This course covers problematic soils (soft and sensitive clays, expansive soils and collapsible soils) and numerical modelling of geotechnical problems.

2 lectures per week

None

None

60% Written Exam

40% Written Assignments

The aims of this course are to:

■ provide an appreciation of the engineering behaviour of various categories of problematic soils (soft, sensitive and quick clays; expansive soils, collapsible soils and the role of unsaturated conditions) and how this can impact upon geotechnical design;

■ develop knowledge and competency in the use of finite element software (Plaxis 2D) for modelling geotechnical problems such as foundations and excavations.

By the end of the course students will be able to:

■ describe clay-water-chemical interactions and apply diffuse double layer theory to explain the mechanism for high sensitivity in clays;

■ describe the significance of creep and rate-dependent behaviour in soft clays and use a simple one-dimensional elasto-viscoplastic model to predict the development of creep settlement of a loaded foundation over time;

■ explain the effects of suction and capillarity in unsaturated soils, the occurrence of swelling or collapse compression on wetting and the use of net stress and matric suction as stress state variables for unsaturated soils; use this knowledge in the solution of simple engineering problems involving unsaturated soils;

■ use a linear elastic-perfectly plastic constitutive model with a Mohr-Coulomb failure criterion to predict soil behaviour in triaxial tests under drained and undrained loading; show an appreciation of the strengths and limitations of this simple constitutive model for soils;

■ use Plaxis 2D finite element software to undertake numerical modelling of a range of geotechnical problems (shallow foundation, excavation, etc), demonstrating an appreciation of: selection of constitutive model; choice of coupled hydro-mechanical (consolidation), uncoupled mechanical (i.e. drained or undrained) or uncoupled hydraulic (i.e. seepage) analyses; selection of boundary conditions; setting up the mesh; and influence of increment size.

Students must attend the degree examination and submit at least 75% by weight of the other components of the course's summative assessment.

Students must attend the timetabled laboratory classes.

Students should attend at least 75% of the timetabled classes of the course.

Note that these are minimum requirements: good students will achieve far higher participation/submission rates. Any student who misses an assessment or a significant number of classes because of illness or other good cause should report this by completing a MyCampus absence report.