Assessment of dynamic response and stability of an abandoned room and pillar underground lignite mine

National Institute of Disaster Management (NIDM);American Society of Civil Engineers (ASCE)12th International Conference on Computer Methods and Advances in Geomechanics 2008 -- 1 October 2008 through 6 October 2008 -- Goa -- 93907The authors have been involved with some abandoned mines in the Tokai Region of Japan and they have been investigating their performance and responses in the long term and during earthquakes. In this article, some examples of stability problems observed in areas of abandoned lignite mines during earthquakes are summarized. Two-dimensional model tests of abandoned room and pillar mines are described and vibration characteristics and instability modes are briefly presented. Ground amplification is investigated at abandoned mine sites by using a series of finite element analyses. In the remaining part of the article, three-dimensional elasto-plastic dynamic stress analyses are presented. In numerical solutions, analyses are performed by using harmonic ground motions. It is found that the ground motions with low amplitudes may also cause significant damage in the surrounding mass around the mine and ground surface, depending on rock mass properties