Abstract
The resource utilization of iron tailings is of great significance for all countries in the world. Considering the particle composition and physicochemical characteristics of iron tailings, fiber and lime were used to modify iron tailings. The fiber content was 0%, 0.25%, 0.5%, 0.75%, and 1%, and the lime content was 0%, 2%, 4%, 8%, and 10%, respectively. Through a direct shear test, the shear stress displacement (τ-δ) curves and shear strength of modified iron tailings, under the action of a 0 freeze-thaw cycle and 1 freeze-thaw cycle, were tested. As statistics have shown that there are uncertainty factors associated with direct shear tests, the shear strength index cohesion c and internal friction angle φ of the modified iron tailings were analyzed using the Monte Carlo method. The results show that the τ-δ curve of the fiber-modified iron tailings is a hardening-type curve and that of the lime-modified iron tailings is a softening-type curve. In the direct shear tests, the main uncertain factors are the specimen diameter, vertical force, and horizontal force. The diameter of the sample obeys a normal distribution, and the vertical and horizontal forces obey a uniform distribution. The results of the Monte Carlo simulation show that both c and φ obey a normal distribution. Under a 95% confidence condition, the effect of fiber on the cohesion on iron tailings is obvious, but the effect on the internal friction angle is not obvious. However, the values of c and φ of the iron tailings are clearly improved by lime. Additionally, the iron tailings modified by a fiber content of 1% and those modified by a lime content of 8% have the best frost resistance.
Highlights
With the development and utilization of mineral resources, a large number of tailings have been produced
Us, in recent years, scholars have conducted a lot of research on the use of iron tailings as building materials. ey are mainly used in the preparation of cementitious materials [5], Portland cement clinker [6], concrete fine aggregate [7,8,9,10,11], concrete mineral admixture [12], mortar for laying and coating [13], road materials [14, 15], etc., and have achieved good results
Wang et al [16] studied the mechanical properties of tailing sand under the condition of dry and wet cycles. e results show that the water characteristic curve of tailing sand tends to move to the left with the increase of dry and wet cycles, which provides a basis for understanding the mechanical properties of tailing sand and the stability of tailing dams under the condition of dry and wet cycles
Summary
With the development and utilization of mineral resources, a large number of tailings have been produced. Erefore, according to the Mohr–Coulomb theory, a direct shear test can be used to study the shear mechanical index cohesion c and the internal friction angle φ of the modified iron tailings. Through a statistical analysis of the uncertainty factors associated with direct shear tests, the Monte Carlo algorithm is used to analyze the shear strength indexes c and φ of the modified iron tailings, so as to provide a basis for the resource utilization of tailings. Fiber and lime are used to modify iron tailings, and 0 freeze-thaw and 1 freeze-thaw direct shear tests are carried out. Erefore, the Monte Carlo algorithm is used to fit the uncertainty in the process of the direct shear test, and the statistical rules of c and f of the modified iron tailings are obtained. 12.3 31.9 22.3 15.6 22.1 41.5 76.7 92.9 36.4 37.0 14.0 32.3 32.3 54.7 48.8 51.6 87.4 77.7 φ ( ゚)
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