唐益群, 赵文强, 周洁. 2021: 冻结负温对海相淤泥质黏土变形特性影响的研究. 工程地质学报, 29(S1): 8-17. DOI: 10.13544/j.cnki.jeg.2021-0450
    引用本文: 唐益群, 赵文强, 周洁. 2021: 冻结负温对海相淤泥质黏土变形特性影响的研究. 工程地质学报, 29(S1): 8-17. DOI: 10.13544/j.cnki.jeg.2021-0450
    TANG Yiqun, ZHAO Wenqiang, ZHOU Jie. 2021: STUDY ON THE EFFECT OF COOLING TEMPERATURE ON DEFORMA-TION CHARACTERISTICS OF MARINE MUCK CLAY. JOURNAL OF ENGINEERING GEOLOGY, 29(S1): 8-17. DOI: 10.13544/j.cnki.jeg.2021-0450
    Citation: TANG Yiqun, ZHAO Wenqiang, ZHOU Jie. 2021: STUDY ON THE EFFECT OF COOLING TEMPERATURE ON DEFORMA-TION CHARACTERISTICS OF MARINE MUCK CLAY. JOURNAL OF ENGINEERING GEOLOGY, 29(S1): 8-17. DOI: 10.13544/j.cnki.jeg.2021-0450

    冻结负温对海相淤泥质黏土变形特性影响的研究

    STUDY ON THE EFFECT OF COOLING TEMPERATURE ON DEFORMA-TION CHARACTERISTICS OF MARINE MUCK CLAY

    • 摘要: 冻融后土体的渗透性、压缩性和固结特性是影响其冻结法施工工后变形速率和变形量的重要因素。本论文采用上海第四系滨海-浅海相淤泥质黏土,在-5~-25℃冻结负温下制备融土试样,通过含水率、密度、渗透和固结等一系列试验系统地揭示了冻结负温对沿海软黏土变形特性的影响;且结合不同冻结负温下冻融前后土体含水率、密度的差异,对软黏土竖向渗透系数、压缩系数等影响机理进行了探讨。结果表明:在封闭系统中经历一次冻融循环后,融土含水率、密度减小,渗透性、压缩性增大。随着冻结负温的降低,冻融作用对含水率的影响减弱,而对密度的影响增强。冻融作用引起的土体内部水分重分布和自由水相变是造成土体结构改变的根本原因,其结果导致土体冻融前后渗透性和压缩性的差异。融土压缩系数与初始孔隙比符合指数关系,故可通过室内试验结合拟合公式为变形量预测提供参数取值依据。融土垂向固结系数随冻结负温的降低呈线性减小,因此在变形量计算时应对冻结范围内土体进行温度分区。以上试验结果有助于推进冻结负温对软黏土变形特性的定量研究,为沿海软土地区冻结法应用提供依据。

       

      Abstract: The permeability, compressibility and consolidation characteristics of soil after freeze-thaw process are important factors that affect the deformation rate and amount of deformation after the artificial ground freezing construction. This paper aims to systematically reveal the effect of cooling temperature on deformation characteristics of coastal soft clayey soil, and carries out a series of tests include moisture content test, density test, penetration test and consolidation test on the undisturbed and frozen-thawed Shanghai Quaternary marine mucky clay at cooling temperatures of -5 to -25℃; combined with the changes in moisture content and density after freeze-thaw process at different cooling temperatures, it discusses the influence mechanism of vertical permeability coefficient and compression coefficient of soft clay. The results show that after undergoing single freeze-thaw cycle in a closed system, the moisture content and density of frozen-thawed soil decrease, while the freeze-thaw process enhances the permeability and compressibility of soil. As the cooling temperature decreases, the effect of freezing-thawing on the moisture content is weakened, while the effect on density is strengthened. The redistribution and phase conversion of water inside the samples caused by freezing-thawing are the fundamental reasons for the change of soil microstructure, which in turn leads to the differences in permeability and compressibility before freezing and after thawing. The compression coefficient and the initial void ratio of frozen-thawed soil are in an exponential relationship, suggesting that it is possible to provide the value of compression coefficient for deformation prediction by combining the laboratory test with the fitting formula. The vertical consolidation coefficient of frozen-thawed soil decreases linearly with the decrease of cooling temperature, hence the soil subjected to freezing-thawing should be temperature-zoned when calculating the amount of deformation. These findings help to promote the quantitative study of cooling temperature on the deformation characteristics of soft clayey soil, and provide some guidance for the application of artificial ground freezing method in coastal areas.

       

    /

    返回文章
    返回