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Experimental study of the microstructure of loess on its macroscopic geotechnical properties of the Baozhong railway subgrade in Ningxia, China
Bulletin of Engineering Geology and the Environment ( IF 4.2 ) Pub Date : 2020-06-10 , DOI: 10.1007/s10064-020-01816-9
Zhao Meng , Chen Liyi , Wang Shanyong , Wu Honggang

Loess is found all over the world, accounting for about 10 % of the world’s total land area. This soil exhibits a distinctive behavior that is related to their formation history, mineralogy, and microstructure, which can cause serious geotechnical engineering problems. This paper presents the microstructural evolution of the subgrade loess of the Baozhong railway in Guyuan. Particularly, the collapse potential, shear behavior, and the influence of microstructure on them are experimentally studied. The results reveal that the top loess contains more clay content, and the grains with a size of 1–20 μm are significantly more than those of the middle loess and the bottom loess. These particles usually have the effect of combining quartz, feldspar, and other particles. In addition, the macroscopic mechanical properties of top loess are more influenced by intergrains cementation bonds and are more sensitive to water. As a comparison, the middle and bottom loess are more influenced by its loose interstructure and are more sensitive to compression. Based on the analysis of microstructure, a cyclic process model which link the pore change and particle packing is proposed. It is demonstrated that the particle packing is closely related to the change of pores. While the pores decrease to a minimum, the particle packing changes to a bridged random close packing. This mechanism can be used to explain the uneven settlement of the Baozhong railway subgrade in Ningxia.



中文翻译:

宁夏宝中铁路路基黄土微观结构宏观工程试验研究

黄土遍布世界各地,约占世界总土地面积的10%。这种土壤表现出与它们的形成历史,矿物学和微观结构有关的独特行为,这可能会导致严重的岩土工程问题。本文介绍了固原宝中铁路路基黄土的微观结构演变。特别是,实验研究了崩塌势,剪切行为以及微观结构对其的影响。结果表明,顶部黄土中粘土含量更高,尺寸为1–20μm的颗粒明显大于中部黄土和底部黄土。这些颗粒通常具有结合石英,长石和其他颗粒的作用。此外,黄土的宏观力学性能受颗粒间胶结作用的影响更大,对水更敏感。相比之下,中,下部黄土受其松散的组织结构影响更大,对压缩更敏感。在微观结构分析的基础上,提出了一种将孔隙变化与颗粒堆积联系起来的循环过程模型。结果表明,颗粒堆积与孔的变化密切相关。当孔减少到最小时,颗粒堆积变为桥接的随机紧密堆积。这种机制可以用来解释宁夏宝中铁路路基的不均匀沉降。中黄土和下部黄土受其松散的组织结构影响更大,对压缩更敏感。在微观结构分析的基础上,提出了一种将孔隙变化与颗粒堆积联系起来的循环过程模型。结果表明,颗粒堆积与孔的变化密切相关。当孔减少到最小时,颗粒堆积变为桥接的随机紧密堆积。这种机制可以用来解释宁夏宝中铁路路基的不均匀沉降。中黄土和下部黄土受其松散的组织结构影响更大,对压缩更敏感。在微观结构分析的基础上,提出了一种将孔隙变化与颗粒堆积联系起来的循环过程模型。结果表明,颗粒堆积与孔的变化密切相关。当孔减少到最小时,颗粒堆积变为桥接的随机紧密堆积。这种机制可以用来解释宁夏宝中铁路路基的不均匀沉降。粒子堆积变为桥接的随机紧密堆积。这种机制可以用来解释宁夏宝中铁路路基的不均匀沉降。粒子堆积变为桥接的随机紧密堆积。这种机制可以用来解释宁夏宝中铁路路基的不均匀沉降。

更新日期:2020-06-10
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