Assessments of dimensionless pile stiffness for embedded piled raft foundations in soft clays under vertical loads

Abstract

Three-dimensional finite element analysis has been widely used in foundation design. For the efficiency of computations, simplified analysis treating the soils by series of springs were suggested in many design practice. For piled raft foundation, the coefficients of subgrade reactions and the pile stiffness are thus important to the design analysis. This paper intends to discuss the values of coefficients of pile reactions and/or pile stiffness for the embedded piled raft foundations in soft clays subjected to vertical uniform loads. Dimensionless pile displacements, pile reactions, and coefficient of pile reactions were suggested. Their correlations with the ratio of foundation embedment depth to raft size, the slenderness ratio of pile, and the ratio of pile-to-pile spacing distance to pile diameter were examined. Finally the optimized correlation diagrams were reported while a simple modelling was able to verify the suggestion.