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| Direct shear strength model of rock mass with coplanar intermittent joints |
| 1.State Grid Electric Power Research Institute， Nanjing NARI Group Corporation, Nanjing, Jiangsu 210003， China; 2.College of Water Conservancy and Hydropower Engineering， Hohai University， Nanjing, Jiangsu 210098， China; 3.Institute of Geology and Geophysics， Chinese Academy of Sciences， Beijing 100029， China； 4.Civil and Water Conservancy College， Tsinghua University， Beijing 100084， China) |
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Abstract According to theoretical analysis and model test, the direct shear strength behavior of rock mass with coplanar close intermittent joints was investigated. Through introducing deformation compatibility equation at normal direction, the direct shear strength formulation was deduced based on the MohrCoulomb theory. According to the complete stress strain curve obtained from model tests, there are five typical stages in the failure process with linear elastic increment, slippage of the joints, steady development of postcracking, the coalescence failure of discontinuous joints and the residual strength. The peak and residual strength are increased by the increase of normal stress with poor relationship between deformation property and normal stress. The peak strength decreases with the increase of the joint connectivity rate, and the drop velocity is slow at low connectivity rate. The joint distribution has influence on the strength of rock mass, and the strength of model with joints on edge is bigger than that of the model with joints in the middle. The theoretical calculation results are in good consistency with experimental results to give good description of the direct shear strength of rock mass with coplanar intermittent joints.
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2012, Vol. 33 
