TY - JOUR
T1 - Integrating the four-probe method and SWCC device to measure electrical resistivity anisotropy of unsaturated soil
AU - Wu, Y.
AU - Wang, Y. H.
AU - Niu, Q.
N1 - Publisher Copyright:
Copyright © 2017 by ASTM International.
PY - 2017
Y1 - 2017
N2 - Electrical resistivity is often utilized to estimate different flow-related properties of unsaturated soils, such as hydraulic conductivity. To be better utilized for such a purpose, the electrical resistivity anisotropy has to be characterized to account for the anisotropic nature of soils. Thus, a testing cell equipped with two individual four-probe arrays was designed and manufactured using the 3D printing technique. The testing cell was integrated with a soil water characteristic curve (SWCC) device, and therefore both the soil resistivity anisotropy and SWCC could be measured simultaneously in the same sample. Numerical simulations using the finite element method (FEM) were carried out to characterize the measurement biases due to the boundary effect from the finite sample size and the influence of the electrode sizes, and then to determine the associated correction factors. The validity of the correction factors was also experimentally verified. Experimental results on the mica samples reveal that the electrical resistivity in the vertical and horizontal directions (i.e., ρV and ρH) increases as the suction increases or the degree of saturation decreases. In addition, the anisotropic factor, λ √ρV/ρH, was found to gradually increase with increasing suction or decreasing water content.
AB - Electrical resistivity is often utilized to estimate different flow-related properties of unsaturated soils, such as hydraulic conductivity. To be better utilized for such a purpose, the electrical resistivity anisotropy has to be characterized to account for the anisotropic nature of soils. Thus, a testing cell equipped with two individual four-probe arrays was designed and manufactured using the 3D printing technique. The testing cell was integrated with a soil water characteristic curve (SWCC) device, and therefore both the soil resistivity anisotropy and SWCC could be measured simultaneously in the same sample. Numerical simulations using the finite element method (FEM) were carried out to characterize the measurement biases due to the boundary effect from the finite sample size and the influence of the electrode sizes, and then to determine the associated correction factors. The validity of the correction factors was also experimentally verified. Experimental results on the mica samples reveal that the electrical resistivity in the vertical and horizontal directions (i.e., ρV and ρH) increases as the suction increases or the degree of saturation decreases. In addition, the anisotropic factor, λ √ρV/ρH, was found to gradually increase with increasing suction or decreasing water content.
KW - Boundary effect
KW - Effect of electrode size
KW - Mica
KW - Resistivity anisotropy
KW - Soil water characteristic curve (SWCC)
UR - http://www.scopus.com/inward/record.url?scp=85028377998&partnerID=8YFLogxK
U2 - 10.1520/GTJ20160160
DO - 10.1520/GTJ20160160
M3 - Article
AN - SCOPUS:85028377998
SN - 0149-6115
VL - 40
SP - 698
EP - 709
JO - Geotechnical Testing Journal
JF - Geotechnical Testing Journal
IS - 4
ER -