Abstract: A Zhangjiagou fill slope in Shiyan with a height between 10.0 and 15.0m is unstable and deformed due to the influence of Huaxi Autumn in 2023 and other factors. According to the geological conditions, deformation characteristics and influencing factors on this fill slope, a genetic failure mode is summarized as follows: the fill load on the top of the slope and the forward slope structure provide basic conditions for the occurrence of the deformation and instability; the instability and deformation caused by the insufficient strength of the retaining structure and the foundation bearing capacity cannot be avoided; and the saturated weight and strength reduction of the fill soils caused by heavy rainfall are also the contributing factors of excessive deformation and instability. The excessive deformation of the fill slope development process has experienced three stages: initial stage, creep stage and failure stage. The stability analysis shows that the fill slope is in a stable state before the fill operation started; This slope is in a partial unstable and marginally stable state after the fill loading. The integrity of the support structure at the free face of the fill slope has been damaged. Considering the cost, difficulty, time and other factors, it is recommended to remove the fill and its support structure of the slope to eliminate the hidden factors of geological hazards.

Key words: Artificial Fill, Fill Slope, Landslide Deformation, Cause Analysis, Geologic Hazards