Characteristics Of Time-dependent Creep Deformation For Brittle Rock In Compression

The thesis,based on time-dependent creep deformation instability of brittle rock under high in-situ stress as the research background,considering time-dependence of rock damage process,introducing time-dependent creep constitutive equation of rock at a meso-scale,establishes a numerical model of rock failure process considering the time-dependent effect of rock,and applies the model to simulate uniaxial creep failure process of brittle rock under the constant loads.The numerical simulation result shows three typical creep deformation stages,which are the primary creep stage,secondary creep stage and tertiary creep stage of the rock creep process respectively.And then,compared the simulation results with the laboratory test observed in laboratory,they agree well with each other,which means that the theory proposed in the paper can simulate the uniaxial creep test process.To simulate constant strain rate biaxial test,single-stage stress and multi-stage stress test under biaxial creep test,we got the numerical simulation of the three test methods for specimen failure mode and carried out the comparative study,to find that effect of stress load on the failure mode by simulation is fit well with laboratory tests,verifying that the theory can be used to simulate the biaxial creep experimental process.And the result of simulation shows that,under biaxial creep experiment,the produced number of acoustic emission,the average size of the released energy represented by a single acoustic emission number and tensile stress or shear stress as a leading role,performs strongly regularityly in the evolution process of micro-cracks generation,expansion and penetration,these laws of which provide a more intuitive understanding for the creep time-dependent deformation process of brittle rock.Finally,the model was applied to simulate rock tunnel deformation,numerical simulation and analysis results indicate that this model can not only simulate the tensile-shear stress concentration areas around tunnel,and also can be used to be a reference for the location prediction of the damage to tunnel,which has important theoretical guidance and practical significance for the long-term stability of the numerical simulation for the project research.