Experimental Study on the Mechanical Properties of Saturated Tailing Sand with Different Particle Sizes

Abstract

The particle size distribution of tailing sand will affect its strength, deformation and mechanical properties, thus affecting the overall safety and stability of the tailing dam. The main purpose of this study is to obtain the gradation of sand samples with the best shear strength and seepage effect by studying the influence of particle size on the mechanical properties of saturated iron tailing sand. The tailings were sampled from Yangjiawan tailing reservoir of Chengchao Iron Mine, and the moisture content test, particle size distribution analysis and scanning electron microscope test (SEM) were carried out on the samples. It is measured that the average moisture content of the tailings is 12%, and the gradation is generally poor. SEM was used to observe the microstructure of the three kinds of particles, and it was found that these structures were more likely to be damaged under load, which was not conducive to the improvement of the strength of tailings. Through the consolidation undrained test of five particle size groups, it is concluded that the larger the particle size is, the greater the shear strength will be. The Cu indicates the width of the distribution range of the grading curve, the Cc indicates the distribution pattern of the grading curve, and they are both used to indicate the particle grading of sand. Then, by changing the sample gradation, the coefficient of uniformity (Cu) and the coefficient of curvature (Cc) of the gradation parameters are controlled to remain unchanged, respectively. By changing another parameter, it is found that there is a close relationship between the coefficient of uniformity and the coefficient of curvature and the shear strength through the triaxial shear action, three kinds of tailing sand gradation with better strengths are obtained. Based on the study of strength characteristics, the permeability coefficients of three kinds of tailing sands are calculated by using the seepage failure test. The test results show that when the coefficient of uniformity is 5.5 and the coefficient of curvature is 1, the permeability coefficient is 1.699 × 10−3 cm/s, and the shear strength and permeability of the sample are the best.