Abstract: The talus is consists of boulders with various sizes, rock fragments and small amount of soils. It has a loose structure with large voids. The karst area has well developed rock caverns, pinnacles and rock fissures. The deep foundation type selection in the talus covered karst area is relative easy but the pile installation is critical to the construction schedule and the cost of the project. The rock percussion advancement with mud slurry for the borehole protection and other techniques is a proven success to this subsurface condition. The construction practice indicates that the manually controlled percussion drilling is a better choice for castinplace piles in talus covered karst areas.

Key words: Talus Formation, Karst Areas, Pile Type Selection, Percussion Drilling, Installation Techniques