Numerical Study on the Fracturing Mechanism of the Belt Conveyor Roadway in Dagushan Open-Pit Mine and Control Measures Evaluation

Dagushan Iron Mine is a large-scale open-pit mine. In this mine, the belt conveyors residing in the rock slope are employed for ore haulage. However, after the − 210 m bench was excavated, many fractures occurred in one of the roadways placing the belt conveyors. In this paper, this engineering case was introduced in detail and the fracturing mechanism was investigated numerically. A numerical model containing complex stratigraphy and geological conditions was built for fracturing mechanism analysis. The strain-softening constitutive model was adopted to describe the post-failure behavior of rock mass. The model was validated with field monitoring data and spot observations, and then used to analyze the interactions between the roadway and rock slope induced by bench excavation. The deformation and stress evolutions in the rock slope and the fracturing process of concrete lining were further clarified for this roadway-landslide system. The numerical results show that the − 210 m bench excavation activated the F14 and F15 faults (with activity initiating low and extending upwards) and generated large shear bands, forming an isolated potential sliding strip. The large displacement of the potential sliding strip acting on the roadway led to the fracturing of the concrete lining. The rock masses around the roadway have also been damaged severely. The control measures of slope cutting were suggested for future production and evaluated using the numerical model. It was found that the suggested control measures could manage the convergent deformation of the roadway to within the appropriate limit and ensure that the belt conveyor can be used for ore haulage until nearly the end of production. The suggested control measures are feasible and practical, and provide a reference for addressing similar engineering problems. Highlights This paper reports an engineering case of the Dagushan open-pit mine in detail, which is about the fracturing of the concrete lining of the belt conveyor roadway induced by slope excavation. To investigate the fracturing mechanism, a numerical model containing complex stratigraphy and geological conditions was built and basically verified by the field monitoring data and spot observations. The numerical studies show that the -210m bench excavation activated faults from down to up to form an isolated possibly-sliding strip and the large displacement of the possibly-sliding strip acting on the roadway leading to the fracturing of the roadwa