Influence of Fracture Zone on Final Slope Displace-ment : Insights from Long-Term Monitoring in the Une Mine

Abstract

The final slope of Une mine experienced sudden increases in displacement in specific sections during the typhoons of 2007 and 2011, as observed through long-term monitoring since the excavation from the top. The rise in groundwater due to increased rainfall was identified as a significant factor leading to measures specifically targeting rainfall. Notably, despite previous instances of heavy rainfall, sudden displacements occurred without clear triggers, emphasizing the need for a comprehensive understanding of the behavior of the rock slope. Future maintenance efforts rely on elucidating these mechanisms, often solely attributed to rainfall. To analyze factors beyond rainfall affecting the final slope's displacement, this study introduces the concept of "unit rainfall displacement," representing displacement per unit rainfall. The unit rainfall displacement is defined as the annual final slope displacement divided by the cumulative effective annual rainfall. The cumulative effective annual rainfall is determined by cumulating rainfall for events with 100 mm or more rainfall for a year, based on previous studies indicating that the final slope exhibits behavior in such conditions. Focusing on the W4, a key fracture zone of Mt.Buko, this study explores the relationship between unit rainfall displacement and the exposure status of W4 on the final slope. ’ and the exposure status of W4 on the final slope. As a result, this study revealed an overview of W4's impact on the variations in unit rainfall displacement, providing insight into the rock slope displacement attributed to W4.

Keywords

• rock slope
• monitoring
• rainfall
• fracture zone
• excavation shape