April 7, 2021 ITS Money: Jean Benoit, Ph.D.

Jean Benoit, Ph.D. | University of New Hampshire

Ground Characterization using Monitoring While Drilling

A technique known as Monitoring While Drilling (MWD) makes use of the mechanical response of a drill rig and cutting tools while advancing a borehole. This presentation describes a typical MWD system, introduces basic interpretation of the measurements and discusses a case study in argillite bedrock where MWD was used to support the opinion that the existing rock was stronger than originally expected based on traditional rock quality from RQD and core logging alone.  This led to a 50% savings in length of caissons for this deep foundation project.

Findings

• MWD is an in-situ test and can easily detect stratigraphic changes in soils and in rocks, thin layers, fractures (it can differentiate between natural and drilling/driller induced) and rock quality.
• MWD can be used in any geologic context – no limit of applicability.
• MWD is easily implemented and can lead to more economical site investigation and design (better data, easy acquisition, rapid and independent of driller).