不同胶结度的饱和土壤孔隙尺度结构对地下水渗流特性的影响
Effects of Pore-scale Structure of Saturated Soil with Different Cementation Degrees on Groundwater Seepage Characteristic
侯玉松 1辛虎 1刘苏 1胡晓农 1苏靖芳 2吴吉春 3邢立亭1
作者信息
- 1. 济南大学水利与环境学院,济南 250022
- 2. 中国科学院南京土壤研究所,南京 210008
- 3. 南京大学地球科学与工程学院,南京 210023
- 折叠
摘要
饱和土壤中地下水渗流过程的研究在诸多领域具有重要意义,土壤孔隙尺度结构差异对地下水渗流特性有显著影响.土壤颗粒胶结度是土壤的基本属性之一,但是目前针对不同胶结度的土壤孔隙尺度结构差异对地下水渗流影响的研究尚少.采用整体重排算法构建不同胶结度的土壤介质孔隙尺度结构,基于此运用有限元软件模拟介质中地下水渗流过程开展相关研究.结果表明:土壤颗粒胶结度对饱和土壤中地下水渗流具有显著影响.随着胶结土壤颗粒百分数Pc从0增至60.20％,流场的变异函数增大了 70.15％(从1.233到2.098),即随着胶结度增大,流速空间非均质性显著增强.此外,沿地下水主要流动方向和垂直于主要流动方向上的流速概率密度分布函数均越来越发散.流速接近平均流速的区域减少,不流动区、优势流区同时显著增大.当Pc从0增至60.20％时,地下水中不流动区比例增大了 23倍(从2.06％到48.31％),而优势流区比例增大了将近9倍(从0.27％到2.41％).当平均流速不同时,渗流特征的以上变化趋势保持不变.此外,本研究发现不同胶结度介质间的孔隙尺度结构差异正是引起地下水渗流特性发生上述变化的内在原因.
Abstract
[Objective]The study of the groundwater seepage process in saturated soil media is of great importance in many fields,and the differences in the pore-scale structure of soil media have a significant effect on the properties of groundwater seepage.Soil grains cementation degree is one of the basic properties of soil media,but there are few studies on the effect of pore-scale structure differences of soil media with different cementation degrees on the properties of the groundwater seepage process.[Method]In this paper,related research is carried out based on pore-scale simulation.Soil media with different cementation degrees are constructed based on the global rearrangement algorithm,and the finite element software package is adopted to simulate the flow fields.[Result]The results showed that as the percentage of cemented soil particles Pc increased from 0 to 60.20％,the variation function of the flow field increased by 70.15％(from 1.233 to 2.098).Namely,the spatial heterogeneity of the flow velocity was significantly increased with increasing cementation degree.In addition,the probability density distribution of the flow velocity along the main groundwater flow direction and perpendicular to the main flow direction were increasingly divergent.The area where the flow velocity was close to the mean velocity decreased,and the stagnant regions and the preferential flow areas extend significantly at the same time.When Pc increased from 0 to 60.20％,the proportion of stagnant regions in the groundwater rose 23 times(from 2.06％to 48.31％),while the proportion of dominant flow areas increased nearly 9 times(from 0.27％to 2.41％).Also,when the average velocity of fluid was different,the above change trends of the seepage characteristics with rising cementation degrees remained the same.[Conclusion]These findings indicate that the cementation degree of soil particles has a significant effect on the characteristics of the groundwater flow field in saturated soil media.Besides,this paper found that the pore-scale structure differences of soil media with different cementation degrees are the internal reason for the above changes in groundwater seepage process characteristics.The dead-end pore structure formed by cementation,the irregular boundary of the cementation group,and the areas with poor connectivity upstream but connected to the flow area downstream often lead to the appearance of stagnant flow regions.With the increase of the stagnant regions,the fluid flows into the well-connected pores and flows rapidly along these pores.As a result,the dominant flow areas also increased with the rising cementation degree and even formed continuous dominant seepage channels.Under the influence of the simultaneous increase of stagnant regions and the dominant flow areas,the spatial heterogeneity of velocity was significantly enhanced.
关键词
地下水渗流特性/土壤颗粒/胶结度/孔隙尺度结构/数值模拟Key words
Groundwater seepage characteristic/Soil grains/Cementation degree/Pore-scale structure/Numerical simulation引用本文复制引用
基金项目
国家自然科学基金项目(42002257)
山东省自然科学基金项目(ZR2020QD123)
济南大学博士基金项目(XBS1911)
出版年
2024
国家科技期刊平台
NSTL
万方数据