Research Theme – Should we still be logging boreholes using the Human Eye?

A question posed by the Andy Gibson ( Director of the Centre for Applied Geoscience Research, University of Porstmouth) at their first industry workshop exploring their current research looking at the ” Rapid Characterisation of the London Clay Formation using VNIR (reflectance Spectroscopy).  By the end of the session you could certainly see that there is whole lot more structure, lithological and mineralogy variations in London Clay that the human eye, even a well-trained one, misses.  Given that the geotechnical behaviour of the London Clay can be related to lithology and clay mineralogy and that some of these changes can occur in thin layers often less than 10mm thick, being able to readily log seemingly unvarying cores of London Clay, could be of real value to the industry.

The research to date is seeking to:

  • develop a high resolution (10mm) lithostratigraphy  of the London Clay Formation intially utilising the almost complete succession of London Clay  at Whitecliff Bay on the IOW
  • evaluate the ability of VNIR  Spectroscopy to identify weak layers
  • develop a technique to identify where the London Clay formation is weathered and unweathered and as a result VNIR Spectyroscopy measurements are being used to look at:
    • Lithofacies
      • Partcicle Size Distribution
    • Geotechnical Properties
      • Moisture content
      • Atterberg Limits
    • Mineralogy
      • Clay ( species amd crstallinity)
      • Non-clay
        • Pyrite
        • Gypsum
        • Fe2/Fe3
  • Characteris diagnostic features key lithological and weathering boundaries (supported by XRD and SEM)
  • Determine whther VNIR could be used as an improved technique to routinely identify the type and nature of weathering in London Clay during geotechnical investigations.

However those attending the workshop could see wider uses for it including:

  • rapid mositure content assessment tool in large scale earthworks;
  • delineating the depth of desssication of shrinkable clays in the field;and
  • delineating between contaminated and uncontaminated soils.

If you would like to know more, be involved, provide support eg access cores or even fund further research then GEMs would be pleased to hear from you.