杜宇航 杨秀娟 樊恒辉 武雷杰 罗述伟

摘 要：钠盐累积对黄土的基本物理化学性质及工程性质有重要影响。以杨凌黄土为研究对象，通过添加不同质量的氯化钠溶液，人工制备钠盐含量分别为0.1%、0.3%、0.5%、1.0%和2.0%（质量分数）的钠盐土样，设置其含水率分别为13%、16%和19%，干密度分别为1.38、1.48、1.58、1.68 g/cm3，进行相对密度、酸碱度、击实、渗透、直剪及扫描电镜试验，分析钠盐含量、干密度和含水率对黄土基本性质的影响。结果表明：随着氯化钠含量的增加，土样相对密度、最优含水率及渗透系数逐渐减小，扫描电镜显示颗粒团聚、孔隙变大现象加剧，黏聚力总体呈现先增大后减小的趋势，在13%和16%含水率时，内摩擦角在30°至40°之间波动，但在含水率较大时呈现W形。研究结果可为盐渍化过程中黄土地区的工程建设提供借鉴。

关键词：环境岩土工程;盐渍土;黄土;钠盐含量;工程性质

中图分类号：TV16;TV411 文献标志码：A

doi：10.3969/j.issn.1000-1379.2020.02.029

Abstract：The accumulation of sodium salt has an important influence to the basic physical and chemical properties and engineering properties of loess. Taking Yangling loess as the research object， the sodium salt samples with the salt content of 0.1%， 0.3%， 0.5%， 1.0% and 2.0% （mass fraction） were artificially prepared by adding different quality sodium chloride solutions. The water content was 13%， 16% and 19%， and the dry density was 1.38 g/cm3， 1.48 g/cm3， 1.58 g/cm3and 1.68 g/cm3， respectively. The relative density， pH， compaction and penetration of soil particles were respectively carried out. Direct shear and scanning electron microscopy experiments were carried out to analyze the effects of sodium salt content， dry density and water content on the basic properties of loess. The results show that with the increase of sodium chloride content， the relative density of soil particles， the optimum water content and the permeability coefficient decrease gradually. Scanning electron microscopy show an increase in particle agglomeration and pore enlargement. The cohesive force generally increases first and then decreases. When the water content is 13% and 16%， the internal friction angle fluctuates between 30° and 40°， but exhibits “W” shape when the water content is high. The research results provide reference for the construction of the loess area during the salinization process.

Key words： environmental geotechnical engineering; saline soil; loess; sodium salt content; engineering property

盐渍土是盐土、碱土及各种盐化、碱化土的总称，遇水后发生溶陷、盐胀等现象，为工程建设及农业生产带来严重危害[1-2]。我国西北黄土地区地处干旱半干旱区域，蒸发过量、灌溉不利等因素导致土体中盐分含量逐渐增加、土体盐渍化程度严重。

国内外科研人员针对盐渍土的工程性质开展了广泛研究，并取得了不少成果[3-4]。谌文武等[5-6]对氯盐和硫酸盐的液塑限与界限含水率的研究认为，盐会导致黏粒含量变化，从而对液塑限产生影响，同时在含水率较小的情况下，土体强度随钠盐含量增加而……