pH值对湿陷性黄土物理力学性能及微观结构的影响

Effect of pH on Physical and Mechanical Properties and Microstructure of Collapsible Loess

酸碱污染严重影响岩土工程长期稳定性。利用无侧限抗压强度、湿陷性试验、抗剪强度试验,研究不同pH值对黄土物理力学性能的影响,并采用XRD、SEM进一步探究不同pH值对黄土的影响机理。试验结果表明,与对照组相比(pH=7),pH值降低导致矿物成分衍射峰强度明显下降,且pH=3与pH=5中孔与大孔分别占比93.3%、89.9%,进而使无侧限抗压强度、湿陷性、抗剪强度下降。随pH值增加,在碱性环境中会生成大量胶凝物质,矿物成分衍射峰强度提高,与pH=7相比,p H=9与pH=11微孔与小孔分别增加25.0%、59.96%,使黄土物理力学性能得到提升。酸污染会降低黄土物理力学性能,而碱污染可提高黄土物理力学性能,可为黄土地区酸碱污染防治提供参考依据。

Acid-base pollution seriously affects the long-term stability of geotechnical engineering.Unconfined compressive strength,collapsibility test,and shear strength test were used to study the effect of different pH values on the physical and mechanical properties of loess.XRD and SEM were used to further explore the mechanism of the effect of different pH values on loess.The test results showed that compared with the control group(pH=7),the decrease in pH led to a significant decrease in the intensity of the diffraction peaks of the mineral components,and the proportion of medium and large pores in pH=3 and pH=5 was 93.3%and 89.9%respectively,which in turn led to a decrease in the unconfined compressive strength,collapsibility,and shear strength.With the increase of pH,a large amount of gelling material is generated in the alkaline environment and the intensity of the diffraction peak of mineral composition increases.Compared with pH=7,the micropores and small pores of pH=9 and pH=11 increase by 25.0%and 59.96%respectively,which improves the physical and mechanical properties of the loess.Acid pollution will reduce the physical and mechanical properties of loess,but alkali pollution can improve the physical and mechanical properties of loess,which can provide a reference basis for the prevention and control of acid and alkali pollution in loess areas.