Engineering & Geotechnical Capability

BGS Science Facilities

BGS are world leaders in visualising the subsurface, which combined with parameterised ground models, provides a platform for characterising and quantifying the ground’s behaviour. We apply this understanding to our interactions with the subsurface to support sustainable energy, environmental and ground engineering activities. Realising the natural capital provided by the ground in these areas requires continued sampling and measurement of the subsurface and the Engineering and Geotechnical Capability (EGC) was established with this in mind.

EGC provides the infrastructure underpinning field and laboratory R&D, and the long-term management of geophysical and geotechnical property data at BGS. Figure 1 shows the structure of the EGC:

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Figure 1. Engineering and Geotechnical Capability: Internal structure and linkages. Source: BGS © UKRI

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Figure 1 also shows the data pathways through the EGC. As well as the data generated by our research programme, we also ingest 3rd party data from UK site investigations. The laboratory and field data generated by our research supports the BGS strategic programme for multi-scaler ground model visualisation and attribution.

We specialise in the analysis, interpretation and problem solving integral to research and development. From simple measurements and beyond, we offer bespoke solutions to BGS core science and commissioned research programmes, providing single facility to integrated service support. Our services include:

  • innovative R&D solutions for field and laboratory activities and apparatus;
  • in situ field measurement, sampling and laboratory testing of geological materials; collation and digitisation of UK site investigation data;
  • maintenance of the National Geotechnical Properties Database; data analysis to support the parameterisation of the National Geological Model;
  • development of geotechnical – geophysical property relationships to support and quantify geophysical monitoring activities;
  • geophysical monitoring activities for ground visualisation, natural and engineered asset condition and performance indices;
  • ground characterisation of natural and engineered ground including landslide observatories, geotechnical earthworks and seismic amplification.

Engineering and Geotechnical Capability ground characterisationFigure 2: High resolution ground characterisation for engineering applications. BGS © UKRI

 

We don’t simply make measurements of the ground, we integrate these measurements into coherent ground models at a scale that is fit for purpose for a range ground engineering applications. Figure 2 above shows the application of high-resolution, resistivity and non-invasive shear wave velocity mapping methods to image an infilled meander channel in alluvium on the River Trent Floodplain. The 2D section highlighted runs parallel to the current West Coast Rail Mainline and was formerly chosen as the route for the HS2 rail line. Fine soft soils infilling the meander pose potential challenges to construction due to consolidation affecting the bearing capacity and may also amplify train-induced ground vibrations. (N.B. the HS2 route has since been re-designated further to the NW.)

Understanding ground behaviour is core to understanding the performance of critical UK infrastructure, and indeed, how it changes with time. Key hydrogeological, geophysical and geotechnical properties control ground behaviour in excavations, foundations, tunnels and engineered fill.

For over 20 years, our research has generated a wealth of data and information on the engineering performance of the geological formations strategically important to UK infrastructure and development.  This research undertaking has led to the characterisation of major bedrock and superficial formations in terms of their engineering, which can be accessed via our information products including:

Navigate to our publications and case studies section to download case studies relating to:

  • historical development of geophysics in the UK
  • impact assessment of strength of ground supporting a leaking water pipe
  • system for inspecting underwater piled foundations
  • novel apparatus for soil shrinkage testing
  • anatomical imaging of aged railway embankments

Publications and case studies

This study demonstrates the use of Multi-channel Analysis of Surface Waves (MASW) to measure changes in Rayleigh wave velocity relating to both the initial trench construction and subsequent simulated failures (water leaks) of a buried water-pipe. The MASW field trials were undertaken in conjunction with a wider suite of geophysical monitoring techniques at a site in South-west England, within an area of clayey sandy silt. The Rayleigh wave velocity through a soil approximately equals the shear wave velocity, which in turn is predominantly dependant on the shear modulus of the soil (G) and this can be inferred to give a measure of the relative strength of a soil. It is proposed that the time-lapse measurement of Rayleigh wave velocity may be used to monitor ongoing changes in soil strength and therefore the MASW technique could perform a significant role in monitoring the initiation/progression of any internal processes within a geotechnical asset, before they would otherwise be identified through visual inspection alone.

Download the complete case study:

Dashwood, B.A.J., Gunn, D.A., Curioni, G., Inauen, C., Hobbs, P.R.N. & Reeves, H. (2019). Surface wave surveys for imaging ground property changes due to a leaking water pipe. Jour. Applied Geophys.

At present, British (BS 1377, BSI, 1990) and American (D427-04; T92-97) standards describe soil shrinkage measurements via displacements of liquid mercury in which the sample is immersed. Both methods present a significant health hazard related to the spread of the mercury vapours, leading to a ban on its use in many soils laboratories. The BGS system, called SHRINKiT employs laser-scanning, combining successive hi-resolution volume and mass measurements to determine soil shrinkage limit.

Download the complete case study:

Surface wave surveying is a field geophysical technique used to assess the small strain stiffness characteristics of railway subgrade and geotechnical assets. These surveys captured complex structures consistent with end tipping within an aged Victorian embankment. Anatomical imaging of the asset was possible, enabling the location of stiffness contrasts between different fill materials needed to understand dynamic load performance and early identification of progressive subgrade deterioration that precedes track geometry problems.

Download the complete case study:

This paper discusses the development and application of geophysical techniques from a historical UK perspective. Covering the last 50 years, this study begins in the 1960s with geophysical exploration in former African dependencies. We also show how the development of seismic surveying for hydrocarbons through the 70s and 80s is linked to our post-war motorway expansion, and how the regeneration of our urban centres through the 90s and 00s provided the catalyst for geophysical methods to help characterise disturbed and contaminated ground. We take a final look at the issue of swelling urban populations and the need for very high-resolution methods to aid detection and laying of utility infrastructure within a congested cityscape.

Download the complete case study:

Gunn, D.A. (2017). The Geophysics Contributions from the Quarterly Journal of Engineering Geology & Hydrogeology, 1967 – 2015. QJEGH, Vol. 50, 379-392.

 

Fossil fuel and renewable energy supplies rely upon offshore platforms constructed in the shallow seas about the UK. Injected concrete grout joins the steel sub-structures used in the foundations supporting these platforms on the seabed. The foundation sub-structure joint comprises concrete-grout sandwiched between two steel plates. The condition of the grout deteriorates with time and can develop cracks at its interfaces with either steel sub-structure. This case study describes the development of an underwater inspection system that uses ultrasound beamed onto the outer faces of the steel plates to inspect the condition of the internal grout joint.

Download the complete case study:

Haslam, E.P.; Gunn, D.A.; Jackson, P.D.; Lovell, M.A.; Aydin, A.; Prance, R.J.; Watson, P.. 2014 Novel laboratory methods for determining the fine scale electrical resistivity structure of core. Journal of Applied Geophysics, 111. 384-392.

Chambers, J.E.; Gunn, D.A.; Wilkinson, P.B.; Meldrum, P.I.; Haslam, E.; Holyoake, S.; Kirkham, M.; Kuras, O.; Merritt, A.; Wragg, J.. 2014 4D electrical resistivity tomography monitoring of soil moisture dynamics in an operational railway embankment. Near Surface Geophysics, 12 (1). 61-72.

Need more information?

Please contact Dr David Gunn for more information

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Photo by Marc Szeglat on Unsplash

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