A Calculation of Behavior of Underpinning Pile Subject to Excavation of Deep Foundation Pit

Abstract:

Behavior of underpinning pile foundation is affected by unloading and rebound subject to deep excavation.Based on residual stress method and Mindlin solution,an analysis was made of the rebound of rigid pile and the distribution of shaft resistance under the condition of displacement compatibility and pile’s force balance when pile’s self weight was neglected.Analysis results indicate that pile’s displacement decreases as its length and diameter increase.Changes of pile’s diameter have little impact on the depth of neutral point and the distribution pattern of shaft resistance.The neutral point is becoming lower as pile length is increasing and the same with the rebound and recompression modulus.The rebound of underpinning pile increases as excavation depth increases and becomes gradual when pile length is relatively longer.Pile’s displacement decreases and then reaches a certain value as the modulus of soil rebound and recompression increases.