冻融作用下土壤粒径对浅埋潜水与土壤水转化的影响

Effects of Soil Particle Size on Transformation Between Shallow Phreatic Water and Soil Water Under Freeze-thaw Action

为了揭示土壤粒径对冻融过程中浅埋潜水与土壤水转化的影响,通过室内试验装置进行了-10、-20和-25℃依次降温恒温冻结62 d和自然消融13 d的冻融试验,研究了土壤粒径为0.1~0.5 mm(A土柱)、0.5~1.0 mm(B土柱)、1.0~1.5 mm(C土柱)、1.5~2.0 mm(D土柱)和2.0~2.5 mm(E土柱)的均质土柱在0.5 m地下水位埋深下的潜水蒸发量及潜水回补量变化特征。结果表明:冻结0~5 d时,土壤粒径越大,潜水蒸发速率越快,A、B、C、D和E土柱潜水蒸发速率分别为0.15、0.20、0.24、0.29和0.34 mm/d;冻结过程中累积潜水蒸发量随土壤粒径增大呈指数型递减,随着冻结气温的降低,土壤粒径对潜水蒸发量的影响减弱。消融0~5 d,粒径越大,土壤水对潜水的回补速率越快;随着消融时间增加,累积潜水回补量随土壤粒径增大而减小。研究成果对于土壤盐渍化防治和水资源科学评价具有重要的指导意义。

In order to reveal the effect of soil particle size on the transformation between shallow phreatic water and soil water during the freeze-thaw process,the freeze-thawing experiments of constant freezing temperature at-10,-20 and-25℃successively for 62 days and natural thawing for 13 days were carried out in the laboratory,and the variation characteristics of phreatic water evaporation and recharge in homogeneous soil column with soil particle size of 0.1~0.5 mm(A),0.5~1.0 mm(B),1.0~1.5 mm(C),1.5~2.0 mm(D)and 2.0~2.5 mm(E)under groundwater table depth of 0.5 m were analyzed.The results showed that the evaporation rate of phreatic water increased with the increase of soil particle size from 0 to 5 days under freezing,and the evaporation rate of phreatic water in soil column A,B,C,D,E was 0.15,0.20,0.24,0.29,0.34 mm/d,respectively.The accumulated phreatic water evaporation decreased exponentially with the increase of soil particle size during the freezing process,and the influence of soil particle size on phreatic water evaporation decreased with the decrease of freezing temperature.The recharge rate of soil water to phreatic water increased with the increase of soil particle size from 0 to 5 days under thawing.With the increasing of thawing time,the accumulated recharge of soil water to phreatic water decreased with the increase of soil particle size.The research results are significant for prevention of soil salinization and scientific evaluation of groundwater resources.