Deep excavations release stresses in the earth and redistribute these stresses causing deformation. The pressure loss due to excavation may result in a base instability, where the soil flow beneath the sheeting into the excavation, producing a rise in the base elevation commonly termed as heave. The heave can lead the foundation piles casted before excavation to floating and being in tension, and even induce the tensile failure of pile in severe case. The characters of foundation piles in different excavation conditions, different location have been analyzed by a case study. The calculation results show that the deeper excavation, the larger vertical force acted on the foundation pile and the heave could induce the tensile failure of the foundation piles. So it is recommended that the tensile capacity of the foundation piles should be verified when the excavation is very deep.