to weaken,while the change pattern of the internal friction angle is not obvious with the increase of freeze-thaw cycles.The analysis by electron microscopy scanning test shows that the coupling effect of acid-etching-freeze-thaw cycle destroys the micro-structure of red clay and changes the inter-particle association,increases the internal pores and fissures
作者
彭成
胡泽源
王东星
刘宵凌
莫彪
傅中志
PENG Cheng;HU Zeyuan;WANG Dongxing;LIU Xiaoing;MO Biao;FU Zhongzhi(Department of Civil Engineering,University of South China,Hengyang 421000,China;Nanjing Hydraulic Research Institute,Nanjing 210000,China;Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-Rock Dam of the Ministry of Water Resources,Nanjing 210000,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2023年第10期3738-3746,共9页
Journal of Railway Science and Engineering
基金
水利部土石坝破坏机理与防控技术重点实验室开放基金资助项目(YK319008)
国家自然科学基金面上项目(52079098)
国家自然科学基金青年基金资助项目(51708273)
湖南省教育厅项目(20C1608)。
关键词
酸蚀-冻融循环耦合作用
红黏土
常规三轴压缩试验
电镜扫描试验
抗剪强度
coupled acid-etching-freeze-thaw cycles
red clay
conventional triaxial compression test
electron microscopy scanning test
shear strength
