In response to the effect of freeze-thaw cycles on fractured rocks in the western cold region project,a TDS-300 freeze-thaw testing machine was used to conduct freeze-thaw cycle tests on single fractured red sandstone.The fracture dip angles were selected as 0°,45°,and 90°,and the number of cycles was set to 0,20,40,and 60.A servo universal testing machine was used to conduct uniaxial compression tests on the red sandstone after freeze-thaw damage,and nuclear magnetic resonance(NMR)technology was used to detect the freeze-thaw damage characteristics of the red sandstone.The test results show that as the number of freeze-thaw cycles increases,the elastic modulus,mass,peak strength,and porosity damage variables of red sandstone show varying degrees of increase.Through NMR technology,it is found that the spectral area increases with the number of freeze-thaw cycles,while the development of small pores is slow,and the development of mesopores is rapid in the early stage compared to the later stage,while the number of large pores increases the most.In addition,as the number of freeze-thaw cycles increases,the white spots in the NMR image diffuse from the edge to the center increase,and the damage area gradually enlarges,deepening inward.Based on fracture mechanics,a compression shear fracture criterion for single fractured red sandstone was established under coupling effect of freeze-thaw and load,and the relationship between the compression shear coefficient and the number of freeze-thaw cycles was clarified,as well as the relationship between the compression shear coefficient and the fracture dip angles.This study can provide a theoretical support of disaster prevention and reduction for exploring the mechanical behavior and mechanism of fractured rock masses in cold regions.
Freeze-thaw damageFreeze-thaw cycleSingle fractured red sandstoneNMRCompression shear fracture
维普
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