Study on permeability characteristics of tailings sand considering particle features

The permeability of the grouting medium is a core parameter determining the grouting effect. To explore the grouting and cementation reinforcement technology for tailings dam faces and improve the toughness of tailings dams against overtopping floods, it is necessary to consider the complexity of the stress environment and particle characteristics of tailings particles and understand the relationship between tailings permeability characteristics and their particle characteristics. Based on tailings samples from the Wangjiazhuang tailings dam in Luoyang, Henan Province, a tailings particle characteristic database was constructed. Based on the improved fractal reconstruction method and the finite element method, a microscopic seepage model highly consistent with the actual tailings particle characteristics was established, and the seepage characteristics of fine-grained tailings under different particle characteristics were studied. The results showed that: (1) there were significant differences in particle size distribution and particle shape among sand, silt, and clay particles in the tailings. As the particle size decreased, the particle flatness increased from 1.37 to 2.96, and the convexity decreased from 0.107 to 0.023. The particle surface gradually became smoother and the shape became flatter. (2) As the tailings particle size decreased, the permeability coefficient decreased exponentially. The permeability coefficients of sand and silt differed by more than 20 times. The permeability coefficient of tailings particles was positively correlated with porosity and negatively correlated with flatness. Under the same confining pressure, the permeability coefficient of clay particles changed less. (3) The influence of tailings particle characteristics on permeability coefficient was achieved by changing the “width” and “torsion” of the seepage channel. The above results help improve the accuracy of predicting the permeability characteristics of fine-grained tailings and facilitate the determination of grouting parameters.