Estimation of soil porosity in mine tailing using parameters from instrumented oedometer test

In the geological field, unexpected tailing failures have recently occurred and caused critical damage. The objective of this study was to evaluate the porosity of mine tailing using compressibility and elastic wave velocities from an instrumented oedometer test. Three samples (MS1, MS2, MS3) were obtained from the mine tailing at different depths, and their properties were assessed. The oedometer test was conducted from 0 to 1280 kPa for MS1, MS2 (with various initial stresses), and MS3, and the elastic wave velocities were measured during each loading and unloading step. The specific gravity, X-ray fluorescence, and X-ray diffraction test results revealed a portion of hematite (Fe₂O₃) in all the samples. According to the instrumented oedometer test, the compressibility and elastic wave velocities of the samples varied with respect to the sampling depth and stress conditions. In particular, the α factor and β exponent from the shear wave velocity followed the empirical relationship of general soil types. Empirical porosity evaluation methods reliably estimated the sample porosity at shallow depths by using the parameters from the instrumented oedometer tests. Thus, the in situ porosity at a mine tailing can be effectively evaluated if the profiling of elastic velocities in the field is available.