Seismic site characterization for nuclear structures and power plants

Seismic site characterization is carried out for the construction of nuclear structures and power plants in earthquake-prone areas to establish the occurrence of severe seismic hazards such as tectonic rupture, surface faulting, large scale liquefaction, sliding and seismic settlement which may alter the overall stability of the site. Seismic characterization is required to finalize the design earthquake parameters including choosing input seismic data. As a part of the investigation, measurements of relevant dynamic parameters both in laboratory and in situ have been made for carrying out dynamic soil structure interaction analysis, for determination of dynamic deformation, seismic settlement and dynamic response spectrum of the site, and for calculating dynamic earth pressure acting on retaining structures. We discuss here the seismic investigation components and methods, measurement of P- and S-wave velocities in the field and estimation of important dynamic parameters such as maximum shear modulus, modulus reduction curve, damping ratio, seismic site classification, predominant site period, liquefaction analysis through case studies for nuclear structures at Kalpakkam and Kudankulam and power plant structures at New Delhi and Konaseema.