Hydraulic Heave Failure in EC7: Suggestions for Verification

Hydraulic failure by heave is one of the most dangerous limit states in geotechnical engineering practice. Hence, the margins of safety associated to this failure mechanism have traditionally been quite high. Nowadays, with the advent of the Eurocodes, the approaches to verify heave failure have been substantially modified to take into account “partial” factors, as opposed to the traditional “global” safety factor. In the paper it is demonstrated that the two approaches given in the present version of Eurocode 7 do not provide a consistent evaluation of safety against failure by heave and may lead to both over-conservative and un-conservative design. An alternative approach is given to eliminate such inconsistencies, and to provide more reasonable levels of safety. Finally, two simple examples are presented to compare the different approaches and to highlight possible limitations in their use for design.