季节性冻融土壤的冻融特点和减渗特性的

本文基于季节性冻土地区冻融期间自然冻融土的大田入渗试验，分析了田间耕作土壤的冻融特点，讨论了冻融土壤的减渗特性；探讨了冻融土壤的减渗机理。研究结果表明：在不同的冻融阶段，土壤冻层的形态，厚度、层数和层位不同，对入渗水流的控制和影响不同；冻结土壤的减渗特性随冻融阶段的变化面变化；而结条件下，土壤导水率的减小是其入渗能力减小的根本原因，而土壤液态水的相变是土壤导水率减小的要源所在。研究结果对于季节性冻

EXPERIMENTAL STUDY ON THE FREEZING AND THAWING FEATURES AND REDUCTION INFILTRATION CHARACTERISTICS OF SEASONAL FREEZJNG AND THAWING SOILS

Based on the field infiltration experiments of natural freezing and thawing'soils within the freezing and thawing periods, in this paper the freezing and thawing features of cultivated soils are analysed, the basic characteristics of reduction infiltration of freezing and thawing soils are discussed, and the reduction infiltration mechanism of freezing and thawing soils is inquired into. The results indicated that at different freezing and thawing stages, the formation, thickness, number and position of frozen layers in soils are different and the frozen layers have different control and effect on infiltrating flow, that the characteristics of reduction infiltration varies with the freezing and thawing stages, and that under freezing and thawing conditions, reduction of soil water conductivity is the basic reason for reduction of soil infiltration ability and the phase change of liquid water in soil is the origin of the reduction of soil water conductivity. The results are of theoritical value to further study on the infiltration law of field freezing and thawing soils in the districts with seasonal freezing and thawing soils and are of practical value to determine technical parameters for saving-water irrigation within the winter and spring irrigation in these districts.