Abstract: Structures in a rehabilitation and expansion project are pile supported and have a very strict total and differential settlement requirement on the foundations. The structures have large dimension and are not uniformly loaded. It is concluded that the post grout below the pile tips and at pile sides can improvement axial capacity and the stiffness of the castinplace reinforced concrete piles. The total and differential settlement reductions are achieved by the analysis the interactions among the supper structures, foundation soil and piles, and by using variable rigidity adjustment design. The pile foundation design is also optimized.

Key words: Pile Foundations, Post Grout, SoilStructure Interaction Analysis, Variable Rigidity Adjustment Design, Foundation Optimization