The Subtropolis Mine is a room-and-pillar mine extracting the Vanport Limestone (Allegheny Formation, Pennsylvanian System) near Petersburg, Ohio. The rooms are nominally 40 ft. wide and 16 ft. high. In February of 2018, mine management began implementing a new mine layout to better control the negative effects of excessive levels of horizontal stress.
‘Stress Control’ mine layouts evolved at mines suffering from strata instabilities, resulting in experiments utilizing methods to mitigate adverse impacts. Jack Parker was able to write about personal experiences at the White Pine mine in Michigan and formulate a basic framework for the ‘stress control layout’. Various research at the USBM, MSHA, and NIOSH have studied its effectiveness over a wide range of geologic conditions. While this design approach has proven successful in many categories, it is difficult to implement and can concentrate stresses in crosscuts.
To help better understand these issues, NIOSH and East Fairfield Coal Company are cooperating on a research project at the Subtropolis Mine. This project consists of detailed in-mine mapping in conjunction with state-of-the-art 3D Dynamic LiDAR scans by Mine Vision Systems. These methods are being used to determine the efficiency and effectiveness of this engineering intervention towards lowering potential injuries from strata instabilities.