长江科学院院报 ›› 2023, Vol. 40 ›› Issue (3): 124-130.DOI: 10.11988/ckyyb.20211060

• 岩土工程 • 上一篇    下一篇

单向冻结条件下硫酸钠盐渍土的冻结温度试验研究

任亚军1, 张卫兵1,2   

  1. 1.宁夏大学 土木与水利工程学院,银川 750021;
    2.宁夏大学 旱区现代农业水源高效利用教育部工程研究中心,银川 750021
  • 收稿日期:2021-10-11 修回日期:2021-12-25 出版日期:2023-03-01 发布日期:2023-03-28
  • 通讯作者: 张卫兵(1973-),男,宁夏银川人,教授,博士,主要从事土力学与基础工程方向的教学与研究。E-mail:zwb231@126.com
  • 作者简介:任亚军(1993-),男,山西长子人,硕士研究生,主要从事硫酸盐渍土机理研究。E-mail:15935696446@139.com
  • 基金资助:
    宁夏高等学校一流学科建设(国内一流建设学科)项目(NXYLXK2021A03);宁夏自然科学基金项目(2021AAC03067);宁夏大学研究生创新项目(GIP2021051)

Experimental Study on Freezing Temperature of Sodium Sulfate Saline Soil under Unidirectional Freezing Condition

REN Ya-jun1, ZHANG Wei-bing1,2   

  1. 1. School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China;
    2. EngineeringResearch Center of Ministry of Education on Efficient Utilization of Modern Agricultural Water Resourcesin Arid Regions, Ningxia University, Yinchuan 750021, China
  • Received:2021-10-11 Revised:2021-12-25 Online:2023-03-01 Published:2023-03-28

摘要: 硫酸钠盐渍土具有明显的随季节温度变化而发生土体结构改变的特性,给工程造成较大危害。为了研究单向冻结条件下硫酸钠盐渍土的冻结温度特性,在室内配制初始含水率分别为15%、17%、19%、21%,含盐量分别为0%、1%、2%、3%、5%的硫酸盐渍土试样,采用可控温冰柜进行单向冻结试验。结果表明:①同一土体,不同位置处冻结温度相同,但达到冻结温度所需时间存在略微差异。②初始含水率和含盐量对硫酸钠盐渍土冻结温度有很大的影响,当硫酸钠含盐量为1%和2%时,冻结温度随初始含水率的增加呈“先陡后缓”型变化趋势,并在最优初始含水率时达到最大值,之后冻结温度随初始含水率变化曲线趋于平缓;当含盐量较高(5%)时,冻结温度随初始含水率增加近似呈线性增加趋势。③硫酸钠盐渍土冻结温度随含盐量的增加而降低,且盐量为1%~2%时,不同初始含水率土体冻结温度及达到冻结温度所需时间随含盐量均呈“归一性”变化趋势。在计算硫酸钠盐渍土冻结温度时,应将硫酸钠溶液视为非理想稀溶液。在同一初始含水率条件下,对硫酸钠含盐量与冻结温度按三次多项式进行拟合吻合度较高。该研究成果可为硫酸盐渍土地区工程建设提供参考。

关键词: 硫酸钠盐渍土, 单向冻结, 冻结温度, 含水率, 含盐量

Abstract: The structure of sodium sulfate saline soil is prone to change with seasonal temperature, which is detrimental to projects. To study the freezing temperature characteristics of sodium sulfate saline soil under unidirectional freezing condition, we carried out unidirectional freezing test by using a controlled temperature freezer on indoor-prepared samples with initial moisture content of 15%, 17%, 19% and 21% and salt content of 0%, 1%, 2%, 3% and 5%. Results manifest that: 1) The time required to reach freezing temperature differs slightly at different locations in the same soil despite the same freezing temperature. 2) The initial moisture content and salinity of sulfate saline soil has a remarkable influence on freezing temperature. When the salinity of sodium sulfate is 1% and 2%, the freezing temperature first changes sharply but then gently with the increase of initial water content; the maximum freezing temperature is reached at optimal water content, and afterwards, the curve of freezing temperature tends to be flat with the change of initial water content. When salt content is high (5%), the freezing temperature rises linearly with the increase of initial water content. 3) The freezing temperature of sodium sulfate saline soil declines with the increase of salt content. When salt content is 1%-2%, the freezing temperature of soil with different water content and the time required to reach freezing temperature all presents a trend of “normalization”. Sodium sulfate solution should be regarded as a non-ideal dilute solution in the calculation of freezing temperature of sodium sulfate saline soil. In addition, at the same initial water content, the relationship between sodium sulfate salt content and freezing temperature can be well fitted by cubic polynomial.

Key words: sodium sulfate saline soil, unidirectional freezing, freezing temperature, moisture content, salt content

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