Effect of geometric parameters of a restraining embankment on the stabilization of a deep open-pit mine excavation

Effective slope stabilization measure in deep open-pit mines not only ensures the safety of employees and equipment, but also makes sound economic sense. Based on field investigations of a landslide at the Lishan Iron Mine, south China, an innovative and effective method for slope remediation is proposed. An in situ foundation embankment was first created by excavating an anti-slip foundation trench, then the slope was stabilized by building a restraining embankment against the slope. The in situ foundation embankment had a dense structure which provided good resistance both to slip and to overturn. The restraining embankment was constructed out of mining waste rock and reduced the potential for slope failure by diminishing the potential free area of the slope and inhibiting the development of fractures in the rock mass forming the slope. In view of the structural characteristics of the in situ foundation embankment, an analytical solution for the safety factor of the embankment slope is deduced using theoretical analysis and numerical simulation for various combinations of geometric parameters. The results show that the safety factor of the embankment decreases with an increase of step height and step slope angle and increases with an increase of platform width and that step slope angle is the key parameter which affects the safety factor and both the maximum displacement and maximum plastic strain. The reliability of the proposed method is validated using field monitoring results from the Lishan Iron Mine after the embankment construction. This mine has now been safely running without landslides for two hydrological years after the stabilization works were constructed.