Ground Surface Subsidence Risk Assessment by Underground Mining in Estonia

The paper deals with risk assessment/management problems in Estonian oil shale mines, where room-and-pillar mining with blasting is used. The primary interest of this study concerns evaluating the usability of the applied risk assessment method at room-and-pillar mining. The study addresses risk associated with the collapse of mining blocks and resulting surface subsidence. Some of the various factors, relevant to Estonian oil shale mines, have been determined. For risk estimation the judgmental approach and event tree are used. Investigations in Estonian oil shale mines show that the likelihood of the surface subsidence is not acceptable. Mitigation methods will reduce the likelihood. The results of the investigation are of particular interest for practical purposes.