Abstract: Based on the loess high fill slope project in a certain section of Northwest China, this paper uses PLAXIS 3D software to establish a three-dimensional finite element model of the multistage high fill slope. The effects of changing fill, fill boundary, slope and unloading platform on slope stability were studied. According to the vertical displacement and horizontal displacement of the slope top, slope and foot, the distribution law of the most dangerous points at all levels and the trend of the whole slope deformation are analyzed. The results show that the cohesive force and internal friction angle of filling are the key factors affecting the stability of high fill slopes. Reducing the height of the step at the boundary between the fill and the undisturbed soil, deepening the step width, reducing the slope, and widening the unloading platform can improve the stability of the slope. During the construction of the lower slope, the vertical displacement changes rapidly and horizontal displacement changes slowly. The deformation is good after the construction. During the construction of the higher slope, the vertical and horizontal displacement abrupt change rapidly, and the distribution is not uniform. The consolidation settlement period is long and the deformation amount is large after the construction. It is necessary to strengthen the deformation monitoring of the higher slope after the construction. The research results determine the influence factors of stability, deformation trend and development law of loess high fill slope in Northwest China, and provides a scientific basis for further research on controlling the deformation of loess high fill slope.

Key words: loess, high fill, stability, deformation law