The research will be divided into four work packages: WP1 field testing, WP2 Centrifuge models, WP3 Soil testing and WP4 Numerical analysis. More details on each section can be found below.
WP1 – Field testing of foundations
WP leader – Dr Elshafie, University of Cambridge
Field tests are vital to establish the actual performance of piles under loading and to validate the assumptions made during initial design; this is particularly relevant when dealing with expansive and unsaturated soils as found in sub-Saharan countries.
WP2 – Centrifuge testing of foundations
WP leader – Prof Jacobsz, University of Pretoria, South Africa
The series of field tests to be carried out are vital to understand the behaviour of wind turbine foundations in these soils but there is, in these tests, limited control over the properties of the soils on which the tests are carried out; one has to work with the natural in situ materials underlying the site. The behaviour of a foundation system observed in such field tests could therefore be site specific. It is therefore often difficult to extrapolate results from such testing to other ground conditions. Therefore, it is attractive to carry out additional investigations using small scale physical models in which a range of ground conditions, over which the researcher has complete control, can be carried out. The model study will be carried out in a geotechnical centrifuge to increase stresses to ensure that model behaviour is representative of the full scale.
Eg. See the pictures from the first centrifuge testing here.
WP3 – Laboratory Soil testing
WP leader – Dr Biscontin, University of Cambridge
This work will provide mechanical & hydraulic property data that will feed into the centrifuge and numerical modelling. Samples will be transferred to the University of Cambridge for laboratory analysis. Analysis will include producing soil water retention curves using the tensiometer method followed by mechanical testing to include (but not be restricted to) monotonic and cyclic triaxial and cyclic direct shear testing.
WP4 – Numerical Analysis
WP leader – Dr Osman, Durham University
Advanced numerical tools will be developed and then used to conduct a parametric study on the response of the foundations of wind turbines exposed to different patterns of loads, and changes in water table and soil moisture content. The detailed simulation of three-dimensional loading of soil subjected to drying/wetting cycles requires the development of an elasto-plastic fully coupled thermo-hydro-mechanical finite element analysis code with an advanced constitutive model.