Abstract: Both the soil property and the void ratio are important factors affecting the permeability coefficient of the fine-grained soils. The influence of the soil property is mainly reflected in the reduction of effective seepage diameter of the soil voids by the thickness of the bonded water film in the soil particles. To analyze the influence of the void ratio change on the permeability coefficient, this time, an improved seepage test device was used to perform the permeability test on the old clay, the alluvial-diluvial silty clay and the Dianchi Peat soil samples. The relationship between the permeability coefficient K and the void ratio change of these three typical soil samples was systematically analyzed. The test shows that, with the decrease of the void ratio, the permeability coefficient gradually decreases, showing a positive correlation, and a power function relationship, the relationship is, different soil types, the value of B is different. For old clays, the void ratio has little effect, but for silty clays, the special structure and material composition of peaty clays play a decisive role.

Key words: Improved Seepage Test Device, Seepage Testing, Void Ratio, Permeability Coefficient