Effects of Pile Extraction on Adjacent Bridge Structure in Soft Soil

While the effects of displacement piling on adjacent structures are well documented, limited data exist on the ground movements induced by the extraction of displacement or close-ended piles. This paper presents a case study involving significant movements observed in a newly constructed river bridge abutment, which occurred following the commencement of the extraction of adjacent temporary bridge piles. It is deemed that soil loss into the voids created by temporary pile removal is possibly the primary mechanism that caused the movements of the permanent bridge. Based on back-analysis of the survey monitoring data, the authors found that pile hole collapse mechanism may not be concentric in nature and the use of elastic cavity expansion solution could not adequately explain the preferential movements observed at the bridge abutment. Conversely, by adopting an asymmetric pile hole closure with elastic–plastic materials in the 3D finite element analysis (FEA), the authors were able to match all the measured horizontal movements at various locations of the permeant bridge abutment.