Piled Rafts in Swelling or Consolidating Soils

Abstract

An analysis based on a simplified form of the boundary element method is used to analyze the interaction between a piled raft and a soil subjected to consolidation or expansive movements. The analysis allows for such factors as a nonhomogenous soil profile, pile‐soil slip, failure of the soil at the pile tip, and failure of the soil below raft elements. Via a relatively simple example, it is demonstrated that additional pile forces and movements are developed in the piled raft, as compared with the corresponding free‐standing pile group. In consolidating soils, raft‐soil contact can be lost and the load is then carried by the piles alone. In swelling soils, uplift pressures are developed on the raft, and tensile forces are induced in the piles. The use of piled rafts under these circumstances should generally be avoided.