冻融循环对兰州黄土渗透性变化的影响

在季节冻土区, 周期性的冻结与融化持续改变着土体内部结构, 土的孔隙率与渗透性也随之产生相应的变化. 针对这一现象进行了原状黄土和重塑黄土的冻融循环试验和冻融循环后的渗透试验. 结果显示: 随着冻融循环作用的进行, 原状黄土与重塑黄土干密度的变化趋势都是先增大后减小, 然后趋于稳定. 由于渗透系数与干密度呈负线性关系, 所以随着冻融循环次数的增加, 原状黄土与重塑黄土的渗透系数都是先减小后增大, 最后在4×10^-4~6×10^-4 cm·s^-1之间趋于一个稳定值. 因为重塑黄土是扰动土, 土结构中的颗粒大小较为均匀, 而原状黄土的土结构中颗粒大小不均匀, 导致重塑黄土的渗透系数始终大于原状黄土.

Research on the Lanzhou loess's permeabilities changing with freezing-thawing cycles

In seasonally frozen soil regions, as the internal structures of soil changing periodically under freezing-thawing cycle, the porosity and permeability of the soil change inevitably. In this study, a series of freezing-thawing cycle experiments of original and remolded loesses were conducted, followed by infiltration experiments. The results of these experiments show that the original and remolded loess's dry densities increase frist, then decrease and finally reach a steady state with increasing freezing-thawing cycles. Because of the negative linear relationship between dry density and coefficient of permeability, the permeability coefficient decreases first and then increases after 10 freezing-thawing cycles, finally reaches a stable value of between 4×10^-4 and 6×10^-4 cm·s^-1. Because the remolded loess has been disturbed and the particles in structure are homogeneous while the original loess is not disturbed and the particles in structure are unhomogeneous, the permeability of remolded loess is always greater than that of original loess.