Geotechnical failures: A personal perspective 4th Hanrahan lecture

Geotechnical engineering is both an art and a science as it combines the application of scientific principles with engineering judgement. Such judgement is required because of incomplete and uncertain information but is also critically dependent on the experience of the engineer for any particular application. Experience is greatly enhanced by the lessons learnt from past mistakes. However, all too often, engineering mistakes are not commonly advertised because of reputational damage to the companies involved or to ‘deals’ emerging from litigation. To address this deficiency, this paper describes simple examples of ‘geotechnical failures’ that the author has had direct experience of during his 40-year career as a geotechnical engineer. Standard ‘textbook’ type problems are rarely the cause of failure and the examples selected are those that highlight aspects often under-appreciated in standard practice. Given the broad nature of geotechnical design and construction,focus is placed in this paper on onshore building projects where the author was involved as a post-incident reviewer or expert witness. The lessons learnt are equally applicable to large scale civil projects and offshore engineering.