Study on the viscoelastic-plastic fractional creep model of sandstone in uniaxial compression
In order to establish a creep model with few parameters,simple calculation and accurate de-scription of the creep process,based on rock mechanics and fractional order theory,fractional-order soft components were introduced and combined with elastic,plastic and viscous components,and an innovative viscous model was obtained.The elastic-plastic creep model was used to derive the constitutive equation of the creep model,and the parameter identification and curve fitting and comparative analysis were per-formed on the sandstone uniaxial compression creep test data,and then the model was verified.The results showed that the strain of the introduced fractional-order soft element increases with time as a power func-tion,which can characterize the nonlinear creep stage.The creep process of elastic element,plastic ele-ment,viscous element and fractional-order soft element was analyzed in detail.The constitutive equations of the model under three different conditions (ε)(t→∞)=0(σ<σs),(ε)(t→∞)>0(σ<σs),(ε)(t→∞)>0(σ≥σs)and the parameter identification method with simple calculation were derived,and the fitting de-gree of the fitting curve of the test data was above 0.9.The rationality and scientificity of the creep model were verified.The established six-parameter viscoelastic-plastic fractional order model could comprehen-sively describe the whole process of creep,and compared with other models,the model required fewer parameters and less computation.
万方数据
维普
