Abstract: For rock slopes, the key to ecological slope protection technology is the formation of vegetation. In order to ensure plant
growth, soils should have good water-holding capacity and permeability. In this paper, the coupling relationship between permeability
and water retention capacity was studied by laboratory permeability experiment and evaporation experiment under different mixing
ratios of loess, diatomite and straw. The results show that the addition of diatomite and straw can effectively reduce the density of mixed
soil, which is beneficial to reduce the self-weight stress of the mixture and improve the stability of a slope. When diatomite and straw
are added separately, the permeability coefficient of the mixed soil increases exponentially. With the same amount of material,
diatomite is more effective in improving the permeability coefficient. When the diatomite and straw are mixed in a similar ratio, they do
not form mutual gains, but rise and fall. The addition of diatomite and straw can increase water retention capacity of the mixed soil, but
the effect of using diatomite is better than that of using straw. Adding diatomite and straw can prolong the steady evaporation stage of
soil and greatly improve the drought resistance of loess.

Key words: rock slope, ecological protection, diatomite, straw, permeability, water-holding capacity