Analysis of coal pillar stability(ACPS): A new generation of pillar design software

Thirty years ago, the analysis of longwall pillar stability(ALPS) inaugurated a new era in coal pillar design.ALPS was the first empirical pillar design technique to consider the abutment loads that arise from full extraction, and the first to be calibrated using an extensive database of longwall mining case histories.ALPS was followed by the analysis of retreat mining stability(ARMPS) and the analysis of multiple seam stability(AMSS). These methods incorporated other innovations, including the coal mine roof rating(CMRR), the Mark-Bieniawski pillar strength formula, and the pressure arch loading model. They also built upon ever larger case history databases and employed more sophisticated statistical methods.Today, these empirical methods are used in nearly every underground coal mine in the US. However,the piecemeal manner in which these methods have evolved resulted in some weaknesses. For example,in certain situations, it may not be obvious which program is the best to use. Other times the results from the different programs are not entirely consistent with each other. The programs have also not been updated for several years, and some changes were necessary to keep pace with new developments in mining practice. The analysis of coal pillar stability(ACPS) now integrates all three of the older software packages into a single pillar design framework. ACPS also incorporates the latest research findings in the field of pillar design, including an expanded multiple seam case history data base and a new method to evaluate room and pillar panels containing multiple rows of pillars left in place during pillar recovery.ACPS also includes updated guidance and warnings for users and features upgraded help files and graphics.

Development of a new algorithm for implementing the edge effect offset for subsidence calculations

The surface deformation prediction system(SDPS) program has been developed as an engineering tool for the calculation of subsidence deformation indices through the implementation of various prediction methods.From basic user-defined input parameters, SDPS can determine subsidence indices, such as mining induced displacements, strains, tilt, etc., at any elevation between the seam and the horizontal or varying surface topography.A fundamental parameter in obtaining reliable ground deformation results is the determination of the edge effect offset.The value assigned to the edge effect offset corresponds to a virtual offsetting of boundary lines delineating the extracted panel to allow for roof cantilevering over the mined-out area.The objective of this paper is to describe the methods implemented in updating the edge effect offset algorithm within SDPS.Using proven geometric equations, the newly developed algorithm provides a more robust calculation of the offset boundary of the extracted panel for simplistic as well as more complex mining geometries.Given that an extracted panel is represented by a closed polyline, the new edge offset algorithm calculates a polyline offset into the extracted panel with respect to the user defined edge effect offset distance.Surface deformations are then calculated using this adjusted panel geometry.The Matlab program was utilized for development and testing of the new edge effect offset algorithm.After completing rigorous testing regimes, the new offset algorithm will be integrated into SDPS further increasing the speed and reliability of the program resulting in a retrospective increase in capability and flexibility.

Development of a web-platform for mining applications

‘‘Web ground control"(web GC) provides users with instantaneous access to mine design applications anywhere, at any time, through a web browser.Utilizing a web-based multiple-tier architecture, users are able to easily access ground control designs, perform on-demand calculations in the field, as well as facilitate project collaborations across multiple users, devices, and operating systems.Currently, the web GC platform contains five ground control related design applications previously developed and distributed by the US National Institute of Occupational Safety and Health(NIOSH), that is, analysis of roof bolt stability(ARBS), analysis of longwall pillar stability(ALPS), analysis of retreat mining stability(ARMPS), analysis of retreat mining stability–highwall mining(ARMPS-HWM), and analysis of horizontal stress in mining(AHSM).With respect to design decisions made by the web GC development team, the web GC platform will be able to further integrate future mine design applications providing the mining industry with one of a kind umbrella suite of ground control related software available at ones fingertips.The following paper provides a detailed overview on the current state of the web GC platform with discussions ranging from back-end database development and design to the front-end user-platform interface.Based on current progress in platform development as well as beta testing results, the web GC platform is scheduled for release in the fall of 2018.