冻融循环对原状黄土抗剪强度的影响及微观解释

Effect of Freezing-thawing Cycle on Shear Strength of Undisturbed Unsaturated Loess and Its Microscopic Interpretation

为研究冻融循环对黄土边坡的影响,以甘肃省通渭县某地区原状黄土为例,采用三轴剪切试验研究了冻融循环作用对土体抗剪强度的影响,并通过核磁试验与扫描电镜试验解释其微观变化规律,分析了不同饱和度及冻融循环次数对原状黄土抗剪强度的影响。试验结果表明,原状黄土应力应变曲线与冻融循环次数和饱和度有关;粘聚力与内摩擦角随冻融循环次数呈现不同的规律;冻融循环次数影响原状黄土的土体孔隙结构。试验将NMR与SEM相结合,从微观层面更好地解释冻融循环对土体抗剪强度的影响。

In order to study the effect of freezing thawing cycles on loess slope,taking undisturbed loess in Tongwei County,Gansu Province as the research object,the impact of freezing-thawing cycles on shear strength of soil was studied by triaxial shear test,and its microscopic interpretation was conducted by nuclear magnetic test and scanning electron microscope test.The shear strength of undisturbed loess was studied by using different saturation and freeze-thaw cycles.The experimental results show that the stress-strain curve of intact loess is related to the number of freeze-thaw cycles and saturation.Cohesion and internal friction angle show different laws with the number of freeze-thaw cycles.The number of freezing-thawing cycles affects the soil pore structure of undisturbed loess.NMR and SEM were combined to better explain the effect of freezing-thawing cycles on shear strength of soil from the microscopic level.