Summary
Metastable partially saturated soils are those which on wetting under load undergo a sudden decrease of void ratio, i.e. a structural collapse. One of the most important soils of this group is loess, a silty quartzose sediment of uniform grading. Loess has attracted interest in the past because of its unusual mode of formation associated with wind transport, and its unusual behaviour as an engineering material. It has extremely widespread occurrence outside Britain but only occurs to any extent in small areas in east Kent and has only been reported occasionally from elsewhere in Britain.
The paper deals principally with the geotechnical and mineralogical characteristics of east Kent loess and some comparison is drawn with loess from various world-wide locations. The geotechnical behaviour supports the conclusions made from earlier geological observation which leave little room for doubt that the Kent loess is a true loess of periglacial origin. A coarser grained poorly sorted glacial solifluxion soil from Kent was also examined and found to be metastable. Because material of this type is fairly common this observation could have significant engineering implications.
Summary
Some geotechnical properties of the ballclays of Devon have been related to their mineralogical composition, sedimentary depositional environment and tectonic setting. Small scale sedimentological structures of these predominantly disordered' kaolinitic clays indicate shallow water deposition in a fluvio-lacustrine environment which existed during Oligocene times in the Lustleigh-Sticklepath fault zone. The two principal types of ballclay, the stoneware and whiteware ceramic varieties, have consistently different negative liquidity indices which imply different degrees of overconsolidation. The differences of consistency between the stoneware and whiteware ballclays are considered to have arisen as a result of variations in the intensity of desiccation to which the individual beds of ballclay were subjected shortly after deposition, when receding flood waters allowed drying of the fresh sediment.
The stoneware ballclays are typically stiff to hard, apparently 'intact' clays found inter-bedded with silts and sands, whilst the whiteware clays are hard or very hard, highly fissured and slickensided slightly lignitic clays which occur in close association with lignite seams and in many respects resemble underclays from coal-bearing sequences. Overconsolidation is considered to result principally from desiccation of the individual beds of clay, hence estimates of the former maximum thickness of the ballclay deposits within the Lustleigh-Sticklepath fault zone from one-dimensional consolidation tests using undisturbed and remoulded specimens are precluded.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.