Adjusting the influence function method for subsidence prediction

The extraction of ore and minerals by underground mining may induce ground subsidence phenomena. These phenomena produce several types of ground movement like horizontal and vertical displacements, ground curvature and horizontal ground strain at the surface, and associated building damage in urban regions. The influence function is a well-known and efficient method for the prediction of these movements, but its application is restricted to mining configurations with the same influence angle around the mine. However, this angle may display different values when the mine is not horizontal or when other subsidence events already occurred near the considered mine. In this paper a methodology and an algorithm are developed, based on the traditional influence function method in order to take into account different influence angles. This methodology is implemented in the Mathematica software and a case study is presented with data from the Lorraine iron mine field in France. Ground movements calculated with the developed methodology show a fair concordance with observed data.