Permeability coefficient of waterproof curtain by borehole packer test

Abstract

Borehole packer testing is a commonly used method to obtain the in-situ permeability coefficients, which are closer to the actual subsurface conditions compared to indoor tests. Current methods for determining permeability coefficients through borehole packer testing are limited to semi-infinite spaces like rock masses, failing to accurately describe the permeability coefficient of domains with different shapes, such as waterproof curtains, thus leading to evaluation errors. This study proposed a novel approach that utilizes borehole packer tests on waterproof curtains for determination of in-situ permeability coefficients. Based on the assumption that seepage within the waterproof curtain obeys Darcy's law, and following the borehole packer testing procedures, the method derives specific formulas for different cross-sectional shapes of waterproof curtain, experimental parameters and groundwater levels. Applying this method to calculate domains with actual shapes has higher permeability coefficient values compared to the previous semi-infinite domain methods, which had underestimated the permeability coefficients of waterproof curtains. The study presents a calculation model for borehole packer tests on waterproof curtains under various geological formations and conditions, providing a more accurate approach to determine the in-situ permeability coefficients.