变坡度变雨强下坡面流阻力特性时空分布

为了研究坡面薄层水流阻力特性规律，以室内人工降雨试验数据为基础，通过基于物理概念的水文数值模型试验，虚拟了150种工况，在大坡度范围（5°~55°）和大雨强范围（30~240 mm/h）内，以Darcy-Weisbach阻力系数为研究对象，研究阻力系数的时空分布规律，定量分析雨强和坡度对阻力系数的影响，从黏性底层厚度和能量的角度分析原因，根据试验结果回归得出考虑空间位置的阻力系数公式.研究结果表明：在坡度和雨强一定的前提下，在时间上，坡面阻力系数随着时间的增加呈减小趋势，在空间上，向下游出口处，阻力系数沿程递减；坡面流阻力系数受雨强影响显著，在一定坡度下，雨强越大，阻力系数越小；在一定雨强下，阻力系数与坡度基本呈正相关关系，且雨强越大，坡度对阻力系数的影响越弱.
Abstract: 150 numerical simulations were conducted based on indoor rainfall experiments using a soilflume, in order to analyze the resistance characteristic of sheet flow on slope. The slope gradientrange was 5°~55°, and the rainfall intensity was 30~240 mm/h. The spatio-temporal distribution of the resistance coefficient was analyzed taking the Darcy-Weisbach resistance coefficient as the object. The influence of rainfall intensity and slope on the resistance coefficient were quantified, and the reasons were discussed from the perspective of the depth of viscous sublayer and energy. A resistance coefficient formula which considered the spatial position was regressed. Results show that the resistance coefficient shows a decreasing trend in time, and a decreasing trend towards the downstream outlet in space, under certain rain intensity and slope gradient. Rainfall intensity significantly influences on the resistance coefficient. Under a certain slope gradient, the greater the rain intensity is the smaller the resistance coefficient is. Under a certain rainfall intensity, there is a positive correlation between the resistance coefficient and slope. The influence of slope gradient on the resistance coefficient decreases with rainfall intensity.