Evaluation of timber pile bearing capacity for transportation structures and cultural heritage building foundation retrofitting

As primary pile design methods are based on a database of loading tests on full-scale piles, there is a need to provide new results combined with modern ground investigation results for timber piles. Two experimental sites were established to test different species of timber piles in sandy gravel and clayey soils. An innovative instrumentation of piles with removable extensometer technique was adapted for use on these timber piles. This paper presents the characterization of the experimental site along with the properties of the timber piles, the instrumentation of each pile, the load test results and the parameters obtained for comparison of skin friction and tip resistance coefficients with those used in direct design methods. The originality and novelty of this study are to compare and evaluate local axial shaft friction for different wood species. These results can then be used as the basis for a reassessment of the bearing capacity of old foundation systems.