SUMMARYThe aim of this paper is to investigate the interaction between the piles in a group with a rigid head and correlate the response of a group of piles to that of a single pile. For this purpose, a computationally intensive study using 3-D nonlinear numerical analysis was carried out for different pile group arrangements in clayey soils. The responses of the groups of piles were compared with that of a single pile and the variation of the settlement amplification factor R a was then quantified. The influence of the number of piles, the spacing, and the settlement level on the group response is discussed. A previously proposed relationship for predicting the response of a pile group, based on its configuration and the response of a single pile, has been modified to extend its applicability for any pile spacing. The modified relationship provides a reasonable prediction for various group configurations in clayey soils.

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SUMMARYThe aim of this paper is to evaluate the influence of the interaction between the piles of a group fixed in a pile head on both bearing capacity and stiffness. For this purpose, numerical analyses were carried out to establish the load-displacement relationships for different 3*3 layouts of pile groups. The results are compared with those of the pile test carried out for the purposes of the project and the numerically established load-displacement curve of the single pile. Based on these non-linear analyses, the effect of the interaction was quantified for the pile group layouts examined, and was compared to proposed empirical relationships and reduction factors resulting from linear elastic analyses based on the principle of superposition. INTRODUCTIONThe effect of the interaction between the piles of a group under axial loading has been the subject of many researches during the past three decades. Based on the experience gained through these studies, empirical relationships were proposed to estimate the reduction factors on both, the bearing capacity and the stiffness of a group due to the interaction between the piles. Moreover, specific values for these factors have been proposed in tabular form resulting from simplified analyses based on elastic continuum analysis and the principle of superposition, Poulos and Davis /1 /, Poulos 121. An alternative approach is proposed by Lee 13/ in which the response of the single pile is simulated using the load-transfer (t-z) method, and the interaction between the piles is assessed using Mindlin's solution /4/. Another simplified approach providing a methodology for estimating the settlement of a pile group is the representation by an equivalent pier (Randolph /5/; Horikoshi and Randolph 161). Most of the above methods involve soil profile simplifications and other idealisations rendering them computer cost-effective with the drawback however of limited accuracy in many cases. Numerical methods such as Finite Element or Finite Difference Method, taking 27 Brought to you by | Western University Authenticated Download Date | 6/9/15 7:16 PM