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Abstract The mechanical properties of jointed rock mass are closely related to its occurrence of stress state. None of the existing methods in obtaining representative elementary volume has taken the effect of confining pressure on representative elementary volume(REV) size into account. Based on certain road tunnel project，this issue is studied with 3D discrete element method in this paper. The dominant joint sets of rock mass are calculated based on a large number of joint surveys in our study area. Then，the structure model and 3D discrete element model of rock mass are built，which are further employed to simulate the compression test of rock mass，thereby employing the effect of confining pressure on REV size，deformation and mechanical properties of rock mass. The results indicate but not limit to the following conclusions：when confining pressure is less than 20 MPa，REV size is positively correlated with the increase of confining pressure；when the confining pressure is greater than 20 MPa，REV size keep constant；when the confining pressure is less than 60 MPa，the capacity of rock mass is positively correlated with the increase of confining pressure；when the confining pressure is greater than 60 MPa，the rock mass capacity did not change as the confining pressure increasing. In addition，the axial strain，lateral strain and volumetric strain also showed significant effect of confining pressure.
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Received: 14 July 2010
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2011, Vol. 30 
