The Engineering Properties of Glacial Tills in the Taff Valley, South Wales

  • J.D. Lewis

    Student thesis: Doctoral Thesis


    The present study assesses and examines the range of geotechnical properties that are to be experienced during an investigation of the glacial and periglacial soils of the Taff Valley.

    The study procedures adopted and the techniques used were chosen from a review of the relatively limited literature relevant to the subject.

    Detailed engineering geological and geomorphological mapping was carried out at a scale of 1:10000. Geological mapping has shown that the nature of lodgement tills is much more strongly dependant on local bedrock geology than that of
    melt-out tills and fluvioglacial deposits. Solifluction deposits closely resemble the soil types from which they are locally derived.

    Geomorphological mapping has provided a suitable method of identifying and genetically classifying soils when related to models of glacial and periglacial processes. These models should be used to assist in the design of ground investigation
    programmes to ensure their efficiency in terms of data retrieval and cost.

    Quantitative studies of soil mesofabric have been used effectively to interpret local and regional glacial regimes and also to delineate areas of past and present slope instability. Qualitative studies using the scanning electron microscope have demonstrated that glacigenic soil types may be genetically differentiated and classified upon the basis of microfabric characteristics.

    Laboratory testing (classification, shear strength and permeability) has identified significant geotechnical differences between soils of differing modes of genesis and post-depositional history. The range of engineering properties attainable is directly attributable to textural heterogeneity within and between soils, particularly in terms of relative degrees of clast and matrix dominance.

    An investigation of the permeability characteristics of these soils has enabled reliable estimates to be made of the permeability of gap and well graded glacial soils by relatively cheap indirect methods. Grading curves and the modified Kozeny-Carman equation with a suitably applied correction factor have been used.

    The theories of soil genesis that are presented and the relationships that are drawn between soil types, landforms and geotechnical properties could provide a basis for the interpretation of site investigation data in other localities and regions that have undergone or are currently undergoing glaciation.
    Date of AwardJul 1983
    Original languageEnglish
    Awarding Institution
    • Polytechnic of Wales

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