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Abstract It is the purpose of this paper to discuss the problem of rock mass displacement and deformation due to deep underground mining of fractured thick iron orebody. The laws of ground surface subsidence and rock mass movement and deformation in north area of Guanzhuang iron mine due to deep underground mining are studied. The ground surface subsides continuously；and rock mass fails slowly in the mine. Based on the ground surface subsidence and surrounding rock deformation monitoring and numerical simulation methods，a comprehensive method is put forward to analyze the displacement and deformation mechanism of rock mass due to underground mining. Several measurement and analytical methods have been given for predictions and analyses of rockmass dispacements and deformations due to deep mining of fractured thick iron orebody. They are classified as meaurement methods(creep analyses，ground movements analyses，surrounding rock deformations analyses and in-situ stress measurements) and numerical methods(ANSYS and FLAC). New monitoring data have been analyzed to study the rock mass deformations due to deep mining of fractured thick iron orebody in Guanzhuang iron mine. It has also been compared to the results obtained by numerical analyses. By mechanical analysis as well as case study，rock mass deformation and ground subsidence caused by the deep iron ore mining are studied. The results show that the displacements of overburden layer are characterized by uniform and entire compression，displacements and deformations. The laws of surface subsidences are that the surface deformations are continual and slow with a long last period of movement. A case study shows that this method is an available approach to investigate the mechanism of rock mass deformation and ground surface subsidence.
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Received: 06 August 2009
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