三维地形条件下雨水入渗与地表径流耦合分析

Coupled analysis of rainwater infiltration and surface runoffunder three-dimensional topographic conditions

为定量表述降雨发生后不同时刻下三维边坡土壤水分的分布和变化规律,基于有限体积法建立了雨水入渗与地表径流耦合模型.耦合模型分别采用二维不可压缩Navier-Stokes方程和三维非线性Richards方程作为地表径流和地下水渗流的控制方程,在复杂三维地形条件下具有较强的适用性.对一处实际工程的分析结果表明:在三维地形因素的控制下,降雨引发的地表径流主要汇集于总体上自高向低流动的优势径流途径,并对降雨强度的变化产生延迟响应;在地表径流作用下,地表积水深度在局部空间上呈现出地势低洼处远大于地势较高处的显著不均匀分布,并且这种不均匀性随时间不断加剧;地表积水汇集产生的高水力梯度导致低洼处的雨水入渗更为强烈且持久.研究表明,考虑三维地形因素的雨水入渗与地表径流耦合模型能够为实际工程中边坡稳定性分析提供准确合理的数据支撑.

To quantitatively describe the distribution and variation of soil moisture in the three-dimensional(3D)slope at different moments after rainfall,a coupled model of rainwater infiltration and surface runoff was established based on the finite volume method.The two-dimensional incompressible Navier-Stokes equation and 3D nonlinear Richards equation were used as the governing equations for surface runoff and groundwater seepage,respectively.The coupled model has superior applicability under complex 3D topographic conditions.The analysis results of an actual project indicate that,under the control of 3D topographic factors,surface runoff caused by rainfall mainly converges in the dominant runoff pathway that flows from high to low overall,and has a delayed response to changes in rainfall intensity.Under the influence of surface runoff,the depth of surface water accumulation shows a significant uneven distribution in local space,with much greater accumulation in low-lying areas compared with high elevations,and this non-uniformity intensifies over time.High hydraulic gradient generated by the accumulation of surface water causes more intense and persistent infiltration in low-lying areas.Research indicates that the coupled model of rainwater infiltration and surface runoff considering 3D topographic factors can provide accurate and reasonable data support for the slope stability analysis in practical engineering.