(1. School of Energy and Safety Engineering，Hunan University of Science and Technology，Xiangtan，Hunan 411201，China；2. State Key Laboratory of Coal Resources and Safety Mining，China University of Mining and Technology，Xuzhou，Jiangsu 221008，China；3. Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines，Hunan University of Science and Technology，Xiangtan，Hunan 411201，China)
Abstract：The systematic study on the essence of creep strain has not been carried out at present. A method separating the viscoelastic-plastic strains and the techniques of data processing were proposed. The elasto-visco-plastic deformation characteristics of iherzolite at No.2 area in Jinchuan were studied. The instantaneous strain was decomposed into the instantaneous elastic and plastic strains. The instantaneous elastic response is nearly linear. The instantaneous plastic modulus increased with the increasing of stress. The creep strain was decomposed into the viscoelastic strain and the viscoplastic strain. The viscoelastic strain exhibited a creep reduction，while the viscoplastic strain exhibited the creep reduction，the steady creep，and even the accelerating creep. The viscoelastic strain，the viscoplastic strain and the steady creep rate are related to the deviatoric stress level nonlinearly. The visco-elasto-plastic strain characteristics of radial creep are similar to that of axial creep. But the radial creep strain is only 25%–30% of the axial creep strain. A new BNMC creep damage model was established by connecting the Burgers model with the nonlinear M-C plastic components in series. The accelerated creep was treated in the model as a stage that rock strength decreased rapidly and the viscoplastic deformation highly developed with the plastic instability. The BNMC creep damage model was written into FLAC3D via VC++ programming. The method of determining the unknown parameters in the creep damage constitutive model BNMC was proposed.
2016, Vol. 35 
