A Case Study on the Lateral Movement of Pile Supported Bridge Abutment Constructed on Soft Soil

ABSTRACT The construction of bridge abutments on soft clay can induce significant lateral movement, often leading to structural distress as the expansion gap between the abutment and the embankment narrows. The Khulna–Mongla Port Rail Bridge experienced substantial lateral movement immediately after the full embankment was constructed. This study uses commercially available finite element (FE) software, PLAXIS 3D, and calibrated soil models, including the Soft Soil (SS) and soft soil creep (SSC) models, to investigate this phenomenon. Field monitoring data is used as a benchmark to compare the lateral displacement of the abutment with ground settlement. The study examines key design parameters affecting bridge stability, such as excess pore water pressure dissipation, bending moments in piles, and lateral and vertical displacements within the soft clay layer, through FE analysis. The results are consistent with published empirical design charts. The study also evaluates the effectiveness of a remedial measure involving the construction of a beam connected to the pile caps. The findings underscore the importance of addressing lateral movement, particularly in areas with organic soil layers, and demonstrate that the remedial measures significantly mitigate abutment lateral movement.