VIENNA TERZAGHI LECTURE

The „Vienna - Terzaghi Lecture “ is the traditional highlight of the Austrian Geotechnical Conference.
In the case of 14. AGC 2024 the lecture will be held by

Prof. Giulia VIGGIANI
University of Cambridge
Professor of Infrastructure Geotechnics in the Department of Engineering, Director of Studies in Engineering, Buildings Advisor

On the behaviour of pile groups under generalised loads

The lecture will focuses on the bearing capacity of pile groups subjected to combined vertical, moment
and lateral loads. Advanced three-dimensional (3D) finite-element analyses were used to identify the
possible plastic mechanisms occurring within the soil–foundation system, as well as the most relevant
factors affecting its limit behaviour. The numerical results show a strong coupling between the lateral
capacity of the group and the applied vertical/moment loads, resulting from a different degree of
mobilisation of the axial and bending capacity of the piles. Based on the numerical findings, a new
theoretical lower bound solution was developed to compute the 3D failure domain of pile groups in clay,
overcoming limitations and inconsistencies of existing theoretical solutions. The proposed solution
accounts for the combined effect of group geometry, structural and geotechnical capacity of the single
piles, and loading direction, on the actual plastic mechanism occurring within the group and the
corresponding failure envelope. The method was validated by comparison with the results of centrifuge
test on small scale models of pile groups and full scale field tests.