Updating reliability of pile groups with load tests considering spatially variable soils

This paper proposes a rigorous framework to update the reliability of pile groups based on load tests. The proposed approach enables the consideration of the spatial variability of soils, which is disregarded in previous studies. To achieve this, the random finite difference method (RFDM) is utilised to assess the group efficiency, individual pile capacities, and the correlation between individual pile capacities in spatially variable soils. Subsequently, Bayes' theorem is employed to update individual pile capacities based on load test results, taking into account the correlation between individual pile capacities. Finally, the reliability of pile groups is evaluated based on the group efficiency and updated individual pile capacities. An axially loaded pile group in undrained clays is utilised for demonstration. Results indicate that neglecting the spatial variability of soils may lead to unrealistic assessments of the reliability of pile groups. Specifically, in cases where all piles fail, the ignorance of spatial variability results in an overconservative design. Conversely, in cases where one or more piles pass, it leads to an unconservative design.