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Hydrogeology Journal

, Volume 27, Issue 1, pp 171–182 | Cite as

Experimental study of water and salt migration in unsaturated loess

  • Gaochao Lin
  • Wenwu ChenEmail author
  • Peng Liu
  • Wei Liu
Paper
  • 91 Downloads

Abstract

Water and salt migration properties are important in many disciplines, including engineering construction, natural disaster prevention, agricultural irrigation and wastewater disposal. Relevant research into unsaturated loess caters to the development needs of the cities located on it. The objective of this study is to identify the water flow dynamics and consequent salt migration and redistribution (as well as their influence on microstructure alteration of the soil) during long-term seepage in unsaturated loess. In this experimental study, a long-term and one-dimensional seepage simulation test is conducted in a loess column. Probes are buried at different depths along the vertical profile to monitor and record the variations of volume water content and electrical conductivity. After the seepage test, soils at different depths are analyzed with different methods to make further investigation, including use of a pressure-plate apparatus to obtain soil-water characteristic curves, ion chromatography to determine the soluble salt components, and scanning electron microscopy to observe the microstructure changes. Good consistency between the different tests is obtained. Based on those results, the water and salt migration patterns and their influence on loess are analyzed and concluded.

Keywords

Unsaturated zone Loess Laboratory experiments/measurement Permeability characteristics Soluble salt 

Etude expérimentale de la migration de l’eau et du sel dans un loess insaturé

Résumé

Les propriétés de la migration de l’eau et du sel sont importantes dans beaucoup de disciplines, incluant le génie du bâtiment, la prévention des catastrophes naturelles, l’irrigation et le traitement des eaux usées. Une recherche appropriée sur le loess insaturé répond aux besoins de développement des villes situées au-dessus de lui. L’objectif de la présente étude est d’identifier la dynamique de l’écoulement de l’eau et la migration du sel qui en résulte et leur redistribution (aussi bien que leur influence sur l’altération de la microstructure du sol) au cours d’un ressuyage de longue durée dans un loess insaturé. Dans cette étude expérimentale, le test de simulation d’un ressuyage de longue durée et à une dimension est réalisé dans une colonne de loess. Des sondes sont implantées à différentes profondeurs le long du profil vertical pour contrôler et enregistrer les variations de la teneur en eau et la conductivité électrique du volume. Après le test de ressuyage, les sols sont analysés à différentes profondeurs par diverses méthodes dans le but de mener une investigation plus poussée, incluant l’utilisation d’un appareil à plaques pour obtenir des courbes caractéristiques de l’eau du sol, une chromatographie ionique pour déterminer les constituants du sel soluble et une microscopie électronique à balayage pour observer les changements de micro-stucture. Une bonne cohérence est obtenue entre les différents essais. Sur la base de ces résultats, les modèles de migration de l’eau et du sel et de leur impact sur le loess sont analysés et conclus.

Estudio experimental de la migración de agua y sal en el loess no saturado

Resumen

Las propiedades de migración de agua y sal son importantes en muchas disciplinas, incluidas la ingeniería de construcción, la prevención de desastres naturales, el riego agrícola y la eliminación de aguas residuales. La investigación relevante sobre el loess no saturado atiende las necesidades de desarrollo de las ciudades ubicadas en él. El objetivo de este estudio es identificar la dinámica del flujo de agua y la consecuente migración y redistribución de la sal (así como su influencia en la alteración de la microestructura del suelo) durante la filtración a largo plazo en loess no saturados. En este estudio experimental, se realiza una prueba de simulación de filtración a largo plazo y unidimensional en una columna loess. Las sondas son enterradas a diferentes profundidades a lo largo del perfil vertical para monitorear y registrar las variaciones de contenido de agua en volumen y la conductividad eléctrica. Después de la prueba de filtración, los suelos a diferentes profundidades se analizan con diferentes métodos para realizar investigaciones adicionales, incluyendo el uso de un aparato de placa de presión para obtener curvas características del agua del suelo, cromatografía iónica para determinar los componentes solubles de sal y microscopía electrónica de barrido para observar los cambios en la microestructura. Se obtiene una buena consistencia entre las diferentes pruebas. Sobre la base de esos resultados, se analizan y concluyen los patrones de migración de agua y sal y su influencia sobre el loess.

非饱和黄土中水和盐分运移试验研究

摘要

在许多学科中包括工程建设、自然灾害预防、农业灌溉和废水处理,水和盐分的运移特性非常重要。对非饱和黄土的相关研究服务于这些位于非饱和黄土上的城市发展需求。本研究的目的就是确定非饱和黄土中长期渗流期间水流动力学特征及其盐分运移及再分布(及其对土壤微观改变的影响)。这项试验研究中,进行了黄土土柱长期的和一维渗流模拟试验。沿垂直剖面不同深度埋设了探头用于监测和记录体积含水量和电导率的变化。渗流试验后,采用不同的方法包括使用压板装置获取土壤水特征曲线、使用离子色谱确定可溶盐成分以及使用扫描电子显微术观察微观结构变化等对不同深度的土壤进行了分析,以开展进一步的调查研究。获取的结果显示,不同的试验有非常好的一致性。在这些研究结果的基础上,分析和推断了水和盐分运移模式及其对黄土的影响。

Estudo experimental de migração de água e sal em loesse não saturado

Resumo

As propriedades da migração de sal e água são importantes em várias disciplinas, inclusive na engenharia de construções, prevenção de desastres naturais, irrigação agrícola e disposição de águas residuárias. Pesquisas relevantes de loesse não saturado serve para as necessidades de desenvolvimento de cidades localizadas sobre eles. O objetivo deste estudo é identificar as dinâmicas de escoamento de água e consequente migração salina e redistribuição (bem como sua influência na alteração microestrutural do solo) durante a infiltração de longo prazo em loesse não saturado. Neste estudo experimental, conduziu-se um teste de simulação de infiltração de longo prazo e unidimensional numa coluna de loesse. Sondas foram enterradas em diferentes profundidades ao longo de um perfil vertical para monitorar e registrar o conteúdo volumétrico de água e condutividade elétrica. Após o teste de infiltração, amostras de solo de diferentes profundidades foram analisadas com diferentes métodos visando investigações posteriores, incluindo o uso de câmaras pressão para obtenção das curvas características do solo, cromatografia de íons para determinar os componentes solúveis salinos, e microscopia eletrônica de varredura para observar as mudanças da microestrutura. Observou-se uma boa consistência entre os diferentes testes. Com base nesse resultados, os padrões migratórios de água e sal e suas influências em loesse foram analisados e concluídos.

Notes

Acknowledgements

We express our sincere gratitude to all those who helped us during the long-term experiments and the process of writing this thesis.

Funding information

We gratefully acknowledge the National Basic Research Program of China (973 Program) – Loess Water-Soil Interaction and Its Mutual Feedback Mechanism for Disasters (Grant Number: 2014CB744701), which provides a great scientific research platform and abundant financial support.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Gaochao Lin
    • 1
    • 2
  • Wenwu Chen
    • 1
    • 2
    Email author
  • Peng Liu
    • 1
    • 2
  • Wei Liu
    • 1
    • 2
  1. 1.Key Laboratory of Mechanics on Disaster and Environment in Western ChinaThe Ministry of Education of ChinaBeijingChina
  2. 2.School of Civil Engineering and MechanicsLanzhou UniversityLanzhouChina

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