Soil Mechanics

The soil mechanics research group has, for some time, been involved in investigating the fundamental behaviour of particulate material. This has required the development of novel apparatuses and the ability to measure internal strains away from apparatus constraints. The equipment that has been designed and constructed here is being used in other institutions including the Massachusetts Institute of Technology, Vicksburg Experimental Station USA and the Chr. Michelsen Institute, Norway. Internal strain measurement is made using X-ray techniques and the group has three X-ray sets available.

Recently work has concentrated on testing soils at very low stress levels in model situations and in element testing apparatuses with the necessary equipment developed to overcome boundary constraints. This work has special relevance to sea bed soils.

Work into the effects of cyclic loading on soil behaviour has been in progress for several years and is continuing. This also has applications in the chemical engineering industry and research grants have recently been awarded to investigate the behaviour of powders of various water contents under cyclic loading using a Directional Shear Cell that has the ability to apply principal stresses in any direction. The influence of long-term cyclic loading of granular soil/structure interaction is being investigated to determine design criteria for retaining walls and the foundations of structures. In collaboration with the dynamics and earthquake group, experimental work is being carried out on the dynamic loading of masonry and its incorporation in buildings for torsional shear walls.

In addition, the group has expanded its particular interest in the measurement of displacements and strains to both physical laboratory model tests and to displacements in the field. The data is used to examine the mechanisms associated with a number of soil/structure interaction problems. Particular emphasis has been given to the behaviour of tunnels, the effectiveness of reinforced earth walls and reinforced embankments and the detailed deformation caused by penetration. The results are compared with numerical methods.

The Soil Mechanics research group has also recently extended its area of interest to the constitutive modelling of natural soils. Natural soils have a different microstructure or structure to soils that are reconstituted in the laboratory. Natural structure is formed during and after sedimentation by geological processes such as creep, thixotropy, cementation, or more generally diagenesis. One of the effects of natural structure is to convey extra strength to natural soils, allowing them to exist at a higher void ratio than the equivalent reconstituted soils at a given stress. However in some soils the structure is not stable and breaks down with plastic straining; this is called destructuration. Natural structure and destructuration have been included in an advanced constitutive model for natural clays. Future work involves ascertaining the expression controlling destructuration, which will achieved by conducting a series of specifically designed tests. Ageing, and in particular formation of structure, will also be investigated with the aim to develop existing advanced constitutive models further.

The academic staff of the group are:

Emeritus Reader in Geomechanics
Richard Bassett  

Lecturer in Soil Mechanics, Head of Soil Mechanics Group
Beatrice Baudet  Ingenieur ETP, MSc, PhD

Lecturer in Soil Mechanics
Yi Pik (Helen) Cheng  PhD, MPhil, BEng

Visiting Professor
Michael Cooper  

Lecturer
Pedro Ferreira  DSc, MSc, Civil Engineering Degree

Lecturer
Raul Fuentes  EUR ING, MSc, Ingeniero, Civiling. MIDA, CEng MICE

Lecturer in GNSS, Navigation and Location Technology
Paul D Groves  MA (Oxon), DPhil, CPhys, FRIN

Honorary Senior Research Fellow (Industrial Metrology)
Stephen Kyle  

Researcher
Yasuko Sadahiro  BSc,MSc