Enhancing Tunnel Construction Efficiency in Nepal: Challenges and Over-Break Mitigation in Drill-and-Blast Tunneling

Nepal, nestled amidst the Himalayas and bordered by China and India, faces substantial challenges in economic development due to rapid urbanization and population growth. Its diverse topography, ranging from low-lying plains to towering peaks, necessitates infrastructural development to utilize its major economic resources, including water, agriculture, and tourism. Tunnels are crucial for harnessing these resources, yet Nepal's reliance on traditional drill-and-blast methods has hindered progress due to limited expertise and financial constraints. This study explores the main challenges associated with drill-and-blast tunneling in Nepal, focusing on factors influencing over-break phenomena. Through a comprehensive analysis of existing literature and primary data from selected hydro-power projects, the research identifies key challenges such as management issues, tunnel geology, and construction equipment limitations. Additionally, it examines factors contributing to over-break, including powder factor, blasting pattern, and geological conditions. The study emphasizes the need for optimized management, local procurement of construction materials, and diversification of explosive suppliers to enhance efficiency and resilience in tunnel construction projects. Ultimately, this research provides valuable insights to optimize tunnel construction methodologies and address challenges, thereby promoting sustainable infrastructure development in the region.