El Kamash, Walid, El Naggar, Hany, and Nagaratnam, Sivakugan (2021) Numerical analysis of lateral earth pressure coefficient in inclined mine stopes. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 7 (3). 61.

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Abstract

Investigating analytical solutions to determine stresses for mine stopes with inclined walls is essential for the design of stopes in the mining industry, contributing to the prevention of serious accidents. Two variables in the analytical formula used for computing the vertical stresses in mine stopes with inclined walls play a vital role in the design. The two variables are the coefficient of lateral earth pressure, Kα, and the ratio η. Here, Kα is the ratio of the normal earth pressure on the inclined wall at some level to the vertical stress at the same point and η is the ratio of the normal lateral earth pressure on the hanging wall to the normal lateral earth pressure on the footwall. The difficulty of using the analytical formula is to choose the correct values of both parameters. Hence, calibrating the formula involves selecting appropriate values of Kα and η in order to predict the actual results of the vertical stress, and consequently provide the designer with appropriate values that can be used in the design of mine stopes with inclined walls. Accordingly, in this study, the coefficient of lateral earth pressure in inclined mine stopes is numerically evaluated for various backfill friction angles; 30°, 35° and 40° with and without reference to the surrounding rock. The ratio η is also investigated at different depths ranging from 25 to 275 m. Moreover, Kα was formulated as a function of the ratio of the height to the breadth for different angles of the inclined stope, i.e., 60°, 70° and 80°. The considered cases in this analysis differ considerably from the commonly considered case in previous research, which completely overlooks the wall inclination effect. Furthermore, the considered cases better represent the actual in-situ conditions because they model the interaction between the sidewalls and the backfilling in the stope. The results have shown that the use of η = 0.6–0.8 and Kα ≤ Ka for the different angles of inclination in the analytical formula resulted in vertical stress being compatible with the numerical analysis results. Article highlights: Different researchers considered several aspects of mine stopes; however, none of them considered the effect of the stope wall inclination explicitly. Choosing appropriate values of the coefficient of lateral earth pressure, K, and the ratio of the normal lateral earth pressure on the hanging wall to the normal lateral pressure on the footwall, η, is crucial to predict the actual vertical stress. In this paper the ratio η is investigated at different depths ranging from 25 to 275 m. Moreover, K was formulated as a function of the ratio of the height to the breadth for different angles of the inclined stope.

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