Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Mining Engineering

Committee Chair

Brijes Mishra

Committee Member

Yi Luo

Committee Member

Qingqing Huang


Ground failure is a major contributor of the total fatalities in underground mines in the US. Underground coal mines in the Northern Appalachian region have weak roof rock mainly composed of shale and sandstone. Characterization of shale is indispensable for developing an effective ground control plan. However, this has not been done extensively. This thesis attempts to address this issue. It investigates the variation in mechanical properties of shale with variation in size. In addition, an attempt has been made to relate the strength of shale with its petrographic parameters. X-ray diffraction technique was used to estimate the compositional parameters like quartz content, calcite content and clay content. Similarly, scanning electron microscopy was used to image the rock sample at microscale and estimate grain properties such as grain size, grain shape and grain orientation. Statistical analysis was performed to identify the extent of correlation between these parameters and strength and size of sample. From the analysis, it was observed that there was a significant difference in the strength of the sample with variation in size. In addition, samples with high quartz and calcite content showed higher average strength. Grain parameters also played a major role in influencing the strength of the sample with samples having higher average grain size inclining to have lower strength. Grain shape when defined by aspect ratio correlated with the strength of shale with higher aspect ratio contributing to higher strength. Grain orientation did not have any impact on strength. Finally, this research will help in understanding the size effect phenomenon in mines by looking into shale rock at microscopic scale and analyzing its petrographic parameters.