弱透水层低速非达西流咸水下移过程的模拟研究  

Numerical study on saltwater downward migration in aquitard as low velocity non-Darcy flow

作　　者：崔莉红[1] 成建梅[1] 路万里[1] 李敏敏[1] 

机构地区：[1]中国地质大学(武汉)环境学院,湖北武汉430074

出　　处：《水利学报》2014年第7期875-882,共8页Journal of Hydraulic Engineering

基　　金：国家重点基础研究发展计划973项目(2010CB42880203)

摘　　要：弱透水层以黏性土为主,其渗流通常表现出低速非达西特性。开采条件下,弱透水层中咸水下移问题是典型的渗流-固结-溶质运移耦合问题。本文以华北平原典型的"上咸下淡"含水层系统为研究对象,采用修正的多场耦合模型,研究了弱透水层中非达西渗流固结过程对咸水下移的影响。研究结果表明,非达西渗流不仅增加了黏性土层的固结时间,而且,在一定程度上,减缓了咸水下移速度。同时,非达西渗流条件下流速具有削峰拖尾特征,天然水力梯度越大,拖尾越不明显,而削峰始终存在。咸水下移前期,不考虑固结过程时其运移速度更快,而在中后期,情况相反。阻滞因子决定了弱透水层渗流固结过程对咸水下移的影响程度。Seepages in aquitard composed mainly of clay usually show the features of low-velocity non-Darcy flow. The downward migration of saltwater in aquitard is a typical problem of coupling fluid flow,soil consolidation and solute transport. This paper takes the example of a typical aquifer-aquitard system whose upper layer has salt water and lower layer has fresh water in the North China Plain. A modified coupling model has been used to study the influence of non-Darcy flow on vertically downward migration of saltwater. The results show that the non-Darcy flow not only increases the consolidation time,but also slows down saltwater migration. Moreover,the velocity distribution of non-Darcy flow has peak cutting and tailing effect. In early phase of saltwater migration,its velocity without considering consolidation is faster than that with considering consolidation. However,it is opposite in latter. The retardation factor shows prominent effects on how the Darcy and the non-Darcy flow in the aquitard influences the downward migration of saltwater.

关 键 词：弱透水层 非达西渗流 渗透固结 数值模拟 咸水下移 

分 类 号：P641.2[天文地球—地质矿产勘探]