Winner announced of 2018 BGA MSc/MEng Prize

The British Geotechnical Society (BGA) is pleased to announce that Isabel von Celsing of the University of Oxford is the winner of the 2018 MSc/MEng prize for her dissertation entitled “Offshore Wind Turbine Foundation Design Using 3D Finite Element Limit Analysis”.

The dissertation by Melissa Mia Tait of Imperial College London on “The effects of small strain stiffness and stiffness degradation on slope failure” was highly commended.

The MSc/MEng Prize is awarded annually by the BGA for the best Masters’ degree dissertation on a geotechnical topic. The five dissertations submitted for consideration were:

• Isabel von Celsing, University of Oxford, "Offshore Wind Turbine Foundation Design Using 3D Finite Element Limit Analysis".
• Chung Yiu Barry Chau, UCL, “Numerical analysis of the construction sequence of the new development in Battersea power station”.
• Aliz Horváth, University of Dundee, “Examining inclined installation of screw anchors scaled up for offshore renewable energy deployment”.
• Melissa Mia Tait, Imperial College London, “The effects of small strain stiffness and stiffness degradation on slope failure”.
• Thomas Woolley, Leeds University, “Scale-dependency of soil/geosynthetic interface shear strength, and its implications in landfill engineering”.

Isabel von Celsing’s MEng dissertation describes a sensitivity study of monopole performance in clays, using Professor Martin’s Finite Element Limit Analysis program OxLim. It was found that in addition to the soil lateral resistance, components from base moment, base shear and distributed moment along the pile all contributed significantly, because the failure mechanism was not simply the conical wedge often assumed but included a spherical bulb around the base. These other contributions varied significantly with the input soil parameters and pile geometry.

Chung Yiu Barry Chau’s MSc dissertation was carried out in a collaborative project with BuroHappold Engineering, analysing displacements at Battersea power station by means of finite elements. It was demonstrated how using a cap model accounting for small strain stiffness gave superior predictions to a simple elastic model with a Mohr-Coulomb failure envelope. The input parameters for London clay in the small strain model were optimised.

Aliz Horváth’s MSc dissertation described an experimental and finite element investigation of the use of inclined screw anchors for use with offshore floating structures in deep water, showing how inclining the screw anchor could improve the foundation capacity and its stiffness.

Melissa Mia Tait’s MSc dissertation addressed the delayed collapse of cuttings in stiff clays by means of finite element analyses. It was demonstrated that the soil behaviour in the small strain region had a significant impact on long-term stability and that both the bulk and shear moduli were important.

Thomas Woolley’s MSc dissertation discussed a laboratory investigation of the effects of shear box size when assessing the interface shearing behaviour of geosynthetics with soils for applications in landfill engineering. Although there were scale effects, the shear strengths measured were generally not dependent on the size of the shear box for either sands or clays and so a standard 100mm shear box could be used in design, saving the cost of tests in larger devices. The texture of the geosynthetic was found to have a strong influence.

The judges found all the Master’s degree dissertations to be of a high standard and the final decision was close. Isabel von Celsing’s MEng dissertation was selected as the winner of the 2018 MSc/MEng prize, with Melissa Mia Tait’s being highly commended.