Abstract: The uplift resistance of the underreamed drilled shafts is numerical evaluated in this paper. The results indicate that a large uplift is induced due to the rebound of the excavated area. The neutral point is near the bottom of the enlarge area. Under the excavation condition, the actual axial uplift load is far larger than the unexcavated condition, and the maximum uplift load is not at the top of the drilled shaft where the load is imposed. It is suggested that enough reinforcement is necessary to prevent the excessive tension in the shaft. The shaft resistance induced by excavation is large and cant be ignored. The enlarged bottom is taking about 37% uplift loading. The numerical studies verify the effectiveness of underreamed drilled shaft for the uplift resistance.

Key words: Underreamed Drilled Shafts, Uplift Loading, Deep Excavation, Numerical Simulation