干湿循环下盐渍压实黄土湿陷性劣化机理研究  

MECHANISM OF COLLAPSIBILITY DEGRADATION OF SALINE COMPACTED LOESS UNDER WETTING AND DRYING CYCLES

作　　者：拓文鑫 倪万魁[1] 聂永鹏 TUO Wenxin;NI Wankui;NIE Yongpeng(College of Geological Engineering and Geomatics,Chang'an University,Xi'an 710061,China)

机构地区：[1]长安大学,地质与测绘学院,西安710061

出　　处：《工程地质学报》2024年第2期420-429,共10页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:41931285);陕西省重点研发计划项目(资助号:2019ZDLSF05-07)。

摘　　要：近年来黄土高原地区土壤盐渍化问题愈发严重,深入了解盐渍压实黄土在干湿循环作用下的湿陷性演化规律对当地填方工程安全至关重要。本文通过对不同干湿循环次数和硫酸钠(Na_(2)SO_(4))含量的压实黄土试样进行电镜扫描试验和室内湿陷试验,研究了盐渍压实黄土在干湿循环过程中的湿陷性劣化规律及其微观机理。结果表明:干湿和盐蚀的耦合作用使黄土结构趋于松散,造成湿陷系数增大,然而湿陷系数的增速随干湿次数增加而逐渐减小,表现出减速劣化特性,随含盐量增大而逐渐增大,呈现出加速劣化特性,且当含盐量大于0.5%时,盐蚀对湿陷性的劣化作用比干湿劣化作用更显著。最后,构建了同时考虑干湿循环次数和含盐量的经验模型,能较好描述盐渍压实黄土在干湿循环作用下的湿陷性演化规律。In recent years,soil salinization has become more and more serious in the Loess Plateau.It is very important to understand the collapsibility evolution of salinized compacted loess under the action of dry-wet cycles for the safety of local filling engineering.In this paper,the law of collapsibility degradation and its microscopic mechanism of saline-compacted loess during the dry-wet cycle were studied by scanning electron microscope and indoor collapsibility test on the compacted loess with different dry-wet cycle times and content.The results show that the coupling effect of dry-wet and salt erosion makes the loess structure tend to be loose,resulting in the increase of collapsibility coefficient.However,the coefficient of collapsibility growth decreases with the increase of the number of wet and dry cycles,showing slow degradation characteristics.It increases with the increase of salinity,presenting accelerated degradation characteristics.When the salt content is more than 0.5%,the degradation of the salt corrosion collapsibility effect is more significant than the dry and wet cycles.Finally,an empirical model considering both the number of dry-wet cycles and salt content was established to describe the collapsibility evolution of the saline-compacted loess under the dry-wet cycles.

关 键 词：压实黄土 干湿循环 盐蚀 湿陷性 解耦分析 

分 类 号：P642.3[天文地球—工程地质学]