The hydropower sector plays a crucial role in Nepal's national economy, especially given its mountainous terrain and abundant water resources. With the necessity to redirect high discharge for large-scale projects, constructing tunnels becomes imperative. Tunnels and caverns are identified as the most effective options to maximize the practical generation capacity of Nepalese hydro projects. Nepal is actively pursuing the construction of hydropower tunnels, with numerous domestic projects in the pipeline. However, it's essential not to overlook the challenges associated with tunnel construction, as they can lead to undesirable outcomes. Therefore, a comprehensive understanding of the factors causing such problems, their consequences, and subsequent remedial measures are indispensable for the successful development of tunnel projects in Nepal. The aim of this research is to identify the primary challenges and their impact encountered during the construction of the tunnel at Seti Khola HPP. This investigation took place from The aim of this research is to explore the major problems faced and their consequences along with their remedial measures during the construction of the tunnel at Seti Khola HPP. This investigation took place from January 2024 to February 2024. It involved direct field observations, interviews with representatives from the client and contractor, questionnaire surveys administered to employees of both parties and design and supervision consultant, as well as Key Informant interview (KII) with teams from the client, consultant and contractor. Additionally, secondary data were gathered from literature, journals, articles, and reports pertaining to Seti Khola HPP. Several significant issues were identified during the study, including inadequate underground investigation during the design phase, inadequate selection of competent contractors, insufficient availability of proper construction equipment, ineffective resource utilization, inadequate communication among the stakeholders, and delays in making timely decisions regarding work instructions from the clients. vii This study recommends conducting thorough geotechnical investigations and underground explorations utilizing the latest available technology during the project's planning phase. Proper alignment selection should precede geotechnical investigations, and contractors should be selected based on their competence and experience. Close monitoring and timely resolution of public-related issues are advised, with separate teams established by the client to address social and technical concerns. Contractor bills should be meticulously verified and paid promptly, and construction materials should be adequately stored to prevent work disruptions.

Keywords

Tunnel Construction, Geotechnical Investigation, Tunnel squeezing, monitoring, competent contractor, time and cost overrun.

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