Geotechnical engineers work in these two worlds: a theoretical world where ideas and events can be represented by numbers and calculated to as many decimal points as one desires, and a practical world where observations and events can only be described in general qualitative terms. The end product of instrumentation and monitoring, numerical data, provides a quantitative link between the two worlds

Professor Ralph B. Peck, the father of the observational method in geotechnical engineering, recognized early in his professional career the importance of field instrumentation and performance monitoring in geotechnical engineering, and he did a lot to promote its use.

NGI's former expert on instrumentation services, Elmo DiBiagio, and a former student of Professor Peck, has assembled a list of case histories from NGI projects as one-page summaries to illustrate the importance and diversity of field instrumentation projects using selected case histories from the project files at NGI.

For each case cited the principal scientific, practical, and economic benefits of the monitoring program are pointed out, in the following one-page summaries:

  1. Measurement of strut load in a test trench excavated in stiff marine clay
  2. Braced sheet piled excavation in soft clay
  3. Large diameter in situ direct shear tests in soft clay
  4. Leakage during first filling of reservoir at an embankment dam
  5. Rockfill dam with a core of coarse gravel and bitumen
  6. Trial embankment on soft sensitive clay
  7. Stability of a deep slurry trench in soft clay
  8. Concrete retaining structure for bulk storage of granular material
  9. Settlement of a gravity anchor in 460 meters of water
  10. Zoned rockfill dam with inclined core of moraine till
  11. Monitoring contact pressure at rock/ice interface beneath a glacier
  12. Long term behaviour of an offshore gravity base structure
  13. Measurement of dynamic avalanche parameters
  14. Large scale offshore soil penetration test in 220 meters of water
  15. Rockfill dam with central core of asphaltic concrete
  16. Model test of a suction anchor in soft clay
  17. Monitoring stresses in North Sea pipelines
  18. Ormen Lange Piezometers
  19. An early warning system (EWS) for detecting rock falls
  20. Observational method applied to a large tailings dam
  21. Crack detection in a steel girder bridge
  22. Model tests of a torpedo drop anchor in deep water
  23. Pre-piling of foundations for offshore wind turbines
  24. Heave and pore pressure in swelling clay at an offshore site