Predictions and Performance of Uplift Piles in Soft Ground

摘要

Predictions and performance of uplift piles embedded in soft ground have recently received much attention due to extensive use of uplift piles in underground structures. Shanghai World Expo 500kV Underground Transformer Substation and Shanghai Hongqiao Comprehensive Transportation Hub are typical examples. Both uniform-section piles with side-grouting and enlarged base piles have been extensively used in the engineering practice. Despite of their extensive applications, theoretical and laboratory experimental studies have lagged far behind engineering practice. In this paper, a comprehensive study on three key issues faced is presented, including the predictions of the ultimate bearing capacity of base enlarged base piles, loaddisplacement responses of side-grouted piles, and bearing capacity loss of uplift piles after deep excavation. Centrifuge tests were conducted to further demonstrate the performance of side-grouted piles and enlarged base piles before and after deep excavation. Present theoretical and experimental studies have provided a deep understanding in the design issues of uplift piles used in soft ground.