Abstract
The plastic limit of soils was first described by Atterberg in 1911. The thread-rolling test was standardised at the US Public Roads Bureau in the 1920s and 1930s, and has subsequently become one of the standard tests of soil mechanics. This paper reviews the original definitions of plastic limit as proposed by Atterberg, and proposes that the brittle failure observed in the plastic limit test is caused by either air entry or cavitation in the clay. Critical state soil mechanics is used to show that the observed range of undrained shear strengths of soils at plastic limit is consistent with this hypothesis. The fallacy that strength at plastic limit is a constant is highlighted, and the implications for geotechnical practice are discussed.
Highlights
This edition of Géotechnique presents the latest in the series of ‘symposia in print’ published in the journal and addresses the theme of linear infrastructure and slopes
The topic of ‘linear infrastructure and slopes’ was chosen because in recent years, and as a consequence of the Covid-19 pandemic, there has been a significant increase in the number of linear infrastructure projects being planned and under construction in the UK and internationally
It recognised that there are significant resources involved in the ongoing maintenance of linear infrastructure and ensuring ageing assets remain serviceable and safe
Summary
This edition of Géotechnique presents the latest in the series of ‘symposia in print’ published in the journal and addresses the theme of linear infrastructure and slopes. The topic of ‘linear infrastructure and slopes’ was chosen because in recent years, and as a consequence of the Covid-19 pandemic, there has been a significant increase in the number of linear infrastructure projects being planned and under construction in the UK and internationally. It recognised that there are significant resources involved in the ongoing maintenance of linear infrastructure and ensuring ageing assets remain serviceable and safe.
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