Rainfall Physical Model Test of Loess Filling Slope Based on the NbS Structure

The increasing number of filling engineering slopes in the loess plateau area over three major projects, “building a city on leveled mountain” “consolidating the ditch and protecting the plateau” and “managing the ditch and creating land” are causing enormous potential geohazard. To provide a new solution for the treatment of the filling slopes in the loess plateau, a loess-paleosol layered self-stabilizing structure is introduced into the disaster prevention and control of loess filling slopes using quicklime and modified cellulose to improve the loess and a new water control structure of loess filling slopes is proposed based on the natural-based solution concept. Through physical model tests, the changes in the seepage field, stress field, and deformation field of filling slopes with or without water control structure are explored, and the final failure mode of slope instability is obtained. The results showed that: 1) compared to the remodeled loess, the improved loess has a better liquid limit, an increased plastic limit, an increased shear strength, a significantly decreased saturated coefficient of permeability, of which the modified cellulose improved loess coefficient of permeability decreased by 88.59% and the lime improved loess coefficient of permeability decreased by 95.18%, and a slower water migration speed in slopes with a water control structure. Besides, the low-permeability layer plays a good effect of water insulation; 2) the existence of anti-erosion surface layer improved the anti-erosion ability of the slope, and the erosion amount of the slope with water control structure was only 28.43% of that without water control structure; 3) the deformation and failure mode of the slope with water control structure was progressive shear slip instability, while the deformation and failure mode of the slope without water control structure was sudden collapse flow slip failure. The results of this study can provide a theoretical reference for ecological management and disaster prevention of filling slopes in the loess plateau.