Assessment of Factors Influencing Over-break in Tunnel
Construction using Drill and Blast Method for Excavation
in Selected Hydro-power Projects of Nepal
Student: Shyam Sundar Bajgain
Supervisor: Er. Kumar Bajracharya
Submitted Date:
February, 2024
Abstract
Nepal, situated amidst the Himalayas and bordered by China and India, faces significant
challenges in economic development due to rapid urbanization and population growth.
With its diverse topography, ranging from low-lying plains to towering peaks, the
country's major economic resources, including water, agriculture, and tourism, necessitates
infrastructural development. Tunnels play a crucial role in harnessing these resources, yet
Nepal has historically relied on traditional drill-and-blast methods, hindering progress due
to limited expertise and financial constraints.
This study examines the major 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 collection from selected hydro-power
projects, the research identifies key challenges such as army management, tunnel geology,
and construction equipment limitations. Moreover, it investigates factors contributing to
over-break, including powder factor, blasting pattern, and geological conditions.
The study highlights the need for optimized army management, local procurement of
construction materials, and diversification of explosive suppliers to enhance efficiency and
resilience in tunnel construction projects. Additionally, recommendations include
comprehensive geological studies, ongoing stress condition monitoring, and the integration
of technology for over-break control. Collaboration and knowledge sharing among
stakeholders are essential for implementing these recommendations and improving the
effectiveness of tunnel construction practices in Nepal. Ultimately, this research
contributes valuable insights to optimize tunnel construction methodologies and mitigate
challenges, thereby fostering sustainable infrastructure development in the region.
Keywords
Harnessing, Diversification, Relied, Fostering, Phenomena, Insight