Experimental Study on the Influence of Substrate Properties on Rainfall Infiltration and Runoff from Ecological Slopes

Abstract

Rain is an important factor influencing the instability of ecological slopes. There is little research on the inherent quantitative influence of substrate properties on slope runoff and water infiltration to support accurate ecological slope protection design. In this paper, the influence of substrate characteristics on slope runoff and water infiltration is quantitatively analyzed by constructing large physical models with different substrate characteristics for artificial rainfall simulations. The experimental results showed that the cumulative runoff volume and slope runoff rate were positively correlated with the cement content and substrate thickness in a 4 h, 60 mm/h artificially simulated rainfall. Specifically, the cumulative runoff volume increased by 2.06% for every 1% increase in cement content, and the cumulative runoff volume increased by 3.93% for every 1 cm increase in substrate thickness. The substrate inhibited the advance of the wetting front, and at different slope locations, the transport rate of the wetting front exhibited a mid-slope > upslope. Moreover, the transport rate of the wetting front showed a non-linear relationship with time as a power function V = a·tb, with the cement content showing a linear relationship with parameters a and b, and the substrate thickness showing a non-linear relationship with parameters a and b. The cumulative infiltration and infiltration rate were negatively correlated with cement content and substrate thickness, as shown by a 2.2% decrease in cumulative infiltration for every 1% increase in cement content and a 4.73% decrease in cumulative infiltration for every 1 cm increase in substrate thickness.