Unwin Memorial Lecture 1992 Developments in geotechnical engineering research: Application to tunnels and deep excavations

• Published in: Proceedings of the Institution of Civil Engineers. Civil engineering 1993-02, Vol.97 (1), p.27-41
• Main Author: Mair, R J
• Format: Article
• Language: English
• ISSN: 0965-089X
• DOI: 10.1680/icien.1993.22378

Advances in techniques of site investigation, laboratory testing, modelling, analysis and field measurements have resulted in improved understanding of ground behaviour in underground construction. Some of these advances are highlighted, and their application to design and construction is illustrated by case histories of bored tunnel construction and deep excavations. A key aspect of soil behaviour influencing ground response around tunnels and excavations is the variation of stiffness with strain level. Examples are given of the laboratory and in situ measurement of stiffness properties at low strain levels and the use of such measurements in the prediction of ground behaviour. The use of electrolevels for observations of deformations of ground and retaining structures is illustrated. Measurements are described which demonstrate that ground movements are significantly less for hand-excavated large diameter bored tunnels in stiff clay when a pilot tunnel is constructed.