Abhishek Kumar , Anbazhagan, P. and Sitharam, T.G. (2013), Seismic Site Classification and Empirical Correlation between Standard Penetration Test N value and Shear wave velocity for Deep Soil Sites in Indo-Gangetic Basin,Pure and Applied Geophysics, Vol. 170(3), pp 299-318.

(a) Correlation between N-SPT and Vs values for all soil type for Lucknow; (b) Typical subsoil cross-section in Lucknow based on Jal Nigam reports; (c) Average 30 m shear wave velocity and N-SPT values as per NEHRP site classification for Lucknow (Ref: Anbazhagan et al., 2013)
(a) Correlation between N-SPT and Vs values for all soil type for Lucknow; (b) Typical subsoil cross-section in Lucknow based on Jal Nigam reports; (c) Average 30 m shear wave velocity and N-SPT values as per NEHRP site classification for Lucknow (Ref: Anbazhagan et al., 2013)

Subsurface lithology and seismic site classification of Lucknow urban center located in the central part of the Indo- Gangetic Basin (IGB) are presented based on detailed shallow subsurface investigations and borehole analysis. These are done by carrying out 47 seismic surface wave tests using multichannel analysis of surface waves (MASW) and 23 boreholes drilled up to 30 m with standard penetration test (SPT) N values. Subsurface lithology profiles drawn from the drilled boreholes show low- to medium-compressibility clay and silty to poorly graded sand available till depth of 30 m. In addition, deeper boreholes (depth =150 m) were collected from the Lucknow Jal Nigam (Water Corporation), Government of Uttar Pradesh to understand deeper subsoil stratification. Deeper boreholes in this paper refer to those with depth over 150 m. These reports show the presence of clay mix with sand and Kankar at some locations till a depth of 150 m, followed by layers of sand, clay, and Kankar up to 400 m. Based on the available details, shallow and deeper cross-sections through Lucknow are presented. Shear wave velocity (SWV) and N-SPT values were measured for the study area using MASW and SPT testing. Measured SWV and N-SPT values for the same locations were found to be comparable. These values were used to estimate 30 m average values of N-SPT (N30) and SWV (Vs30) for seismic site classification of the study area as per the National Earthquake Hazards Reduction Program (NEHRP) soil classification system. Based on the NEHRP classification, the entire study area is classified into site class C and D based on Vs 30 and site class D and E based on N30. The issue of larger amplification during future seismic events is highlighted for a major part of the study area which comes under site class D and E. Also, the mismatch of site classes based on N30 and Vs30 raises the question of the suitability of the NEHRP classification system for the study region. Further, 17 sets of SPT and SWV data are used to develop a correlation between N-SPT and SWV. This represents a first attempt of seismic site classification and correlation between N-SPT and SWV in the Indo-Gangetic Basin.

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