Determination of Permeability Coefficient for Compacted Saturated Cohesive Soils in Underground Dams Using Physical Parameters

Estimation of hydraulic conductivity is a basic requirement in the design and implementation of underground dams. Evaluation of the materials used in the body of the underground dam in accordance with the standards and principles of design is essential. The question is whether experimental study of the materials used in the core of underground dams considering hydraulic conductivity parameters can produce an appropriate and easy model for estimation of saturated hydraulic conductivity. A new method was developed to prepare nine cohesive soil samples from a physical model of square cross-sections of three Plexiglass boxes having dimensions of 20 × 20 × 30 cm and a total height of 90 cm were used. The water level could increase toa head of 2 m on the model. The data was recorded at the 0.5, 1, and 1.5 m water heads. Stepwise regression was used to obtain data and present an equation for the saturated hydraulic conductivity coefficient. Two relationships for hydraulic conductivity of compacted soils were developed from the data. The secondary porosity was calculated according to Chapuis theory and nonlinear regression using ksat as a function of the secondary porosity exponent was introduced. The ksat curve and Srcwere drawn in linear formin a graph where axis x = w (soil moisture) and axix y = ρw/ρd.The charts demonstrate that Src and ksatare dense sticky with appropriate estimates to obtain lift.