Development of a hydraulic conductivity apparatus for bentonite soils

Abstract

Measurement and interpretation of hydraulic conductivity in porous media is a complicated process, and many laboratory apparatuses exist for different soil types and conditions. To use models for interpretation and prediction of hydraulic conductivity, accurate test measurements are required. A new hydraulic conductivity apparatus is presented that includes simultaneous control of volume and stress states. The apparatus includes the ability to automatically control volume to apply selected displacement boundary conditions while imposing radial flow conditions. The capabilities of the system are displayed using two selected hydraulic conductivity tests on an unsaturated sand–bentonite mixture, which is a swelling soil. Hydraulic conductivity on the order of 10−13 m/s was measured using the new system and compared closely with previously measured values using a similar material. Post-test measurements displayed internal water content, density, and saturation changes that occurred during testing.