Improved Methods of Rock Tunneling in Excavation

REU: Underground Infrastructure REU | AUTHOR: Charles Hruda​ – Embry-Riddle Aeronautical University

MENTOR: Rennie Kaunda – Colorado School of Mines

ABSTRACT

Microwave influence on rock breakage has been thoroughly explored in the mining community as a cheaper, more efficient method to assist mechanical tunneling. Exposure to microwave energy can reduce rock strength; however, a mathematical method of quantifying the reduction of strength prior post-irradiation testing has not been created. This project aimed at laying the foundation for developing a method relating power absorption and rock strength. Through literature review, it was found that mineralogy and material makeup are key components for both power absorption and rock strength. Laboratory testing of eight collected rock samples was conducted by measuring acoustic velocities prior to microwave irradiation. During irradiation, the power level was the only parameter that was changed between the samples, while irradiation time was constant. After being exposed to microwave energy, the temperature of each of the samples was recorded, then acoustic velocity tests repeated. An analysis of the results showed that an increase in the power level of microwave energy the rock was exposed to correlated with a larger decrease in p-wave velocities, an indicator that the UCS of the rock will decrease more as it is exposed to increasing amounts of microwave energy.

AUTHOR BIOGRAPHY

Charles Hruda is a rising junior, majoring in Civil Engineering at Embry-Riddle Aeronautical University in Daytona Beach, Florida. At Embry-Riddle he was briefly introduced to the research world as a sophomore, where he worked with upperclassmen on a traffic engineering project, collecting and sorting data from a Bluetooth tracking device. This summer was his first extended experience in research, conducting literature reviews, designing experiments, organizing, and analyzing data, all focused on the influence of microwave energy on rock strength. He plans to finish his research experience by writing a comprehensive report of his time, hoping that his work can serve as the foundation for another student to finalize the project.