Subsurface Characterization of Coastal Deposits using Measurement While Drilling

Abstract

Measurement While Drilling (MWD) is a promising in situ test method that has gained increasing popularity in recent years. MWD can continuously characterize the subsurface while drilling any type of borehole in soil or rock without interfering with normal drilling operations. The latest MWD equipment gathers real-time data on numerous parameters that capture all aspects of the drilling process (e.g., depth, down thrust, rotation, torque, mud flow, and mud pressure). This paper summarizes MWD assessments performed in the coastal deposits of New Hampshire, USA. Profiles of individual and combined drilling parameters were used to differentiate between different soil layers and characterize subsurface conditions in complement with conventional, standardized geotechnical testing (e.g., SPT, CPTU) performed at adjacent boreholes. The results from this experimental campaign demonstrate the applicability of MWD systems to evaluate a broad range of geological conditions, from granular soils with erratic boulders to sensitive clays.

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