Lugeon test: new insights into calculated hydraulic conductivity

Abstract

While the Lugeon test was initially designed to aid in determining the grouting needs of dam foundations in fractured rock, its outcomes have been utilized by geotechnical engineers and hydrogeologists to estimate the hydraulic conductivity. Most of the practitioners use the long-established relation of 1 Lu ≈ 1 × 10 −7 m s −1 to calculate the hydraulic conductivity based on the determined Lugeon value. However, this relationship does not cover all the potential boundary conditions encountered in field conditions where the Lugeon test is applied, and the consequences on the estimated hydraulic conductivity are poorly understood. This paper aims to address this issue by revisiting existing mathematical formulations to calculate the hydraulic conductivity from the Lugeon test under the various boundary conditions. The paper also examines how the flow conditions and length of test intervals impact the recorded Lu and hydraulic conductivity values. It was found that the long-stablished relationship of 1 Lu ≈ 1 × 10 −7 m s −1 and the equation presented in the commonly used reference of the Code of Practice for Site Investigation (BS 5930:1999 + A2:2010) only present one of the potential boundary conditions for the Lugeon test.