Physical Model Test on the Interface of Loess Fill Slope

Abstract

The interface between the filling slope and the original slope is inevitable in the process of building a city in the loess area, which will affect the deformation and stability of the filling slope. In this paper, the loess fill slope of mountain excavation and city construction project in Yan’an City, China, is taken as the research object, and, based on field investigation and sampling, the effect of Loess Fill Slope Interface (LFSI) under rainfall is revealed by physical model test. The test samples were taken from a Loess Fill in Qilipu community, Yan’an, and three layers of sensors were arranged at the left and right interfaces of the original slope and the filled slope to monitor the water content, pore water pressure and deformation and failure characteristics during the experiment. The results show that ILFS is a rainfall dominant seepage channel, and the infiltration of rainfall along the interface lags behind. In addition, the variation laws of water content and pore water pressure at the interface between fill slope and original slope under rainfall are obtained. Finally, the failure process of loess fill slope under rainfall is summarized: local mud flow failure at the toe of the slope → erosion in the middle of the slope → crack initiation on the shoulder of the slope → local slip on the slope → crack propagation on the shoulder of the slope → shallow slip on the shoulder of the slope, and the instability mechanism of loess fill slope under rainfall is further revealed. The research results can provide theoretical and experimental reference for the protection of fill slopes in loess areas.