冻融循环作用下的建筑灰岩风化特性演变OA

Freeze-thaw cycles are among the primary factors affecting the limestone cultural relics in northern China.These cycles often result in various forms of surface weathering,seriously threatening the long-term preservation of these cultural relics.Water immersion freeze-thaw simulation weathering experiments were conducted on fresh limestone.The development patterns of physical and mechanical property indicators were obtained by utilizing various characterization techniques.By examining variations in pore structure,the freeze-thaw damage mechanism of limestone was quantitatively revealed from both macro and micro scales,and a comprehensive evaluation of weathered limestone was performed using an entropy weight-linear weighting method.The results have shown that after 50 freeze-thaw cycles,the P-wave velocity and surface hardness significantly decrease,with a loss rate of over 10％.The capillary water absorption coefficient increases by more than one time;The uniaxial compressive strength decay rate was 30.6％.As the number of cycles increases,the structural integrity of the compressed limestone becomes worse.The pores of limestone are primarily composed of mesopores(0.1-1 000.0 μm).Freeze-thaw cycles lead to an increase in both the number and volume of pores,accompanied by particle wear and the expansion of cracks.The mechanical-property half-life is a key parameter for evaluating limestone's freeze-thaw resistance.A multivariate regression model based on non-destructive measurements can effectively predict the variation in uniaxial compressive strength.The capillary water absorption coefficient exhibits the greatest sensitivity to weathering damage.The introduction of an integrity index enables a multidimensional and quantitative assessment of the weathering severity of building limestone.The research findings provide a theoretical basis and practical guidance for the scientific understanding of limestone materials and the assessment of the current state of cultural relics'weathering.