The Water Retention Curve (WRC) is a key tool used to characterize the behavior of partially saturated media, as it describes the variation of moisture content or saturation as a function of suction.
In general, in Chile, the most used instrument to measure the suction curve in commercial laboratories are pressure plate devices, which use the axis translation technique. Granular soils (such as sands and gravels), common in mining, tend to present air entry values (ψAEV) lower than 20 kPa.
This value presents a challenge for the regular pressure plate device as one of its fundamental assumptions, the continuous gas phase, is often not met for these low suctions (high degree of saturation). In spent ore materials, commonly classified as clayey gravels soils (GC), this problem is quite common and complicates the determination of the ψAEV which is typically in the mentioned range.
To assess the impact of not having data at low suctions, three curves obtained from parameterizations of different authors are analyzed, based on points measured with pressure plate devices (suctions greater than 10 kPa). These are implemented in two-dimensional finite element models to simulate a generic leaching heap irrigation case and review the impact of moisture within the mentioned suction range, based on the variation in the results.
