(Special session/Open call for public) YARO15: Research activities on rock engineering during the COVID-19 pandemic

[3K0109-13-01] [Student presentation:Master's Course] Impact of fault and weak rock formation on mining-induced deformation of rock slope in open-cut quarry

○Cheng Zhang¹, Amagu Amagu clement¹, Jun-ichi Kodama¹, Atsushi Sainoki², Satoshi Ogawa³, Chika Umeda³, Yoshiaki Fujii¹, Daisuke Fukuda¹ (1. The University of Hokkaido, 2. Kumamoto university, 3. Ryoko Lime Industry Co., Ltd.)

Chairman:Akira SATO (Kumamoto University)

Keywords:limestone quarry, rock slope, stability assessment, distinct element method, fault

This study takes an open-cut limestone quarry in Japan as an example to discuss the mechanical interaction between two specific geological structures. In this quarry, below the mining area is a vertical fault intersecting with a weak rock formation almost parallel to the slope surface. Based on the unique geological structures, numerical simulations are conducted using discrete element method to elucidate the impact of two geological structures. The analysis results show that the vertical fault and weak rock formation significantly impact the rock slope deformation in mining progression. In the cases of an excavation-only model without geological structure, the slope surface deforms backward direction. However, in the fault and weak rock formation model, as the mining face crosses the fault, apparent forward slip occurs along with the weak rock formation. In this model, although the vertical fault constrains the sliding of the upper discontinuities at the early stage, the normal stress of the weak rock formation decreases gradually as the mining progresses, and local shear failure occurs at the intersection of the weak rock formation and fault, which leads to the slip. Furthermore, rock slope displacement due to the slip gradually decreases and eventually stabilizes as the working face gets away from the vertical fault, which means the slope eventually stabilizes. This study provides new insight into the deformation mechanism of the rock slope and serves as a reference for future mining and slope prevention work.