滴水条件下层状土壤盐分积累特点研究

发布时间：2018-05-01 22:31

本文选题：滴水 + 层状土壤　；参考：《石河子大学》2015年硕士论文

【摘要】：为了探讨滴水条件下粘土夹层在层状土壤中的滞盐作用,本文针对不同构型的层状土壤进行土柱滴水入渗试验,并与均质土壤滴水入渗结果相比较。试验中,均质土壤为松沙土和轻壤土;层状土构型为松沙土夹轻粘土和轻壤土夹轻粘土;其中,均质土柱灌水量分别为1.0L、1.2L和1.5L;而层状土柱灌水量为2L。另外,层状土壤入渗试验中控制夹层厚度为5cm、10cm和15cm;控制夹层位置在30cm-40cm、35cm-45cm和40cm-50cm;以及双轻粘土夹层试验。从试验中得到了以下主要结论:(1)以渗透性较弱的粘土作为夹层的层状土,其对水分和盐分的运移都有阻滞作用,造成层状土滞盐,盐分含量相对增幅在脱盐区与积盐区之间存在突变,而且土层之间的渗透性差别越大,其阻滞作用越强。(2)粘土夹层对盐分运移的阻滞作用强于对水分运移的阻滞作用,使盐分大量的滞留在粘夹层中,而水分可以缓慢穿透夹层土壤下渗,进而使粘土夹层表现出拟半透膜现象,这种半透膜效应主要是由于在夹层土壤对于盐分的强吸纳作用下产生的。(3)随着粘土夹层厚度的增加,其对水分和盐分的运移的阻滞作用逐渐增强。当层状土壤由渗透性差别较大的松沙土和轻粘土组成时,15cm厚度夹层具有隔水蓄盐效果,不能表现出拟半透作用。10cm厚度夹层的拟半透膜效果比5cm厚度夹层的拟半透膜效果更明显。当层状土壤由渗透性差别不大的轻壤土和轻粘土组成时,10cm厚度夹层的拟半透膜效果最明显。(4)夹层层位越浅,其对水分的阻滞作用越强,盐分积累随着夹层层位的深度而增加,滞盐位置越深,返盐越困难。本文夹层层位在35-45cm时,盐分增加幅度最大,其次是40-50cm层位夹层,最后是30-40cm层位夹层。松沙土夹轻粘土构型土柱和轻壤土夹轻粘土构型土柱中,拟半透膜效应由强到弱,按夹层位置排序为35-45cm30-40cm40-50cm。(5)双粘土夹层构型土壤中的粘土夹层都对盐分有很好阻滞作用。将两个粘土夹层和它们中间的土壤层看作一个整体,并将其与不同层厚的单夹层构型土壤进行对比发现,当层状土壤由渗透性差别较大的松沙土和轻粘土组成时,其阻水作用等同于10cm厚度单夹层,大于5cm厚度单夹层,小于15cm厚度单夹层。双夹层的拟半透膜效果强于5cm厚度夹层的拟半透膜效果,小于10cm厚度单夹层的拟半透膜效果。当层状土壤由渗透性差别不大的轻壤土和轻粘土组成时,其阻水效果比三种厚度单轻粘土夹层都明显;且双夹层的拟半透膜效果比三种厚度的单夹层效果都明显。
[Abstract]:In order to study the salt retention effect of clay intercalation in layered soil under drip water, the soil column drip infiltration test was carried out for layered soils with different configurations, and the results were compared with those in homogeneous soil. In the experiment, the homogeneous soil is composed of loose sandy soil and light loam soil, and the layered soil is composed of loose sandy soil with light clay and light loam with light clay, in which the irrigation amount of homogeneous soil column is 1.0 L ~ (1.2) L and that of layered soil column is 2 L. In addition, the controlled interlayer thickness is 5 cm ~ 10 cm and 15 cm, the intercalation position is 30 cm ~ 40 cm ~ (-1) 35 cm ~ (-45) cm and 40 cm ~ (-50) cm, and the double light clay intercalation test. The following main conclusions are drawn from the experiment: (1) the layered soil with weak permeability as interlayer has a blocking effect on the migration of water and salt, resulting in the salt retention of layered soil. The relative increase of salt content has a sudden change between desalination area and salt accumulation area, and the greater the permeability difference between soil layers, the stronger the blocking effect of clay intercalation on salt migration is stronger than that on water migration. A large amount of salt is trapped in the clay interlayer, and the moisture can penetrate through the interlayer soil slowly, which makes the clay intercalation show the phenomenon of quasi-semi-permeable film. The effect of semi-permeable membrane is mainly due to the strong absorption of salt in intercalated soil. (3) with the increase of the thickness of clay intercalation, the inhibition of water and salt migration is gradually enhanced. When the layered soil is composed of loose sandy soil with different permeability and light clay, the intercalation with 15cm thickness has the effect of water insulation and salt storage, and the pseudo-semi-permeable effect of the layer with the thickness of 10 cm is more obvious than that of the interlayer with the thickness of 5cm. When the layered soil is composed of light loam with little permeability and light clay, the effect of pseudo-semi-permeable film is the most obvious when the thickness of intercalation is 10cm. The shallower the interlayer is, the stronger the inhibition of water is, and the salt accumulation increases with the depth of intercalation. The deeper the position of salt retention, the more difficult it is to return salt. In this paper, when the intercalation layer is in 35-45cm, the increase of salt is the largest, followed by 40-50cm layer intercalation and 30-40cm layer intercalation. The pseudo-semi-permeable membrane effect in loose sandy soil with light clay configuration column and light loam soil with light clay configuration column is from strong to weak, and the order of intercalation is 35-45 cm 30-40 cm 40-50 cm. 5) the clay intercalation in double-clay intercalation soil has a good effect on salt content. The two clay intercalations and the soil layer between them are considered as a whole, and compared with the single intercalation soil with different layers thickness, it is found that when the layered soil is composed of loose sand and light clay with different permeability, Its water blocking effect is equal to that of 10cm thickness single interlayer, larger than 5cm thickness single interlayer, and smaller than 15cm thickness single interlayer. The pseudo-semi-permeable effect of double interlayer is stronger than that of 5cm thickness interlayer, and is smaller than that of 10cm mono-layer. When the layered soil is composed of light loam and light clay with little difference in permeability, its water resistance effect is more obvious than that of three kinds of single light clay intercalation, and the pseudo-semi-permeable film effect of double intercalation is more obvious than that of three kinds of single interlayer thickness.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S275.6;S153

【参考文献】