Ian Jefferson

Some major events in the development of the scientific study of loess

Abstract A European view of loess history is presented. The major events, or ‘great moments’, considered are (1) Karl Caesar von Leonhard names loess; (2) Charles Lyell popularises loess; (3) Richthofen solves ‘The Loess Problem’; (4) John Hardcastle relates loess to climate; (5) Pavel Tutkovskii makes clear the role of glaciers in loess genesis; (6) V.A. Obruchev makes the case for desert loess; (7) L.S. Berg propounds the ‘in-situ’ theory of loess formation; (8) Rudolf Grahmann maps loess in ‘Europa’; (9) R.J. Russell adopts the ‘in-situ’ idea; (10) Liu Tungsheng pioneers Chinese loess stratigraphy; (11) Julius Fink focuses loess research in the INQUA Loess Commission; and (12) George Kukla reshapes the Quaternary by way of loess research. The need for Chinese, Russian, and North American accounts to balance an authoritative view of loess history is recognized. The truly critical moment in the 20th century was the discovery by Liu Tungsheng and his colleagues of multiple palaeosols within the Chinese loess and the associated realization that these implied a multi-event Quaternary.

Liquid limit and the temperature sensitivity of clays

Abstract The Atterberg Limits have been repeatedly shown to be useful indicators of clay behaviour. This paper proposes that they should also be used to assess the effect of temperature on clays. To improve on previous attempts, this paper describes a new simple and rapid method by which such assessments can be made. The method enables consistent results to be obtained over a larger range of temperatures (i.e. 10–80°C) than previously possible. This method is, therefore, potentially useful when assessing the behaviour of clay soils which are likely to be exposed to elevated temperature, such as landfill liners. Results are presented for kaolinite, smectite and mixtures of these clays of various percentages. These demonstrate that smectites are considerably more sensitive to temperature changes than kaolinites. For smectitic clay the liquid limit increases with temperature, whereas a very slight decrease occurs with kaolinite. The variation in liquid limit appears to be closely related to the specific surface area of the clay, and the resulting nature of inter-particle contacts.

Engineering geology of loess and loess-like deposits: a commentary on the Russian literature

Loess and loess-like deposits were much studied in the Soviet Union, and are currently under investigation in Russia and surrounding countries. There is a vast literature in Russian, which touches on all aspects of loess science and technology. In particular, the studies of the origin of collapsibility are almost totally in Russian, and of course studies on the various regions of Russia and the countries of the Former Soviet Union FSU appear in Russian. This review looks at the literature in Russian and attempts to pick out key contributors, major topics and works and to identify the critical regions and zones of investigation. Because so many regions of the FSU had people living on loess ground, there is a vast literature on engineering geology and ground engineering topics, and this tends to dominate all the literature on loess in Russian. Following Russian practice, the fine-grained deposits under consideration are divided into loess and loess-like deposits. Three main topics are recognised across the whole spectrum of loess research: formation and distribution of loess deposits; stratigraphy, cyclicity and palaeoclimatology; and engineering topics, in particular hydrocollapse and subsidence, and we concentrate on the engineering geology topics. An attempt is made, based on the map of Abelev and Abelev [Abelev, Yu.M., Abelev, M.Yu., 1968. Fundamentals of design and construction on collapsible macroporous soils, 2nd ed. Stroiizdat, Moscow, 431 pp. (in Russian)] of collapsing loess deposits, to define seven loess regions within the geographical limits of the old USSR. The seven regions are those where geotechnical problems might be expected.

Fractal characteristics of loess formation: evidence from laboratory experiments

The fractal is presented as a method for describing the geometry of particles, with particular reference to the breakdown of granular soils and the formation of loess. The preliminary results are reported: (a) for the extent to which silt due to comminution exhibits a fractal distribution; (b) the tendency of fractal dimension to change with the comminution process; and (c) the relationship between fractal dimension describing particle size distribution and the grinding time. Laboratory simulation confirms the general tendency of fractal characteristics to reflect the size reduction process.

The Treatment of Collapsible Loess Soils Using Cement Materials

Loess is a metastable collapsible soil, whose collapse can cause significant distress to the built environment across the world. This paper presents a case history illustrating how with proper pre-treatment assessment and careful selection, a cement based treatment approach was used successfully to improve a collapsible loess soil. This case history illustrates that even for structures when very tight specifications for post treatment performance exist, it is still possible to build safely on a problematical loess soil.