Safety check of existing dam against altered seismic hazard conditions

The paper presents seismic hazard analysis of Gangrel dam situated in Chhattisgarh, India using CADAM. The static and seismic safety of existing concrete gravity dams is a continuous concern owing to the dynamic seismic activities due to the tectonic movement of the earth plates. These tectonic movements results in earthquakes and may alter the important seismic parameters like Peak Ground Acceleration (PGA). Earthquake actions are taken into account pseudo statically through inertia force characterized by a seismic coefficient. The design check of existing dam must be performed to assess whether seismic upgrading of a particular place is necessary from seismic safety point of view. According to NRC (1985) Dam safety must take precedence over all other considerations. CADAM software has been used for design check. Seismic analysis is done using the pseudo static method. Gangrel Dam, a major dam in CG state was constructed in the year 1979. Revised Seismic parameter, PGA for this site had been reported in the year 2006–07. With reference to altered value of PGA, seismic hazard analysis for Gangrel dam has been performed and presented through this paper. The Dam stability is checked for altered value of PGA for various loading conditions and it was found to be within safe limits presently.