111-8 An Integrated Method Used for Findings of Geotechnical Site Characterization: A Case Study of Arun River Basin, Nepal

Session: Using Near Surface Geophysics to Investigate Geological Problems (Posters)

Poster Booth No.: 231

Presenting Author:

Gopal Bhandari

Authors:

Basnet, Krishna Bahadur¹, Shiwakoti, Indira², Bhandari, Gopal³

(1) Nepal Electricity Authority, Kathmandu, Nepal, (2) Nepal Electricity Authority, Kathmandu, Nepal, (3) Nepal Electricity Authority, Kathmandu, Nepal,

Abstract:

Geotechnical investigation is crucial to determine engineering properties of rock & soil. It is commonly carried out during foundation design & engineering construction. Arun valley lies in the northeastern part of Nepal which is also the deepest valley of the world. Arun River is one of the tributary of Koshi River where large hydropower are under construction. Upper Arun Hydropower Project is one of the mega hydro project that is going to be constructed in this river basin. Detailed geological & geotechnical study was carried out to implement this project. Geological mapping was conceded as initial stage to know the surface geology & rock type. In this project area, both direct & indirect method has been adopted for geotechnical investigation to know subsurface geology. Geophysical method like ERT, SRT, MASW etc. has been adopted as indirect method of investigation while drilling has been conducted to find out the strata, weak zone & bedrock. Televiewer test was carried out for conducting borehole scanning under dry condition collecting picture covering inclination, azimuth, aperture etc. of fractures zones with a fluid ingress above water level. Geologically the project area lies in lesser himalayan zone of sub-division of Nepal Himalaya. The major rock type found are Quartzite, amphibolite, marble, schistose gneiss, augen gneiss & banded gneiss. The main geological structure present is MCT.  Rock mass rating (RMR) & Q value was calculated & correlated each other to determine the rock mass quality.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9777

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