Kathmandu Valley, the capital region of Nepal, is a heavily populated, rapidly growing and haphazardly urbanized metropolis of the country, primarily seated upon lacustrine and fluvial origin deposits. The valley is situated in an earthquake-prone zone with a long history of catastrophic earthquakes, so the valley deposit is vulnerable to intense ground shaking and wide-area liquefaction during mid to major earthquakes. Although a few localized geotechnical studies have been conducted in the valley, holistic understanding, modelling, and geotechnical soil characterization are not well documented. In this study, based on the geotechnical properties of a large number of borehole materials, we put efforts in characterizing the Kathmandu Valley soil, 3D modelling of subsurface lithology and stratigraphy, mapping the geotechnical properties, and finally shedding light on the geotechnical characteristics of the valley subsoils. For this, we collected and analysed more than 400 borehole-based geotechnical investigation reports, and also specifically investigated 10 new test borehole locations and measured the standard penetration test (SPT-N) values along with the required laboratory tests. The methods for geotechnical characterization and result interpretation include Rockworks 3D model of lithology and stratigraphy and graphical and statistical presentation of the index properties (i.e. grain size distribution, dry unit weight, plasticity parameters, natural moisture content, Atterberg limits, etc.), consolidation parameters, shear strength, SPT-N value, and shear wave velocity. We basically focus on highlighting the statistical and spatial variations of the above soil properties with the depth. Moreover, a few correlations of the geotechnical properties are also established. We expect the findings of this study will aid structural and foundation engineers in studying foundations, cost estimation of geotechnical investigations, and planning and implementing various civil engineering projects.

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