Starting in 1990, Nuclear Electric Ltd (NEL), now EDF Energy, carried out a thorough review of the dynamic properties of a number of their nuclear power station sites. The catalyst for the review was the publication of a number of studies of site response during real earthquakes; considerable advances in measuring and understanding the non-linearity of soil deformation under static loading, impacting on their response under repetitive dynamic loading; and information from modern ground investigations had been acquired during the 1980’s for a number of NEL’s sites.
NEL awarded a contract to GCG to assess the bending moments, shear forces and deformations in the reinforced concrete raft supporting the Reactor Building of the Dungeness ‘B’ Nuclear Power Station which first generated power in early 1983. The Reactor Building includes two Prestressed Concrete Pressure Vessels and the Fuel Handling Unit. After interpreting the information on foundation construction, ground conditions and measured settlement, GCG devised a method of modelling the raft, using the finite element (FE) code ICFEP. Various load cases were simulated, initially using two dimensional FE analyses and later using three dimensional FE analyses. The analyses examined the behaviour of the raft under static and seismic loading, modelling the interaction between the raft and its supporting foundation. The predicted distortion and total settlement of the raft obtained from the 3D analyses were in good agreement with those measured, indicating that the model would be appropriate when considering other loading conditions.