Site-Specific Seismic Hazard Analysis for Shallow Tunnel in Nepal

Abstract

Abstract Several seismic codes are implemented for the design and construction of superstructures in Nepal but there is no seismic guideline for shallow tunnels which are often constructed using conventional engineering approaches. The uniform hazard spectrum was obtained after performing a Probabilistic Seismic Hazard Analysis at Dhulikhel and the target spectrum was estimated by comparing it with the spectrum recommended by the seismic code of Nepal Building Code NBC 105:2020 and Indian standard IS 1893:2016. The average response spectrum from ten recorded earthquake ground motions was selected from a peer ground motion database with the known shear wave velocity obtained from geophysical survey. The comparative analysis revealed that the design spectra for identical soil classes, as determined by this study are slightly higher than those prescribed by the present seismic code provisions. This finding emphasizes the necessity for developing more specific guidelines tailored to the design of shallow tunnels in Nepal to ensure their structural resilience in the event of an earthquake.