Microstructure and water-swelling mechanism of red-bed mudstone in the Xining region,Northeastern Tibetan Plateau  

作　　者：Huan Guan Yong Ren Sixiang Ling Xiyong Wu Tao Yu Xian Li Sen Wang Chunwei Sun 

机构地区：[1]School of Civil Engineering,Southwest Jiaotong University,Chengdu,610031,China [2]Faculty of Geosciences and Engineering,Southwest Jiaotong University,Chengdu,611756,China [3]Moe Key Laboratory of High-speed Railway Engineering,Southwest Jiaotong University,Chengdu,610031,China [4]Guangzhou Metro Design and Research Institute Co Ltd.,Guangzhou,510010,China [5]Chengdu City Construction Investment Group Co Ltd.,Chengdu,610036,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第7期2537-2551,共15页岩石力学与岩土工程学报（英文版）

基　　金：the funding support from National Natural Science Foundation of China(Grant No.42077271);Sichuan Science and Technology Program,China(Grant No.2023YFS0364);Chengdu Science and Technology Program(Grant No.2022-YF05-00340-SN).

摘　　要：This paper examines the effect of the microstructure and electrical conductivity(EC)on the swelling ratio and pressure in red-bed mudstone sampled from arid areas in the Xining region in the northeastern Tibetan Plateau.A series of laboratory tests,including swelling experiments,X-ray diffraction(XRD),and scanning electron microscope(SEM),was carried out for mechanical and microstructural analysis.The coupled influence of the EC and microstructural parameters on the expansion ratio and pressure was investigated,and the weight coefficients were discussed by the entropy weight method.The results revealed an increasing exponential trend in EC,and the maximum swelling speed occurred at an EC of approximately 10 μS/cm.In addition,a method for predicting the expansion potential is proposed based on the microstructure,and its reliability is verified by comparing with swelling experimental results.In addition,according to the image analysis results,the ranges of the change in the clay minerals content(CMC),the fractal dimension(FD),the average diameter(AD)of pores,and the plane porosity(PP)are 23.75%-53%,1.08-1.17,7.53-22.45 mm,and 0.62%-1.25%,respectively.Moreover,mudstone swelling is negatively correlated with the plane porosity,fractal dimension and average diameter and is linearly correlated with the clay mineral content.Furthermore,the weight values prove that the microstructural characteristics,including FD,AD,and PP,are the main factors influencing the expansion properties of red-bed mudstones in the Xining region.Based on the combination of macro and micro-analyses,a quantitative analysis of the swelling process of mudstones can provide a better reference for understanding the mechanism of expansion behavior.

关 键 词：MUDSTONES MICROSTRUCTURE Swelling characteristics Electrical conductivity(EC) Scanning electron microscope Water-swelling 

分 类 号：TU45[建筑科学—岩土工程]