当前位置: X-MOL 学术Cold Reg. Sci. Technol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
The effect of microstructural evolution on the permeability of sandstone under freeze-thaw cycles
Cold Regions Science and Technology ( IF 4.1 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.coldregions.2020.103119
Xiao-Ping Zhou , Chang-Qing Li , Lun-Shi Zhou

Abstract Understanding the evolution of microstructures in freeze-thaw (FT) cycles is important to reveal the mechanisms of frost damage in porous rocks. This paper investigated the effect of microstructural evolution on the permeability of sandstone under FT cycles as well as the evolution pattern of microstructures. First, scanning electron microscopy (SEM) tests were carried out to investigate the evolution of sandstone microstructures at the same location under FT cycles. The experimental results showed that the FT cycles obviously caused the spalling of grains of the sample. Second, nuclear magnetic resonance (NMR) tests were conducted to investigate the evolution of the pore size distribution (PSD) and the permeability of sandstone samples under FT cycles. The experimental results showed that the FT cycles had obvious effects on pores with relaxation times varying from 1 ms to 100 ms. As the number of FT cycles increased, the percentage of nanoscale throats decreased, while the percentage of throats in the submicron and micron sizes increased. Third, the predictive model of permeability coefficient, dry density, porosity, surface porosity, surface fractal dimension, median pore size and median throat size was developed using a back propagation neural network (BPNN). Fourth, relative importance analysis of the above parameters was carried out, and the contribution of each parameter to the permeability coefficient of the sample was determined. Finally, the mechanism of FT damage was investigated. The present experimental results are helpful in improving the understanding of the leakage mechanisms of rock engineering in cold regions.

中文翻译:

冻融循环下微观结构演化对砂岩渗透率的影响

摘要 了解冻融 (FT) 循环中微观结构的演变对于揭示多孔岩石的冻害机制非常重要。本文研究了微观结构演化对 FT 循环下砂岩渗透率的影响以及微观结构的演化模式。首先,进行扫描电子显微镜 (SEM) 测试以研究在 FT 循环下相同位置的砂岩微观结构的演变。实验结果表明,FT循环明显引起了样品晶粒的剥落。其次,进行核磁共振 (NMR) 测试以研究孔径分布 (PSD) 的演变和砂岩样品在 FT 循环下的渗透率。实验结果表明,FT 循环对弛豫时间从 1 ms 到 100 ms 不等的孔隙有明显影响。随着 FT 循环次数的增加,纳米级喉道的百分比下降,而亚微米和微米级喉道的百分比增加。第三,利用反向传播神经网络(BPNN)开发了渗透系数、干密度、孔隙度、表面孔隙度、表面分形维数、中值孔径和中值喉道尺寸的预测模型。第四,对上述参数进行相对重要性分析,确定各参数对样品渗透系数的贡献。最后,研究了FT损伤的机制。
更新日期:2020-09-01
down
wechat
bug