Improving the influence function method to take topography into the calculation of mining subsidence

The classic influence function method is often used in the calculation of mining subsidence caused by strati- form underground excavations. Theoretically,its use is limited to the subsidence predictions under the condition of hor- izontal ground surface. In order to improve the original influence function method to take topographic variations into ac- count. Due to real-world mining conditions that are usually complicated,it is difficult to separate topography influences from influences caused by other factors. The present work uses simplified numerical simulation models to analyze the topography influence only,avoiding the effects of other factors. Then several parameters of the influence function meth- od,including the influence radius,influence angle,and vertical subsidence coefficient,are adjusted by considering four correction factors with respect to the topography. They all can be defined as functions of the relative surface elevations with ore body. After this,the improved influence function method can well fit the numerical simulation results and field measurement data. Comparing to the original method,the improved method only takes the topography as additional in- put data. The method of constructing the simplified numerical simulation models can be used to solve the topographic correction factors under other mining and geological conditions.