The Improvement And Application Of The New Constitutive Model Considering Creep Damage And Damage Healing For Salt Rock

In recent years,many scholars put forward kinds of creep damage models,including a comparatively mature theory namely phenomenological analysis.In this theory,the continuum damage mechanics was applied to the rheological mechanics.Introducing damage to rheological model of salt rock,formation damage was expressed by the damage variabl,and the evolution of damage was described by the damage evolution equation.The coupling effect on the creep damage was studied with this method.However,many models are not involved damage recovery phase.In this paper,based on the previous creep damage constitutive model,the creep-damage theory and calculation method of the salt rock were improved by considering damage healing and a systematically comprehensive creep-damage model was achieved.Firstly,through the data analysis of the creep damage properties and damage healing features getting from uniaxial and triaxial tests,the regulation of creep damage and damage healing were summarized.Secondly,analyzing the previous creep damage constitutive model,a new model considering damage healing?userc_dh model?was put forward.The model was verified by the existing research results on creep damage-recovery test of salt rock,and material parameters were obtained through the regression analysis.Using the secondary development function of FLAC^3D,writing the user-defined constitutive model,Numerical analysis method was used to simulate the triaxial creep damage-recovery test of salt rock small specimen,which proved the validity of the program.In the end,the developed userc_dh model and the userc_d model?creep damage model?were respectively applied to the research on rheological damage-recovery of salt rock repository,in order to analyze the deformation and damage distribution area of the salt rock cavern.Comparing the results,it found that the creep rate of the userc_dh model was decreased obviously when unloading;in addition,the damage area of the cavern cavity is reduced from the macroscopic point of view.The userc_dh model more practical describes the creep damage-recovery features of salt rock,which is very helpful for maintaining the stability of the cavern.This model is a creative contribution to the formation mechanics and engineering theory in our country.