Fundamental experiments on a reinforcement method using sheet pile wall for bridge pile foundations subjected to pile embedment reduction and numerical validation

Development of an effective countermeasure for existing bridge foundations subjected to the influence of riverbed excavation in Thailand is the main objective of this research. Due to the riverbed soil excavation for the utilization in construction works for many years, the level of riverbed of the Mae Nam Ping River has been considerably decreased, resulting in reduction of embedment lengths of piles for many bridge foundations. Erosion was not a cause of the lowering of the riverbed. Reductions of bearing capacity due to the lowering of riverbed soil is the main cause of bridge pile foundation settlements or collapses at present. In order to prevent the damages of existing bridge pile foundations caused by the riverbed soil excavation, a reinforcement method using sheet piles called “Sheet Pile Wall (SPW) reinforcement” is proposed in this paper. The proposed SPW reinforcement method consists of 2 simple steps without new additional piles or any modifications of existing structures. Firstly, sheet piles are constructed surrounding the existing problematic bridge pile foundation. Finally, the empty space inside the SPW is filled with sand or other porous materials such as crushed concrete. In order to investigate the performance of the proposed SPW reinforcement method, series of load tests on model pile foundations in dry sand were carried out. The experimental results show that the proposed SPW reinforcement method is very efficient and promising. Numerical simulation of an experiment using FEM was also carried out to get more insight into the mechanism of the SPW method and validate the proposed SPW method.