Abstract: Insitu permeability tests in the basalt residual soils were required in the Biwei Expressway in Guizhou. The doublering permeability method was selected for the basalt saprolite soils with different degrees of weathering. The test results demonstrate that the coefficient of permeability of the reddish brown residual soil is greater than that of yellowish brown soil. The colluvial soils with large degrees of weathering at both sides of the natural slope are slightly more permeable than soils with less degrees of weathering in the middle. The permeability decreases with the increase of the unit weight of the residual soils.

Key words: Basalt Residual Soil, DoubleRing Method, Permeability, Unit Weight