Hydraulic Conductivity Behaviors of Karst Aquifer With Conduit-Fissure Geomaterials

This study used laboratory analog and numerical experiments to simulate groundwater flow in karst aquifer and investigated the effect of dimension factors and water pressure on the hydraulic conductivity for karst groundwater flow in conduit-fissure medium. A coupled Darcy-Navier-Stokes mathematical model were developed to simulate groundwater flow transmitting process in karst aquifer. The Darcy's law was used to model the flow in the fissure and the Navier-Stokes equations were used for the flow in the conduit. A laboratory analog which simulate the conduit-fissure domains of a karst aquifer was used to provide verification of proposed mathematical models and the calibration of numerical simulations. Numerical simulations were adopted to solved the coupled Darcy-Navier-Stokes mathematical model. The numerical simulation results for flow matched well with laboratory experimental results. Furthermore, the hydraulic conductivity was identified as four control factors (conduit diameter, fracture aperture, initial hydralic pressure and strata dip angle) by the numerical simulations. A new empirical equation was proposed to derive the hydraulic conductivity. The contributions of each factor on the hydraulic conductivity were evaluated by variance analysis. The evidence shows that the conduit diameter and fracture aperture have the most influence on the hydraulic conductivity.