Three-dimensional finite element analysis of piled rafts with energy piles

Over the last twenty years, the importance of environmentally friendly technologies in the field of construction has grown considerably. In this regard, energy piles are an innovative technology that combines the structural role of piles with that of a ground heat exchanger, through the inclusion of pipes carrying a heat exchanger fluid. Although it is common practice to cast the raft of a piled foundation directly on the ground, most of the available studies on energy piles have not been concerned with the implications that this entails. In this study, attempts have been made to fill this gap through a series of three-dimensional finite element simulations. This paper describes three dimensionless parameters, namely the raft to single isolated pile displacement ratio, the normalised differential displacement and the normalised thermally induced axial stress, which can be used to evaluate the overall performance of the foundation. The influence of the main mechanical parameters on the aforementioned dimensionless parameters is shown in graphical form and comparisons with conventional foundations are made.