In recent years, there has been a boom in urban infrastructure projects in and around London that require deep basements to be excavated, such as underground railway stations and shopping malls. The permanent removal of topsoil due to basement construction inevitably causes upward movement of the remaining soil. In London clay and other over-consolidated clay strata, this upward movement continues over many years after the basement structure’s completion, a process known as long-term heave.

Urbanisation causes more and more of such deep basements to be constructed to greater depths and sizes than before. This has renewed interest in research on the long-term behaviour of base slabs in over-consolidated clay, because the basement structure must be designed to accommodate these long-term heave movements. The drive towards green construction techniques in next-generation infrastructure will require the methods of design need to be updated to allow more efficient use of material.

This paper reviews a range of current techniques used in the design of deep basement slabs where significant long-term heave deformations are expected. While current design guidance is sufficient in ensuring the safety of construction and operation of underground urban spaces, there is a strong feeling within the construction industry that the design criteria are inefficient and need to be improved with the help of experimental data.

Geotechnical centrifuge simulation is the main technique for physical modelling of long-term heave behaviour, as artificial gravity allows a year of real-life movements of soil to be replicated in a small-scale model in an hour of laboratory time. This paper reviews recent research in geotechnical centrifuge simulations on heave behaviour of deep excavations in over-consolidated clay, identifying key findings and pointing out areas that will require further research. These experimental simulations will allow the effect of long-term heave to be quantified more accurately in future design guidance, thereby addressing the need to conserve construction material as the requirement for urban underground space increases.