Abstract: A detailed geotechnical investigation was performed on a landslide in the soil and rock mixture slope. The characterization of the landslide and the triggering factors were able to be identified. The investigation results concluded that two relatively independent landslides, namely, HP₁ and HP₂, existed in the system. Slide HP₁ had a slip surface along the interface of soil and rock, whereas, Slide HP₂ had a planar slip surface along the weak layer in the bedrock. The landslide mitigation program was therefore determined. Within the HP₁ and HP₂ slides, a combination of benching the slope, grid beam with ground anchors and drainage ditches was proposed. The large diameter drilled pier to resist the slide was also used in Slide HP2. The "m" method was able to be applied in the antislide drilled pier design.

Key words: Landslide Investigation, Characterization of Landslide, Landslide Mitigations, Analysis of the Drilled Pier for Sliding Resistant