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Durham University

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Publication details for Professor Ashraf Osman

da Silva, T.S. Haigh, S.K. Elshafie, M.Z.E.B. Jacobsz, S.W., Day, P.W. & Osman, A.S. (2019), Preparations for field testing for the performance validation of piled wind turbine foundations in expansive clays, in Kalumba, Denis eds, Proceedings of the 17th African Regional Conference on Soil Mechanics and Geotechnical Engineering. Cape Town, South Africa, ISSMGE, 661-666.

Author(s) from Durham


Field-testing of piles in an expansive clay is required for the validation of the design criteria for
wind turbine foundations in such soil profiles. The test programme includes lateral load tests to investigate the
horizontal stiffness of the soil and vertical plug pull-out tests to examine the axial capacity of pile-soil interface.
These tests will be conducted in both dry and wet conditions to study the range of expected responses of the
pile and evaluate how the changing soil moisture condition affects the pile behaviour. In addition, an instrumented
pile socketed into bedrock will be used to determine the strain induced in the pile due to soil heave as
the soil saturation levels increase. For the execution of these tests, a large open area with expansive clay of a
sufficient depth is required; a stable stratum below the clay is desirable for the socketing of the long piles. An
important component of the investigation is the characterisation of the expansive clay profile. A preliminary
site investigation has been carried out on the field-testing site which will be supported by further laboratory
testing. Details of the soil profile and site characterisation which will be used in the future analyses of the fieldtesting
results are presented.