An analysis of the distance between surcharge load and existing bridged pile foundation in soft clay

The distance between surcharge load and existing bridged pile foundation is an important factor affecting the internal forces and displacements in piles. 3-D finite element models are set up to implore the behaviors of a pile foundation in a bridge of a high-speed railway line in China due to surcharge load. The calculated results are in good agreement with the field results. The distances between surcharge load and existing bridged pile foundation are varied to study the internal forces and horizontal displacements in piles. The results indicate that the larger the distance is, the smaller the internal forces and horizontal displacements in piles are. When the distance d is less than 4 times the depth of soft clay h, the horizontal displacements of pile groups decrease linearly quickly with an increase in d/h; while d is larger than 4 times h, the horizontal displacements of pile groups decrease slowly with an increase in d/h. The suitable distance between surcharge load and existing pile foundation is determined with the maximum permissible displacement of the upper structures under normal operating conditions.