Abstract: Guilin is located in a typical Karst terrain. The probe boring practice in the area is one hole for each castinpace pile. Potential safety hazard might exist for this general practice since the accurate geological information below the large diameter pile tip is still difficult to obtain. In the foundation construction project of a residential community, which large diameter castinplace piles are utilized, the number of probe holes at each pile location are optimized. The spacing of the probe holes is determined by the diameter of the proposed pile and the tip elevation is determined based on the most unfavorable conditions revealed by the probe holes. The construction records and pile coring results verified that the investigation was very close to the actual construction conditions. The coring results also indicate that there are no rock cavities and broken rock mass underlying the pile.

Key words: Guilin, Large Diameter CastinPlace Concrete Piles, Probe Holes, Geotechnical Investigations, Optimization Design