Deviation rectification of a high-rise building with piled raft foundation: a case study

Deviation rectification of a high-rise building with a piled raft foundation was successfully carried out by vertically digging holes. Through site investigation and finite-element analyses of pile foundation settlement, the building tilt was attributed to shortening of the pile length, large post-construction settlement and cancellation of the setting of the post-cast strip of concrete between the main building and the skirt of an underground garage. A comprehensive rectification scheme was conducted, including drilling settlement-resisting micropiles on the side with a greater subsidence, cutting off the raft between the main building and the garage, vertically digging holes and disturbing soil on the side with less subsidence. When the rectified inclination reached the proposed value, the foundation was strengthened by the micropiles for settlement reduction and bearing capacity enhancement. During construction, close monitoring was carried out to guide dynamically the soil extraction operation and monitor building settlement. By analysing the monitoring data over time, the effectiveness of soil extraction for building rectification was verified, and the rectification mechanism of high-rise buildings supported on piled raft foundations was clarified. Finally, the rectification scheme was evaluated and discussed.