Department of Architecture & Civil Engineering, Unit Catalogue 2009/10 |
AR20076: Soil mechanics |
 Credits:
| 6 |
| Level:
| Intermediate |
| Period: | Semester 1 |
| Assessment:
| CW 20%, EX 80% |
| Supplementary Assessment: | AR20076 Reassessment Exam (where allowed by programme regulations) |
| Requisites:
| |
| Description: | Aims: To develop an understanding of the behaviour of soil, and the factors that influence that behaviour. Learning Outcomes: The successful student should be able to demonstrate understanding, and an ability to apply that understanding, in the following subjects, as detailed in the 'Contents' section: * Stresses in soil; * Seepage and flow nets; * Measurement of permeability; * The shear strength of granular and cohesive soils; * Measurement of fundamental shear strength, and of the current state of a sample. Skills: Basic soil mechanics laboratory technique, graphical and algebraic analytical methods. Content: Stresses in soil - total stress, effective stress and pore water pressure. Non-linear stress-strain character of soils. Isotropic and one-dimensional consolidation. Consolidation of natural deposits, normally consolidated and over-consolidated materials. Seepage, Darcy's law of permeability, head as a measure of potential. Wide range of permeability values. Flow nets, derivation from a common sense approach, how mathematical 'derivation' is merely a formularisation of this. Determination of volumetric flow rates by Nf/Nh. Relative importance of predictions of volumetric flow rates and pore pressures. Sensitivity to inaccuracy of flow net. Prediction and importance of low effective stresses. Measurement of permeability, use of triaxial apparatus as a permeameter. Falling head and constant head tests. Pumping tests - confined and unconfined aquifers. Flow nets for anisotropic permeability. Outline of other approaches to analysis of flow - physical / electrical / computer numerical modelling. Seepage in earth dams, importance of drainage, stability of downstream face, rapid drawdown. Influence of rainfall. Design of filter layers, use of geotextiles. The shear strength of granular and cohesive soils. Mohr's circles of total and effective stress to determine the undrained and drained shear strength and friction angle of soils. Stress/strain relationships for soils, behaviour of normally consolidated clays. Behaviour of loose and dense samples, concept of a critical state, introduction to behaviour of lightly and heavily overconsolidated clays, dependence of critical state density on normal stress. Relationship between normal consolidation line, Roscoe surface, Critical State Line, Hvorslev Surface, zero tension criterion. Shear strength tests, the advantages and disadvantages of the direct shear test, the triaxial test, vane shear test, other tests. Total and effective stress paths for drained and undrained testing. Obtaining information about current state of a sample (undrained shear strength) compared with fundamental properties (drained shear strength / critical state parameters) from triaxial testing. |