Importance of Borehole Logging Studies in Design of Foundation for Civil Engineering Structures

Design of foundation, an important role for any major civil engineering structures viz. Nuclear and Thermal Power Plants, bridges, dams, barrages, etc., involves geotechnical investigations for determining detailed subsurface information; site characterization and damping characteristics of soil/ rock, etc. Borehole geophysical logging, compliment and supplement to geotechnical investigations, provide in-situ properties of subsurface lithology in a rapid, non-destructive and cost-effective way. Purpose of the paper is to highlight importance of borehole logging like nuclear, sonic and electrical logs in foundation studies for determining in-situ density, compressional wave velocities (Vp), shear wave velocities (Vs) and subsurface resistivity for identifying depth and quality of bed rock, different subsurface layers or strata, presence of liquefaction zone, Low Velocity Layer (LVL) and structural discrepancy, i.e. cracks, fracture and fault zone/shear zone, etc. and also calculating dynamic elastic properties of subsurface lithology, important for design-foundation of important civil structures. This paper is enlightened with different case studies where CW&PRS, Pune was deeply involved in design-foundation of important civil structures like Nuclear and Thermal Power Plants, jetties, etc. by providing subsurface geophysical and geotechnical information using land and underwater borehole logging. Discussion on importance of borehole geophysical logging in foundation studies in this paper may be useful to geotechnical engineers and professionals dealing with design-foundation of important civil structures.