Study on Infiltration Characteristics and Micro-mechanism of Unsaturated Loess under Dry and Wet Paths
The unsaturated infiltration test of loess was carried out by using the transient cross-section method based on nuclear magnetic resonance(NMR)technology,and the infiltration characteristics of loess under two different paths of dry and wet were studied,and the infiltration mechanism of unsaturated loess under the paths of dry and wet was explored at the microscopic level by analyzing the changes in the distribution of pore water in the process of seepage.The results show that:in the process of moisture absorption and dehumidification,there is a big difference in the change rule of the permeability characteristics of loess,and there is a certain hysteresis in the relationship curve between the unsaturated permeability coefficient and the volumetric water content,and the unsaturated permeability coefficient is larger than that of the dehumidification path under the moisture absorption path when the degree of saturation is higher.In the whole seepage process,there is a certain primary and secondary relationship between the migration of water within the pore space,in the hygroscopic stage,the water is prioritized to fill the pore space with smaller pore size,while in the dehumidification stage,the pore space with larger pore size is prioritized to drain.The distribution of pore water is an important factor affecting the unsaturated infiltration of loess,and the influence of water stored in larger pores on the infiltration coefficient is dominant,while the influence of water stored in smaller pores to the infiltration of soil samples is relatively small.
loessnuclear magnetic resonanceunsaturated permeabilitywet and dry pathsmicromechanisms
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