Effect of repeated infiltration on permeability characteristics of remolded loess
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摘要: 甘肃黑方台黄土经历长期的灌溉入渗破坏了其原生结构,改变了不同深度黄土的颗粒级配,影响了土体的力学性质。为研究反复灌溉入渗对坡体的影响,通过室内土柱渗透试验研究了反复入渗对甘肃黑方台黄土渗透特性的影响,并研究了渗透作用下黄土中细颗粒运移的规律与模式。研究表明:①水力梯度对渗透速率影响较小而干密度对渗透速率影响较大;随着入渗次数的增加,重塑黄土的渗透性能变弱;②黄土在渗流力的作用下,存在细颗粒沿渗流方向运移的现象,且细颗粒在土柱中上部聚集最多;③影响细颗粒运移的因素有:水力梯度、干密度和渗透次数;其中细颗粒的运移量与水力梯度、渗透次数呈正相关,与干密度呈负相关,且水力梯度是影响细颗粒运移的主要因素;④在渗透过程中,细颗粒运移堆积,最终填充土体内孔隙,导致黄土的渗透性下降。Abstract: Long-term irrigation infiltration in Heifangtai, Gansu Province, destroys the original structure of loess, changes the particle gradation of loess at different depths, and affects the properties of the soil. In order to study the effect of repeated irrigation infiltration on slope, this paper studies the influence of repeated infiltration on the permeability of loess in Heifangtai, by indoor soil column penetration test, and the regularity and mode of fine particle migration in loess under osmosis. The following conclusions are reaches: ①The hydraulic gradient has little effect on the permeation rate and the dry density has a greater influence on the percolation rate. With the increase of the infiltration times, the permeability of the remolded loess becomes weaker. ②Under the action of seepage force, the loess shows the phenomenon of fine particles moving along the seepage direction, and the fine particles gather most in the upper part of the soil column. ③The factors affecting the migration of fine particles are: hydraulic gradient, dry density and penetration times; and the migration of fine particles is positively correlated with hydraulic gradient and penetration number, negatively correlated with dry density. The hydraulic gradient is the main factor affecting the migration of fine particles. ④During the infiltration process, the fine particles are continuously transported, and finally the pores in the soil are filled, and so the permeability of the loess is lowered.
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Key words:
- loess /
- repeated infiltration /
- permeability characteristics /
- fine particle migration
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表 1 试验参数
Table 1. Test parameters
条件 水头/cm 干密度/(g·cm-3) 渗透次数/次 不同水头 7 10 1.42 7 13 不同干密度 1.42 7 1.45 7 1.50 不同渗透次数 7 1.42 7 21 表 2 不同干密度对应的填土质量
Table 2. Filling quality corresponding to different dry densities
干密度ρ/ (g·cm-3) 体积V/cm3 含水率ω /% 公式 质量M/g 1.42 452.39 1.57 M=V·ρ· (1 +ω) 3 262.39 1.45 3 331.32 1.50 3 446.19 -
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