大孔隙参数对斜坡非均匀渗流与稳定性的影响

Influence of Macropore Parameters on Slope Non-uniform Flow and Stability

为揭示降雨条件下大孔隙参数对斜坡水分非均匀运移与稳定性的影响,基于两域模型与稳定系数场原理,建立降雨入渗下斜坡非均匀渗流与稳定性求解模型,并借助COMSOL Multiphysics多物理场有限元平台,编制相应的模型求解程序,通过大孔隙土柱降雨试验验证数值模型的合理性,对比均匀流与非均匀流条件下斜坡体积含水率和点稳定系数,分析大孔隙参数(大孔隙占比ω_(f)、两域导水系数之比μ、大孔隙经验参数r_(w))对斜坡渗流场及稳定系数场的影响规律。结果表明:相比不考虑大孔隙,考虑大孔隙时的基质域和大孔隙域表层体积含水率分别增长7.7%和降低5.1%,入渗深度分别增长83.3%和150.0%;边坡浅层失稳面积增大3.9%。基质域和大孔隙域入渗深度均随大孔隙占比ω_(f)的增大而减小;随着大孔隙域与基质域饱和渗透系数之比μ增大,两者入渗深度变化趋势相反,即μ越大,基质域入渗深度越小,大孔隙域反之;两者与经验参数r_(w)无显著关系。至降雨结束,基质域表层土体体积含水率已达最大值;大孔隙域则随着ω_(f)和μ的增大而增大,但几乎不受经验参数r_(w)的影响。非均匀流条件下,边坡水分交换沿着剖面从上往下分为负交换区、正交换区和无交换区,水分交换平衡深度与基质域入渗深度变化趋势一致;水分交换负交换区与正交换区的深度均存在一个峰值,并随大孔隙占比ω_(f)的增大而减小,随着μ和r_(w)的增大而增大。不同参数取值下,边坡均为浅层失稳破坏,ω_(f)和μ越大,失稳层深度越大,表层点稳定系数越小,因此大孔隙不利于边坡稳定。

To investigate the influence of macropore parameters on the non-uniform migration and stability of slopes under rainfall,a solution model was developed based on the two-domain model and the stability coefficient field principle.This model addressed non-uniform flow and slope stability under rainfall infiltration.Using the COMSOL Multiphysics finite element platform,a corresponding model solving program was created.The numerical results were validated through indoor rainfall tests on macropore soil columns.A comparison was made between slope volume water content and point stability coefficient under conditions of uniform and non-uniform flow.Subsequently,the impact of macropore parameters(namely,the proportion of macropore domainω_(f),the ratio of water conductivity between macropore and matrix domainμ,and the macropore empirical parameter r_(w))on slope seepage field and stability coefficient field was analyzed.The findings revealed that compared to scenarios without macropores,considering macropores led to a 7.7%increase in volume water content in the matrix domain and a 5.1%decrease in the macropore domain.Additionally,infiltration depth increased by 83.3%and 150.0%,respectively,and the shallow instability area of the slope expanded by 3.9%.Infiltration depth decreased with an increase inω_(f) for both the matrix and macropore domains.Conversely,with an in-crease inμ,infiltration depth decreased for the matrix domain and increased for the macropore domain.There was no significant relationship ob-served with the empirical parameter r_(w).At the end of the rainfall,volume water content in the matrix domain peaked,while the macropore do-main increased with higher values ofω_(f) andμ,showing minimal impact from the empirical parameter r_(w).Water exchange was categorized into negative exchange area,positive exchange area,and no exchange area along the profile.The equilibrium depth of water exchange aligned with the change in infiltration depth of the matrix domain.Both the negative and positive exchange areas exhibited peak values that decreased with higherω_(f) and increased with higherμand r_(w) values.Under varying parameter values,the slope experienced shallow instability failures.Higher values ofω_(f) andμcorresponded to deeper instability layers and lower point stability coefficients,indicating that macropores were detrimental to slope sta-bility.