Determination of the capillary permeability coefficient and its application to capillary rise on ionic rare earth

The Terzaghi model assumes that capillary rise permeability coefficient of soil is always saturated permeability coefficient, which brings about a great differences between the model results and actual measurements. In order to overcome the shortcomings, the key parameter of Terzaghi model was redefined with in-situ leaching of ionic rare earth mining as the engineering background, and the modified parameter was used to analyze the test results of capillary rise of ionic rare earth. The saturated permeability coefficient of Terzaghi model was replaced with the capillary permeability coefficient, and the latter had different values and meanings with the former. Four groups of capillary rise tests on ionic rare earth were carried out, their maximum grain sizes were 0.3mm, 0.6mm, 1.18mm and 4.75mm respectively, the feasibility of modified model was proved with fitting results of the experimental data. Putting measured saturated permeability coefficients of corresponding rare earth into Terzaghi model, the advancement of modified model was testified by comparing the estimated data of Terzaghi model and modified model with test data. The modified model was used to fit and analyze the test results of capillary rise experiment on ionic rare earth. Results show that the modified model is more consistent with reality than the original model, and the value of capillary permeability coefficient is closer to the actual value. Under water capillary rise in ionic rare earth, the values of capillary permeability coefficient decrease and the maximum height of capillary rise increase gradually with increasing the maximum particle size of soils. For the ionic rare earth of the same particle size, the value of capillary permeability coefficient is less than saturated permeability coefficient. Capillary rise velocity takes on a rapid decline at first, and then slowly decreasing trend over time.