Effects of inorganic salts on pore structure and permeability of undisturbed loess under dry and wet cycling conditions
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摘要: 【目的】干湿循环作用下无机盐溶液渗透对黄土体的结构强度和安全稳定性有着重要影响。该文研究目的是揭示干湿循环作用下无机盐对黄土孔隙结构及渗透性的影响。【方法】该研究以陕西省泾阳县南源的黄土为研究对象,通过室内试验,对不同干湿循环条件和不同浓度NaCl溶液入渗下原状黄土渗透性和孔隙结构的变化规律及其水土作用机制进行了系统分析。【结果】干湿循环削弱了原状黄土的渗透性,且随着干湿循环次数的增加,原状黄土的饱和渗透系数越小。NaCl溶液增强了原状黄土的渗透性,且随着NaCl入渗液浓度的增大,对渗透性的促进作用越明显。【结论】干湿循环促进了原状黄土表面裂隙发育,增加了土体中微孔的数量和面积比,使土体有效孔隙度减小,土体结构变得更加紧密。NaCl溶液的入渗促进了石膏等矿物的溶解作用,导致土体孔隙更加发育,渗透性增强。本研究加深了对干湿循环和无机盐溶液渗透的共同作用下黄土结构及渗透性变化规律的认识,为黄土地区的水土保持及工程建设提供科学支撑。Abstract: [Objective] The infiltration of inorganic salt solutions during dry and wet cycles exerts a significant influence on the structural strength and safety stability of loess masses. The aim of this research is to disclose the impact of inorganic salts on the pore structure and permeability of undisturbed loess under the effect of dry and wet cycles. [Methods] In order to fulfill this research objective, this study centered on the loess from the South Plateau in Jingyang County, Shaanxi Province. By employing laboratory experiments, this study systematically analyzed the variation law of the permeability and pore structure of undisturbed loess under diverse dry and wet cycling conditions and different concentrations of sodium chloride inorganic salt solution, as well as its mechanism of soil and water interaction. [Results] The findings indicated that dry and wet cycles diminished the permeability of undisturbed loess, and the saturated permeability coefficient of undisturbed loess decreased with the increment in the number of dry and wet cycles. The sodium chloride solution augmented the permeability of undisturbed loess, and the enhancement of permeability became more pronounced with the rise in the concentration of the sodium chloride infiltration solution. [Conclusion] Dry and wet cycles facilitated the development of fissures on the surface of undisturbed loess, augmenting the number and area ratio of micropores in the soil, thereby reducing the effective porosity of the soil mass and rendering the soil structure more compact. The infiltration of the sodium chloride solution promoted the dissolution of minerals such as gypsum and rock salt, leading to more developed soil pores and increased permeability. This study enriches the comprehension of the variation law of loess structure and permeability under the combined action of dry and wet cycles and inorganic salt solution infiltration, furnishing scientific support for soil and water conservation and engineering construction in loess regions.
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