Prediction of Dynamic and Final Vertical and Horizontal Movements Due to Longwall Mining

Accurate prediction of dynamic mining subsidence is a critical factor in mitigating the disturbance of surface structures due to underground mining and therefore paramount for sustainable longwall mining practices. This paper presents an application of the Knothe influence function for predicting final and dynamic movements due to underground coal mining operations. Measured surface movements related to a single longwall panel located in the eastern U.S. are used to develop site-specific empirical parameters for subsidence prediction models with respect to final and dynamic movements in both the vertical and horizontal planes. Model calibration results for final deformations show that some of the empirical parameters derived for the specific site deviate from regional default values. Calibration tests for dynamic movements were conducted for points close to the panel edge, which are affected by the edge effect, and points in the middle of the panel, which are not. These yielded different time factor constants. Calculated deformations match measured data very well, which indicates that the Knothe formulation is applicable to modeling both final and dynamic deformations. The subsidence models developed for final and dynamic deformations were used to predict final and dynamic horizontal displacements at the site. The relative root mean square error of these predictions is rather high, which suggests that such predictions may be affected by other factors. However, specific portions of the prediction profiles display very low error. In addition, the displacement magnitudes are low, and the prediction model identifies the transitions in the displacement curves.