Sensitivity analysis of a dynamic subsidence prediction model for longwall extraction

Surface ground deformations due to mining are dynamic in nature and depend, among others, on the rate of mining.There are many formulations that can calculate and predict ground deformation due to mining.The majority of these models can accurately predict final deformations, i.e., maximum deformation values at specific surface points.In many instances, dynamic deformation values need to be considered, especially when undermining surface structures that are sensitive to subsidence, differential displacements, and/or tilt.This paper discusses subsidence development (dynamic subsidence) over a longwall excavation in the eastern US, which was recently completed.Measurements include x,y,z coordinates of a number of points (stations) over the longwall panel, which were monitored over a period of time while mining the panel.Dynamic subsidence was modeled for each of these surface points using an empirical formulation based on the influence function method as implemented in the Surface Deformation Prediction System (SDPS) package.Results show that the location of each surface point with respect to panel boundaries affects the calculation of dynamic subsidence values.A sensitivity analysis was completed for some of the parameters that influence dynamic subsidence calculations.These parameters include the edge effect offset and the time factor.