Performance of Base Grouted Bored Piles in Specially Big Excavation Constructed Using Top-down Method

摘要

The foundation pit of Zhongsheng Commercial Centre Building was constructed using top-down method. The one-pile-supporting-on-column mode was adopted in the foundation excavation and basement construction, which means a higher capacity of piles to sustain the total load imposed by the building structure and the temporary constructing loads. Base grouting technique was used improve the bearing capacity of the conventional bored piles that are usually constructed using bentonite slurry. In order to verify the effectiveness of base grouting, static load tests were conducted on three base grouted piles and three conventional bored piles, those of 48m long and embedded into sand. The load-settlements, distribution of the skin friction and pile toe resistance are presented and compared. By not only increasing the pile end bearing and the basal stiffness but also increasing the skin friction, base grouting significantly improved the overall performance of the pile.