Numerical simulation of the factors causing land subsidence due to overexploitation of the aquifer in the Amyntaio open coal mine, Greece

Abstract

The land subsidence due to the overexploitation of the aquifer has slowly affect extensive area, causing significant damage. In the Amyntaio sub-basin during the last decades the aquifer has been overexploited by both the draining wells of the Amyntaio open pit coal mine and the irrigation wells, resulting to the activation of land subsidence. This phenomenon extends intensively 4 km around the mine causing damage to the villages of Anargiroi, Valtonera and Fanos. The intensity of this phenomenon is not the same and depends on geological, tectonic and hydrogeological conditions. To simulate the failure mechanism as well as to predict the future deformations at these villages, numerical models were established using the Plaxis three-dimensional finite element code. The correlation of these analyses with the field observation is extremely high. Furthermore, in order to evaluate the influence of triggering factors such as the geotechnical parameters, the offset and the angle of the faults and the groundwater withdraw on the magnitude of the vertical differential deformations, three parametric simulation scenarios were performed for each village. These analyses lead to useful conclusions about the causal factors of this phenomenon and clarify the main causes of region-to-region variation. Keywords: Natural hazards, Land subsidence, Finite element simulation, Overexploitation of the aquifer, Three-dimensional consolidation