The Research Of Freeze-thaw Rock Damage Characteristics

With the increasing of cold regions construction, there have been a series of frozen rockproblems, the current study on frozen rock are inadequate. And most researches are still aboutsingle factor, but the rock influenced by several factors simultaneously due to the complexityof the actual project environment, the study of changes in the mechanical properties of coldregions rock under multi-factors coupling participation is particularly important. In this thesis,the actual cold regions engineering was taken as background, and based on the experimentresearch, the mechanical properties and mechanism of damage evolution under couplingaction of rock in different freeze-thaw cycles and confining pressure were systematicallystudied by taking the method combing the theory with numerical tools.The new red sandstone rock was taken from the construction site, and processed intostandard specimens, then conduct triaxial compression test under different number offreeze-thaw cycles (0times,5times,10times,20times,40times,60times) and differentconfining pressure (0MPa,2MPa,4MPa,6MPa) after the rocks were grouped by measuringdifferently longitudinal wave velocity, and the change laws of its strength and deformationcharacteristics of freeze-thaw cycles and confining pressure were analyzed combined withexperimental data.From a macro perspective of damage mechanics, the rock damage was seen as twostages based on the freeze-thaw cycles rock triaxial compression test results, the first stage isthe damage caused by the freezing and thawing cycles, and the second stage is the totaldamage caused by the common function of freeze-thaw cycles and the triaxial compression,thereby, the rock damage evolution equation and damage constitutive under the commonaction of single loads and freeze-thaw loads were established. The damage constitutive modelof rock was verified by the room temperature triaxial and freeze-thaw cycle compression testdata and the model parameters were discussed. The rationality of the model proved by that theresults show that the model can be a very good response of the mechanical properties of redsandstone damage.