Prediction and monitoring of subsidence hazards above coal mines (Presidence)

Mining subsidence engineering is one of the most important topics in relation to coal mining. Although its occurrence, prediction and control are well known, this project will apply various innovative techniques to an old problem (photogrammetry, InSAR, GPS, seismic tools, SFS). Geology is a major factor in surface subsidence. Empirical predictions are inaccurate where experience is lacking and geology unusual. Geomechanical subsidence modelling can account for geology but requires anisotropic solutions to reproduce subsidence profiles. Four items have been developed in relation to the prediction of subsidence caused by underground infrastructures: two in relation to shafts (telemetry and instrumentation for fill stability, and the laser-scanner techniques for surveys); another in relation to a survey methodology using numerical modelling for infrastructure roadway, and the last one in relation to the effect of mine water on concrete and other materials. A 4D database, called GeoMond-DB has been developed to manage subsidence hazards on the surface, working with data from Germany, Poland and Spain. A methodology based on geomechanical models to establish a prevision of surface and subsidence was carried out and validated. Specially, the consistency of FLAC 3D was checked to evaluate subsidence and the tensile strain on the surface. In conclusion, the techniques employed in this research represent a significant advance on the current situation in forecasting and control of subsidence. Therefore, although some of the investigated techniques must still be refined, it can be said that the results of this research project will have a positive effect in the monitoring of the subsidence in the coal basins of the EU and some outcomes, such as the technique of monitoring the movements of the ground with a GPS and vibrating sensors, could be exported outside the EU.