In-situ Stress Characteristics and Tectonic Significance of the Hongnipo Copper Mine in the Sichuan-Yunnan Region

The geological setting in the Sichuan-Yunnan region is complicated, which leads to the special in-situ stress characteristics of underground mines in this region. This study aimed to elucidate the in-situ stress field within the Hongnipo copper mine and analyze its impact on underground mining. To this end, hydraulic fracturing tests were conducted in 3 boreholes, yielding in-situ stress data from 15 measuring points. The field test results showed a linear increase of in-situ stress with increasing of depth. Above the depth of 400 m, the in-situ stress in this area was characterized by horizontal stresses predominantly, and it was a stress field of reverse fault type (σ_H > σ_h > σ_v). The direction of maximum horizontal principal stress was oriented towards the northwest. The potential risk of rockburst associated with underground mining activities might occur at the depth of 578 m. Fault stability analysis revealed that underground mining was hardly affected by tectonic activities. It showed that the research of Hongnipo copper mine was consistent with the characteristics of Sichuan-Yunnan region. This research hold significant reference for underground mining in Hongnipo copper mine and surrounding areas.