Numerical assessment of axial pile group response based on load test

Axial pile load tests are considered within the design procedure of most major construction projects that include pile foundations, aiming to determine both the ultimate bearing capacity and the pile stiffness at working load level. Commonly used pile spacings of 3-4 pile diameters between the test pile and the reaction piles cause significant interaction with drastic effect on to the load-settlement relationship. The objective of this paper is to evaluate the influence of this interaction on both bearing capacity and stiffness of single piles and pile groups. For this purpose, a back analysis of a pile load test was initially performed which facilitated the determination of the single pile response and the verification of the soil properties. Subsequently, a numerical analysis was carried out to establish load-displacement relationships for several different layouts of pile groups. Based on these non-linear analyses the effect of the interaction was quantified for both the pile load test and pile group layouts examined. (C) 2003 Elsevier Science Ltd. All rights reserved.