Abstract: The uplift resistances of test piles and production pile for a deep excavation project in Rugao, Jiangsu Province, were compared throughout the static uplift loading tests and large uplift difference were identified between two piles. The uplift resistance value from the code suggested formula was much greater than that of the production pile inside the excavated area and this difference was exceed from the reasonable range due to the soil strata variation. The further evaluation concludes that the deep excavation reduces the normal pressures on the pile and unloading of the soil at the bottom of the excavation induces the rebound of the soil. As results from the soil rebound, an upward friction (similar to the negative friction) developed in the production pile was the major reason for the uplift resistance reduction.

Key words: Deep Excavation, Uplift Resistance of Single Piles, Unloading Rebound