Challenging the Unchallengeable: Revisiting the Soil Mechanics Paradigm

Project ID: 2228cd1272 (You will need this ID for your application)

UCL Lead department: Civil, Environmental and Geomatic Engineering (CEGE)

Project Summary:

The discipline of Soil Mechanics is utterly dependent on the Principle of Effective Stress, and this is therefore the basis of every design for every geotechnical structure worldwide, dams, tunnels, foundations, etc. It is a “principle” and not a law precisely because it cannot be proven. It is therefore essentially empirical and it states that all soil behaviour is dependent on the difference between the applied stresses and the pressure of the interstitial water between the soil particles.

The nature of the actual forces acting between particles has been illuminated in recent years, notably by unique and world leading apparatus developed by us at UCL that investigates the force transmission between two soil particles. A key limitation though, is that it can only examine particle contacts in the presence of water and not under pressurised water. In common with our entire discipline, it assumes that the effect of water pressures at the contact can be excluded by when Effective Stress is considered.

We seek an imaginative experimental engineer to join our Geotechnical Research Group at UCL in this quest, under the supervision of Professor Matthew Coop and Dr Pedro Ferreira. The PhD student will make innovative changes to our apparatus to apply water pressures at the particle contacts while we explore the contact mechanics. This will allow deconstruction of our governing principle examining the very basis of our entire discipline. This will be technically challenging. The probability is that we will give the principle a firmer basis, a remarkable step in itself, but the tantalising possibility is that we may identify limitations to its applicability.