Influence and mechanism of upper unloading impact on the pressure distribution of the sidewall in the storage section of the orepass

To study the influence of unloading impact from the upper part of the orepass on the sidewall damage in the storage section, a discrete element model of particle flow in the storage section under the condition that the center of the ore-drawing port and the center of the orepass coincided was constructed by taking the ore storage section in the orepass of Shunfeng Iron Mine as a case study. The influence of unloading impact on the pressure distribute on the sidewall of the storage section at different unloading heights and the structural changes of the force chain inside the ore-rock bulk were studied in this paper. The results showed that: ①the influence of the unloading impact from the upper part of the orepass on sidewall pressure was mainly concentrated in the range of 14 m below the storage surface in the storage section of the orepass so that the variation of lateral pressure on the sidewall was positively correlated with the height of rock fall; ②under the impact of different unloading heights, the evolution of the lateral force chain caused the changes of the lateral pressure of the orepass, while the evolution of the longitudinal force chain led to the impact and compaction effect on the storage material in the orepass; ③the lateral pressure value of the sidewall under the same plane within the storage material had non-homogeneous characteristics, and its difference was closely related to the impact location of the ore-rock block, the energy carried by the impacted one and the void ratio of the storage material bulk in the orepass. The research results can help mines establish a reasonable matching relationship between the storage height of the ore storage section and the unloading height, which is beneficial to prevent the blockage of the ore storage section and reduce the wear of the orepass wall.