冻融循环作用下砂岩物理力学特征研究OA

In high-altitude cold regions,porous rock masses undergo long-term freeze-thaw cycles,causing significant changes in their physicomechanical properties and may consequently trigger a se-ries of geological and engineering problems.To investigate the changes in physicomechanical proper-ties and damage evolution patterns of porous rock masses under repeated freeze-thaw cycles,typical sandstone was selected as the research object.Long-term freeze-thaw cycle experiments were con-ducted to systematically analyze the variation patterns of its physical properties,and uniaxial com-pression tests were performed on sandstone specimens subjected to different numbers of freeze-thaw cycles.The variation patterns of key physicomechanical indicators—including mass,porosity,P-wave velocity,elastic modulus,uniaxial compressive strength,and peak strain—were examined in detail.The results showed that:① during freeze-thaw cycles,the dry mass and P-wave velocity of sandstone both showed a gradual decreasing trend,while porosity exhibited a three-stage increase.② Under different numbers of freeze-thaw cycles,the stress-strain curves of sandstone were divided into four stages:compaction,elastic deformation,plastic deformation,and failure.As the number of freeze-thaw cycles increased,the compaction stage progressively lengthened,while the elastic defor-mation stage shortened accordingly.③ With increasing freeze-thaw cycles,both peak strength and elastic modulus followed a two-stage degradation pattern,characterized by an initial slow decline fol-lowed by a rapid decrease,while peak strain showed an overall increasing trend.Moreover,the strain variation during the compaction stage was consistent with the trend of porosity change.These findings provide a theoretical basis and reference for engineering construction in high-altitude cold re-gions.