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通过研究砂岩试样在酸性Na2SO4溶液、中性Na2SO4溶液和碱性NaOH溶液中浸泡并经历冻融作用后的物理力学特征,分析了砂岩在不同化学溶液中腐蚀30d后及再经历不同冻融循环次数作用后其物理力学特征的变化规律,同时,借助于体视显微镜和SEM扫描电镜对试样微细观结构的损伤劣化进行了观察,并基于孔隙率的变化建立损伤变量来定量的描述试样的损伤劣化程度。试验结果表明:随着冻融循环次数的增加,浸泡在不同化学溶液中砂岩试样的峰值强度及其弹性模量均呈现出指数函数的劣化趋势,而其峰值应变却按指数函数的趋势增加。不同化学溶液下砂岩试样的损伤程度随着冻融循环次数的增加而逐渐加剧,酸性溶液下试样的损伤程度大于中性溶液和碱性溶液下的损伤程度,碱性化学溶液下试样的冻融损伤程度最小。酸性溶液加剧了冻融作用下砂岩试样的损伤劣化程度,而中性至碱性溶液下起冻融损伤程度却得到一定的缓解。化学腐蚀作用与冻融循环作用相互促进、共同影响着砂岩试样的损伤劣化程度。
By analyzing the physical and mechanical characteristics of the sandstone samples immersed in acidic Na2SO4 solution, neutral Na2SO4 solution and alkaline NaOH solution and subjected to freeze-thaw cycles, the sandstone samples were analyzed under different chemical solutions for 30 days and then underwent different freeze-thaw cycles At the same time, the damage and deterioration of the microstructure of the sample were observed by stereomicroscope and SEM scanning electron microscope, and the damage variable was established based on the change of porosity to quantitatively describe the sample Of the degree of damage deterioration. The experimental results show that with the increase of the number of freeze-thaw cycles, the peak strength and elastic modulus of sandstone specimens immersed in different chemical solutions show an exponential decay trend, while the peak strain increases exponentially . The damage degree of sandstone samples with different chemical solutions gradually aggravated with the increase of the number of freeze-thaw cycles. The damage degree of samples under acid solution was greater than those under neutral solution and alkaline solution. The samples under alkaline solution The degree of freeze-thaw damage is minimal. Acid solution exacerbated the freeze-thaw sandstone sample damage and deterioration, and neutral to alkaline solution freeze-thaw damage degree has been somewhat alleviated. The interaction between chemical corrosion and freeze-thaw cycles is mutually reinforcing, affecting the damage and deterioration of sandstone samples.