Abstract: Under a “50-year return period” storm, most of the original anti-uplift ground anchors of a project in Shandong were pulled out. Resulting in a significant uplift of the underground garage structure, multiple locations found cracks at the raft foundations, and several hollow bulges were also observed at the raft foundations. There is an urgent need to repair the underground garage. In response to such hazards, the project adopts a comprehensive mitigation plan that combining “anti-buoyancy grouted ground anchor + drainage and water pressure relief system+pier cap grouting+crack repair”. Finally, the good effect of the “restoration of anti-buoyancy axial resistance+anti-buoyancy reservation for water releasing and pore pressure relief +filling of gaps under the raft foundation+ repairing cracks on the raft foundation” was achieved. Not only did it effectively solve the problems of anti-buoyancy failure of the original structure and raft foundation separation, but it also maximizes the repair of the original damage of the raft foundation. After the mitigation, no further cracking development was observed at the raft foundation, and the ground was flat without water seepage. The mitigation effect was satisfactory. This comprehensive mitigation plan complements and improves each other, and the reinforcement effect is significant. This provides a new approach for similar engineering design and has achieved significant economic and social benefits.

Key words: Anti-Buoyancy Grouted Ground Anchor, Water Level Reduction and Pressure Relief System, Pier Cap Injection, Crack Repair, Comprehensive Mitigations