5 Geotechnical Investigation and Its Applications in Seismic Design of Structures Srijit Bandyopadhyay, M. K. Pradhan, Raj Banerjee, V. S. Phanikanth, and S. J. Patil Symbols Dr 0 Change in effective overburden pressure r 0 0 Effective overburden pressure R r Recovery Ratio L a Actual length of sample in tube L t Total length of sampling tube driven below the bottom of borehole D S Inside diameter of sampling tube D C Inside diameter of cutting edge N Observed at field SPT value N 60 SPT (N) value corrected for 60% energy ef ficiency η H Hammer energy transfer ef ficiency (%) η B Bore hole diameter correction η S Sampler correction η R Rod length correction A c Cross-sectional area of cone Q c Tip load A f Surface area of friction sleeve c u Undrained shear strength q c Cone penetration resistance N k Cone factor D p Diameter of probe at deflate condition D h Diameter of the hole R c Radius of the measuring cell at the deflated condition which is at starting of the test r 0 Radius corresponding to point A r f Radius corresponding to point B B z Mass ratio m Mass of concrete block q Density of concrete block n Damping coef ficient of soil f 2 , f 1 Two frequencies at which the amplitude is equal to X m = ffiffi 2 p X m Maximum amplitude ; Angle of internal friction c Unit weight of soil above water table c sub Submerged unit weight of soil G Specific gravity of soil particles e Void ratio i c Critical hydraulic gradient 5.1 Introduction Soil is a natural aggregate of mineral grains, with or without organic constituents which is formed by disintegrating of rock through gentle mechanical means such as wind, erosion due to precipitation. The process of weathering of the rock in S. Bandyopadhyay (&)  M. K. Pradhan  R. Banerjee  V. S. Phanikanth Bhabha Atomic Research Centre, Mumbai, India e-mail: srijit@barc.gov.in M. K. Pradhan e-mail: mpradhan@barc.gov.in R. Banerjee e-mail: rbanerjee@barc.gov.in V. S. Phanikanth e-mail: phani@barc.gov.in S. J. Patil Heavy Water Board, Mumbai, India e-mail: sjp_patil@yahoo.co.in © Springer Nature Singapore Pte Ltd. 2019 G. R. Reddy et al., Textbook of Seismic Design, https://doi.org/10.1007/978-981-13-3176-3_5 135