Measurement-while-drilling (MWD) technology is used to collect and record drilling parameters with depth during subsurface site investigations. The MWD sensors are attached to the drilling rigs and a data acquisition system collects the measurements from the sensors and transmits the data to the surface in real time. These parameters include penetration rate, depth, operational torque, downward pressures, auger rotation speed, flushing fluid properties, flow rate and volumes.
The proposed scope aims to outfit a North Carolina Department of Transportation (NCDOT) drill rig with MWD sensors and develop protocol and data reduction methods to support NCDOT geotechnical exploration and site characterization programs. This proposed scope is in concert with the FHWA A-GaME vision and will serve to improve the collection and interpretation of subsurface geotechnical data.
The proposed tasks include Literature Review, Procurement of Sensors and Rig Selection, Support of the Installation and Functionality Testing Effort, Participation in Field Testing and Sample Retrieval with NCDOT Staff, Performance of Laboratory Testing Program, and Data Analyses and Reporting. Improving subsurface geotechnical data collection through MWD data collection offers several benefits including the following:
i. The use of the higher resolution stratigraphy data to minimize surprises arising during construction and therefore reduce costly and time-consuming construction change orders;
ii. Enhancing the accuracy of engineering property assessments for subsurface layers by supplementing in-situ and laboratory data with interpreted MWD data;
iii. The utilization of the data to assess the potential of fewer required exploration locations; and,
iv. The possibility of using the MWD data in design of driven pile and drilled shaft foundation systems while enabling the use of higher resistance factors for foundation design, potentially reducing costs.
v. Additionally, MWD implementation provides guidance on optimal drilling equipment choices for specific geologic formations, resulting in shorter drilling times, reduced expenses, and improved productivity.
The research project will yield key deliverables including a comprehensive list of necessary sensors for collecting drilling parameters, the identification and integration of MWD sensors into one of NCDOT's drill rig, detailed documentation of the installation process, and field and laboratory data collected in association with the monitored MWD data. A final report will summarize the data analyses approaches and the most suitable data reduction correlations between properties of soils derived from both laboratory experiments and fieldwork and the MWD drilling parameters.
