Mechanical properties and microstructural evolution of Malan loess with depth: Insights from multivariate statistical models

IF 6.1 1区农林科学 Q1 SOIL SCIENCE

Soil & Tillage Research Pub Date : 2025-03-20 DOI:10.1016/j.still.2025.106548

Xuanyu Gao , Wanli Xie , Kangze Yuan , Qiqi Liu

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Abstract

Malan loess is widely distributed on the Chinese Loess Plateau and poses great challenges to geotechnical, ecological, and agricultural practices due to its unique structure and collapsibility. It is essential to understand the evolution of these properties with depth to assess soil stability and reduce engineering risks in the area. This study investigates the mechanical properties and microstructural evolution of Malan loess with depth and employs multivariate statistical methods to explore their complex interrelationships. Oedometer-collapse tests reveal a 94.2 % reduction in collapsibility coefficient (δ_s) from 0.0722 at 1 m to 0.0042 at 9 m, indicating a significant reduction in collapsibility with increasing depth. According to the results of the direct shear test, it showed that the shear strength initially decreases and then increases due to the combined effect of the water content and dry density. Scanning electron microscopy (SEM) images reveal the densification of the loess structure, with changes in particle contact from point to face contact and the evolution from macropores to mesopores and small pores as depth increases. Quantitative analysis by Avzio showed a decrease of 61.5 % in macropores area and an increase of 62.5 % in small pores area. The results obtained by Pearson’s correlation analysis and random forest model showed that among these microstructural characteristics, the total pore area (%IncMSE = 22.77 %) is the most important factor influencing the collapsibility properties of loess and water content (%IncMSE = 17.72 %) acts a key role in controlling shear strength. Additionally, compared to traditional methods, the random forest model offers a more insightful understanding of nonlinear relationships and multifactorial coupling effects. These findings provide scientific guidance for geotechnical engineering in loess regions, aiding in risk mitigation and promoting sustainable construction.

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基于多元统计模型的马兰黄土深度力学特性与微观结构演化

马兰黄土在中国黄土高原分布广泛，由于其独特的结构和湿陷性，给岩土、生态和农业实践带来了巨大的挑战。了解这些特性随深度的变化对评估该地区的土壤稳定性和降低工程风险至关重要。本文对马兰黄土的力学特性和微观结构随深度的演变进行了研究，并采用多元统计方法探讨了它们之间的复杂相互关系。Oedometer-collapse试验表明，湿陷性系数（δs）从1 m处的0.0722降低到9 m处的0.0042，降低了94.2 %，表明湿陷性随深度的增加而显著降低。直剪试验结果表明，受含水率和干密度的共同作用，抗剪强度先减小后增大。扫描电镜（SEM）图像显示了黄土结构的致密化特征，颗粒接触随深度的增加从点接触到面接触，从大孔到中孔和小孔的演化。Avzio定量分析表明，大孔隙面积减少61.5 %，小孔隙面积增加62.5 %。Pearson相关分析和随机森林模型结果表明，在这些微观结构特征中，总孔隙面积（%IncMSE = 22.77 %）是影响黄土湿陷性的最重要因素，含水量（%IncMSE = 17.72 %）是控制抗剪强度的关键因素。此外，与传统方法相比，随机森林模型对非线性关系和多因子耦合效应提供了更深刻的理解。研究结果为黄土地区岩土工程提供了科学指导，有助于降低风险，促进可持续建设。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Soil & Tillage Research 农林科学-土壤科学

CiteScore

13.00

自引率

6.20%

发文量

266

审稿时长

5 months

期刊介绍： Soil & Tillage Research examines the physical, chemical and biological changes in the soil caused by tillage and field traffic. Manuscripts will be considered on aspects of soil science, physics, technology, mechanization and applied engineering for a sustainable balance among productivity, environmental quality and profitability. The following are examples of suitable topics within the scope of the journal of Soil and Tillage Research: The agricultural and biosystems engineering associated with tillage (including no-tillage, reduced-tillage and direct drilling), irrigation and drainage, crops and crop rotations, fertilization, rehabilitation of mine spoils and processes used to modify soils. Soil change effects on establishment and yield of crops, growth of plants and roots, structure and erosion of soil, cycling of carbon and nutrients, greenhouse gas emissions, leaching, runoff and other processes that affect environmental quality. Characterization or modeling of tillage and field traffic responses, soil, climate, or topographic effects, soil deformation processes, tillage tools, traction devices, energy requirements, economics, surface and subsurface water quality effects, tillage effects on weed, pest and disease control, and their interactions.