Geotechnical Engineering 2

Description

Overview: The class covers the design of geotechnical structures from foundations (shallow and piled foundations) to slopes and retaining walls, based on British Standards and Eurocode 7. Syllabus: Topic 1. Preparatory concepts Stresses and strains in two-dimensional problems. Mohr's circle for plane stress. Perfect plasticity. Shears strength under drained and undrained conditions (in saturated soils). Effective stress and total stress analysis. The concept of cohesion (effective `true? cohesion, effective `peak strength? cohesion, undrained cohesion). Laboratory and field measurement of shear strength. Limit analysis (upper and lower bound theorems of plastic collapse). Topic 2. Introduction to geotechnical design Foundation design based on permissible stress method and limit state analysis, serviceability limit state and ultimate limit state in geotechnics, design according to EC7, process of geotechnical design, observational method, overview of possible foundation methods, including ground improvement Topic 3. Stability analysis of geostructures Limit analysis (upper and lower bound theorems of plastic collapse).Application of lower and upper bound theorems to the analysis of collapse of excavations, retaining structures, slopes, and shallow foundations. Topic 4. Slope stability Different types of slopes and slope failures (rotational, translational and compound slips), factor of safety in slope stability (BS vs. Eurocode 7), short term and long terms stability, change in factor of safety in time for cut slopes and embankments, limit equilibrium method and its limitation, undrained analysis using circular slips, Taylor's stability charts, surcharges and line loads, tension cracks, submerged slopes, method of slices for undrained and drained analysis (Fellenius, Bishop), translational slips, compound slips (Janbu), stability of embankment dams (end of construction, in service, rapid drawdown) and flood protection embankments. Topic 5. Earth retaining structures Earth pressures revisited (at rest, active and passive), Rankine and Coulomb theories & earth pressures according to BS8002 and EC7, mobilisation of earth pressures as a function of displacements, effect of wall flexibility to earth pressures, influence of back filling/compaction, design of retaining walls (characteristic and design values), ultimate limit states (sliding, overturning, global failure, bearing capacity failure & structural failure), gravity walls and RC concrete walls (principles and design), embedded retaining walls (Berlin method, sheet piles, contiguous piles, secant piles, diaphragm walls- methods, suitability and limitations, models of failure and development of earth pressures, fixed earth support method and free earth support method), braced excavations, serviceability limit state, critical assessment of methods of analysis, small strains vs. large strains and retaining wall design, ground anchors. Topic 6. Shallow foundations Bearing capacity of shallow foundations: Ultimate bearing capacity, general shear failure, local shear failure and punching shear failure, general shear failure of infinite strip footing, bearing capacity factors (Brinch Hansen), undrained bearing capacity, ultimate, allowable and safe bearing capacity. Settlement of shallow foundations: Stress distribution and settlement, contact pressure (distributed loads and point loads), stress distributions due to foundation loading for different foundation shapes (assumption and limitations, principle of superposition, immediate, consolidation and creep settlements. Topic 7. Pile Foundations Types of deep foundations, ultimate load capacity of pile foundations, single piles and pile groups, design of pile foundations and pile groups. Learning Outcomes: o Understand and apply the principles of geotechnical design based on British Standards and the philosophy of Eurocode 7, considering limit states (ultimate & serviceability). o Understand and apply the methods to analyse the collapse of geotechnical structures o Understand the principles governing the stability of slopes in various soil types including natural slopes, cuttings, embankments and earth dams. o Calculate the stress states in soil slopes and their changes with time and loading conditions. o Understand the applicability of the various soil slope stabilisation measures. o Understand earth pressures and analyse the stability requirements of the different types of wall structures, taking particular account of wall flexibility and reinforcement type where appropriate. o Calculate the ultimate, safe and allowable bearing capacities of shallow foundations, taking account of load inclination, load eccentricity and ground water levels. o Calculation the ultimate safe and allowable loads in single piles and pile groups. Design of single piles and pile groups in different ground conditions. o Competence in the use of computer software for the design of slopes, retaining walls and foundations (GEOSLOPE, REWARD). Assessment: Assessment Method(s) Including Percentage Breakdown and Duration of Exams: Examination: -Duration = 3 hours -Weighting = 70 Coursework: -No. of Assignments = 1 -Weighting = 30 Coursework / Submission deadlines: G41 Geotechnical Design Project ; Sem 2, Week 4 ; Weighting = 30%