Infiltration mechanism of organosilicon hydrophobic material under a viscosity–temperature model and evolution of water barrier performance in subgrade soils

This study examined a waterproofing layer composed of organosilicon hydrophobic material to inhibit capillary water rise in subgrades. The infiltration behaviour of the hydrophobic solution and its impact on the evolution of water barrier performance were systematically investigated. A viscosity–temperature model was established to analyze infiltration depth, while permeation tests on layered soils revealed the permeability of the waterproofing layer. A water–seepage attenuation coefficient was introduced to quantify the layer’s water barrier performance and its evolution. Results indicate that infiltration depth is jointly controlled by solution viscosity, temperature, and initial soil moisture content. The permeation coefficient is primarily affected by the interaction between infiltration depth and the permeation coefficient of the layered soil. Under continuous seepage, the permeability remains essentially stable. Higher water–seepage attenuation coefficients correspond to stronger water barrier performance; they are constrained by initial moisture and increase with greater hydrophobic material amounts, eventually stabilising.