Field investigation of the influence of basement excavation and dewatering on ground and structure responses

Abstract Although much research attention has been paid to ground and structure responses due to basement excavation, effects of dewatering during basement excavation on the deformation characteristics are not fully explored. A long and narrow basement with a final excavation depth of 14.5–17.0 m was heavily instrumented in soft clay. Basement excavation and dewatering induce substantially lateral wall movement at the pile toe of the retaining structure. The maximum lateral movement at the pile toe is up to 64.9% of the maximum lateral wall movement. Compared with the maximum ground surface settlement at the end of basement excavation, the maximum ground surface settlement is increased by 37% after casting concrete slab. Because of dewatering, the maximum lateral wall movement, vertical wall movement and ground settlement are up to 42.9%, 16.7% and 26.4% of the total movements, respectively. Moreover, building settlement due to dewatering is about 25–70% of the total building settlement. Dewatering and basement excavation-induced building settlement is in a range of 0.07% H to 0.15% H (excavation depth). Upon completion of casting concrete slab, the maximum building settlement is increased to 0.27% H. Thus, long-term effects of basement excavation on surrounding buildings should be taken into consideration.