水位波动影响下的非稳定渗流问题研究  

Unsteady Seepage Problems Due to Water Level Fluctuation

作　　者：孙冬梅[1] 朱岳明[1] 张明进[2] 

机构地区：[1]河海大学水利水电工程学院,南京210098 [2]交通部天津水运工程科学研究所水工构造检测诊断与加固技术试验室,天津300456

出　　处：《天津大学学报》2007年第7期779-785,共7页Journal of Tianjin University(Science and Technology)

基　　金：国家自然科学基金重点资助项目(50539020;50539010);科技部中奥两国科技合作基金资助项目(VII.A.1);江苏省国际合作项目(BZ2003046)

摘　　要：非饱和土体孔隙中的水、气均遵守质量守恒定律和达西定律,根据多孔介质的多相流理论建立水-气二相流模型,模拟边坡土体在水位波动影响下水相和气相流体相互趋替的渗流行为.模型的求解采用效率较高的积分有限差分法进行空间离散,并编制了全隐式联立求解的计算程序,通过变换主要变量,实现了饱和(单相)与非饱和(二相)的相互转变,采用随时间变化的Dirichlet边界条件精确模拟水位波动时的变水头边界条件.同时分析了某土质边坡在水位波动影响下的孔压(孔隙水压力、孔隙气压力和毛细压力)及含水量变化情况.结果表明,由于气相的影响,孔隙水压力和毛细压力在非稳定渗流过程中存在显著差异,水位上升或下降时浸润线附近存在着含有封闭气体的准饱和区,该模型为定量研究准饱和区的渗流行为提供了有效途径.The flow of water and gas through unsaturated soils can be explained by a set of mass balance equations and Darcy＇s law. On the basis of muhiphase flow theory, a numerical model for water-air two-phase flow was proposed, to simulate the unsteady integral finite difference method seepage problems in bank was used in space discretization, slope induced by water level fluctuation. The and a fully implicit simuhaneous computation code was developed. By switching primary variables according to different phase states, the set of phase states （single-phase and two-phase） were taken into account. The time-dependent Dirichlet boundary condition was used to describe the variation of water head during water level fluctuation. The unsteady seepage problems of bank slope due to water level fluctuation, including variations of pore water pressure, pore air pressure, capillary pressure and water saturation were simulated numerically. The results indicate that due to the influence of gas phase, there is significant difference between negative pore water pressure and capillary pressure in unsaturated soils; there are quasi-saturated zones near the free table due to the fluctuation of water level, and the seepage state of the quasi-saturated zones can be calculated using the proposed water-air two-phase flow model.It provides an effective way to quantitatively study the seepage behavior of quasi-saturated soils.

关 键 词：非稳定渗流 水-气二相流 积分有限差分法 水位波动 准饱和土 

分 类 号：TV139.1[水利工程—水力学及河流动力学]