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Abstract Based on the mechanical investigation，a coupled elastoplastic damage model is proposed to simulate the mechanical behaviour and damage evolution process of the intact deep granite in Beishan area. The experimental results revealed that Beishan granite exhibits typical brittle failure mode under low confining pressure. With the increase of confining pressure，the brittle-ductile transition of the mechanical behaviour took place；and significant plastic deformation and volumetric dilatation are noticed. The damage evolution process is also analyzed according to the initiation and propagation characteristics of the stress-induced microcracks. It is indicated that the failure and nonlinear mechanical behaviour of Beishan granite are essentially related to the coupling effect between the damage and plastic deformation. Based on this acknowledgement，a coupled elastoplastic damage model is proposed. In the model，a non-associated plastic flow rule is used to describe the compression-dilatation transition of the volumetric deformation. The coupling between the damage and plastic deformation is realised by introducing the independent damage variable in the plastic yield surface. The comparison between the predictive result and experimental data suggests that the proposed model is capable to reproduce the main mechanical performances of Beishan granite under compressive stress condition，especially the brittle-ductile transition of mechanical behaviour with the increase of confining pressure.
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Received: 25 July 2012
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2013, Vol. 32 
