Geotechnical Engineering

All engineering structures are founded on or within the earth, and such foundations must be structurally sound, stable (safe), serviceable and cost effective. The ground must be strong enough to resist the applied load through the foundation and must not exceed reasonable settlement limits. It is important therefore that civil engineering students develop the key skills necessary to analyse and design different types of foundations and other earth-related structures in a range of different soil and rock types so as to satisfy these criteria. Such foundations and structures include both shallow and deep footings, slabs, embankments, and retaining walls of various types. Students should also understand a number of key construction issues such as dewatering, excavation stabilization, and soil improvement, and be able to design systems for same. On-going visits made over several weeks to sites where significant foundation construction work is being undertaken form a key part of this unit and are aimed at helping students acquire skills and understanding as indicated above.

Key topics include: Introduction to foundation design. Bearing capacity of shallow pad and strip foundations on fine and coarse-grained soils. In-ground stress distribution due to applied loads. Foundations on reactive soils. Bearing capacity of single driven and bored piles, and of pile groups. Immediate settlement. Consolidation theory and consolidation settlement of foundations on fine-grained soils. Settlement rates and allowable settlement. Lateral stresses in the ground. Active and passive stress states. Analysis and design of gravity and cantilever retaining walls. Introduction to construction issues including ground stabilisation and dewatering. Types and uses of geosynthetic materials.