As a kind of special soil

loess is widely distributed in seasonally frozen regions. The test samples are the undisturbed Q3 loess with obvious anisotropy from a building site in Xi’an city. The saturated hydraulic conductivity of undisturbed loess considering the influence of density is measured by triaxial permeability apparatus GDS. It can be obtained that the hydraulic conductivity in horizontal is higher than that in vertical. The saturated hydraulic conductivity decreases with the increase of density. However

the anisotropic permeability of undisturbed loess increases with the increase of density .The loess

which has the same density but a different initial moisture content

experiences freezing-thawing cycles in an closed system. The results show that the saturated hydraulic conductivity of the samples

which has experienced freezing-thawing cycles

increases with the initial moisture content increasing. However

the anisotropic permeability of loess experiencing freezing and thawing reduces with the initial moisture content increasing. The saturated hydraulic conductivity increases first

then reaches a steady state with increasing freezing-thawing cycles. However

the anisotropic permeability of undisturbed loess changes significantly with increasing freezing-thawing cycles. The ratio of loess permeability decreases significantly with the increase of freezing-thawing cycles. The test results indicate that the anisotropy of loess structure has a significant effect on the anisotropic permeability. Meanwhile

Freezing-thawing changes the permeability of loess by changing its microstructure.