Ground penetrating radar technique to locate coal mining related features: case studies in Texas
Save, Neelambari R
MetadataShow full item record
The goal of this research project is to identify the efficacy of the ground penetrating radar (GPR) technique in locating underground coal mine related subsidence features at Malakoff and Bastrop, Texas. The work at Malakoff has been done in collaboration with the Railroad Commission of Texas (RRC). RRC has been carrying out reclamation of abandoned underground coal mines at Malakoff since the early 1990??s. The history of the specific mining operations (at Malakoff and Bastrop) that took place in the early 1900??s has been difficult to ascertain; therefore, the use of a geophysical techniques like ground penetrating radar to identify hidden voids and potential subsidence features is vital for future reclamation process. Some of the underground mine workings at the field site have collapsed over time affecting the topography by creating sinkholes. GPR data, employing 25 MHz, 50 MHz and 100 MHz frequency antennae, have been collected in common offset patterns and azimuthal pattern. GPR data indicate the mine tunnels possibly connecting existing sinkholes by radargram hyperbolae that correspond with mine openings observed visually or during reclamation. This study also denotes the importance of understanding the variable physical properties of the stratigraphy, which could lead to false alarms by misinterpretation of the radar signals. Natural and man-made above-ground structures cause obstructions in data collection, and hence an optimal design is required for each survey. RRC successfully ground-truthed the data during its reclamation process. In turn, the acquired geophysical data helped to guide the reclamation. At Bastrop, GPR data along with historical documentation led to the conclusion that coal mining did exist in this region but is not a major concern to the immediate stability and safety of the field site. It can be concluded from both the studies that the GPR technique identifies anomalous shafts/tunnels possibly connecting potential failure.