Establishment Of Damage Constitutive Model Based On Unified Strength Theory Of Rock And Numerical Test Research

Rock mass is a complex and ubiquitous medium,its stress and failure process is directly related to the safety and integrity of the whole structure,therefore,it is of great theoretical and practical significance to study the mechanical properties during the deformation process.In this study,the strength of rock elements is assumed to obey the unified strength criterion,combined with the Weibull random distribution function and the influence coefficient of intermediate principal stress b=1/4,the damage and failure constitutive model of rock under uniaxial loading based on the unified strength criterion is established,and the new damage constitutive model is fitted to the real test data,then,in order to facilitate the application of rock damage constitutive model,based on Fortran language,it is embedded into ABAQUS main program through UMAT user subroutine interface to realize its numerical value.The uniaxial compression tests are systematically studied by means of laboratory test and numerical simulation.The specific research contents and results are as follows:（1）Based on the Weibull random distribution function and the assumption that the strength of rock elements follows the unified strength criterion,a damage constitutive model of rock based on the unified strength criterion is obtained.The effect of intermediate principal stress is ignored in the conventional damage constitutive model,and the intermediate principal stress is considered in the unified strength criterion?₂,It is a theory that can reflect the whole stress state of geotechnical material.The model has fewer parameters and clear physical meaning,and can be easily established and calculated.It provides a reference and practical significance for the study of damage constitutive model of rock materials.（2）By the Weibull distribution parameter₀F and m,the curve of the relationship between the damage variable and the cumulative strain in uniaxial state is obtained by calculating the damage variable D,and it is shown that the total damage increases with the increase of strain,and finally the total damage value tends to 1.The new constitutive model was fitted to the real test data,and the fitting correction coefficient R was greater than 0.99.It is verified that the damage constitutive model of rock is scientific and reasonable.（3）In the custom material interface program of ABAQUS,using Fortran language to develop the model,the numerical simulation results are compared with the experimental results in terms of stress-strain curve,plastic strain characteristics,stress distribution and failure state,the simulation results can validate the indoor test results,verify the correctness of the numerical simulation and the applicability of the constitutive model.Figure 31 Table 5 Reference 74...