School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.
In a group of installed piles, the stresses applied from one pile to soil may have overlaps with another pile which leads to the changes in bearing capacity and settlement of each individual pile. In order to predict the performance of those piles, interaction coecients, based on elasticity theory proposed by Mindlin, are widely applied. In this paper, the eect of soil relative density and also toe condition on the interaction between two similar piles in sandy soil is presented using centrifuge modeling. To achieve this objective, 22 tests have been conducted to investigate the eect of soil relative density and another 11 tests were performed to study the contribution of pile toe and shaft in the interactions. The results showed that the value of soil relative density has an important role in the coecient of interaction which has not been considered in previously reported correlations. For this reason a modication has been proposed for the Randolph and Wroth equation to consider soil relative density. Accuracy prediction of the new modelwas compared with the Randolph and Wroth equation with the aid of dierent statistical parameters. This comparison indicated the superiority of the proposed model over previous methods.