Rock damage constitutive model based on residual intensity characteristics under freeze-thaw and load

The deformation and failure characteristics of rock are the fundamental mechanics problems directly faced in a geotechnical engineering construction project in cold region. To simulate the whole process of rock deformation and failure under freeze-thaw and load,the rock micro-elements in the axial direction are abstracted into four parts:the un- damaged part,the freeze-thaw damaged part,the loading damaged part and the coupling damaged part of freeze-thaw and load,and the axial stress is supported by the four parts together,with the three damaged parts can share the resid- ual stress. Using the Weibull distribution to describe the heterogeneity of rock materials,the coupling effect of the freeze-thaw and load on the total damage is expressed quantitatively based on the D-P failure criterion,and the damage constitutive model based on the characteristics of the residual strength is established for freeze-thaw and loaded rock.In terms of rock deformation and failure characteristics,the theoretical expression of the model parameters is derived. To verify the rationality of the model,the freeze-thaw cycle and triaxial compression tests of the red sandstone is con- ducted,the law of rock deformation and failure is analyzed,the effects of freeze-thaw cycles and confining pressure on their mechanical properties are revealed. It is shown that the damage model reflects the whole process of deformation and failure of freeze-thaw and loaded rock,at the same time,the effects of freeze-thaw cycles and confining pressure on the deformation properties of rock can be characterized. The evolution path of total damage reflects the consistency of the micro-mechanical response and macroscopic characteristics of the deformation and failure of rock,and the nonlin- ear influence characteristics of freeze-thaw and load on total damage expansion is portrayed,the macroscopic mechani- cal effects induced by mesoscopic damage evolution are explored which can provide a theoretical basis for revealing the mechanism of rock freeze-thaw damage.