MONITORING WATER MIGRATION PROCESSES IN CRACKING CLAY SOIL WITH DEPTH PROFILES OF SQUARE ARRAY RESISTIVITY MEASUREMENTS

摘要

It has recently been shown that electrical resistivity measurements with the square array give valuable information about surface soil cracks (Samouelian et al., 2004), subsurface crack dynamics (Greve et al, 2010) and water migration processes within a profile of cracking soil (Greve et al., submitted). There are three independent arrangements of the current and potential electrodes within a square array, which have been termed α,β,γ arrays (Habberjam and Watkins, 1967) (Figure 1). The tripotential condition states that the resistances measured with the β and γ arrays sum to the resistance measured with the α array (R_β+R_γ=R_α), which leads to the definition of the tripotential error (E_(tp)) as E_(tp) = (R_α-(R_β+Rg))/R_α. In isotropic and homogenous ground R_γ = 0 and R_β = R_α. In heterogeneous ground, however, R_γ ≠ 0 and R_β ≠R_α.