Document: NUREG-0800
Document ID: 6d95bc89-e14a-4d87-bf91-1d1760c2aff8
Document Type: srp
Title: FOUNDATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1235/ML12353A388.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.5
CFR Part: 
CFR Title: 

Content:
r numerical (e.g., solid finite elements, distributed springs) formulations that are appropriate for the loading conditions as well as for the soil type, foundation type and size, and time scale being considered. In the case of seismic dynamic loads, the soil stiffness parameters should be consistent with the magnitude of soil strains assumed in the SSI analysis described in SRP Section 3.7.2, which are associated with the relatively short time scale of the seismic input. The distribution of toe bearing pressures used in foundation design should be consistent with the distribution of toe bearing pressures obtained from the SSI analysis. In the case of gravity loads and basemat foundations, the soil stiffness parameters should be consistent with: (a) dishing or Boussinesq effects (if uncoupled distributed springs are used then it may be necessary for the stiffness to be increased at the edges and reduced at the center of the basemat footprint); (b) basemat size (subgrade modulus could be highly dependent on basemat dimensions); (c) time scale of the loads (i.e., short term construction loads vs. long term loads present throughout the life of the structure); and (d) soil type (i.e., granular vs. cohesive soils). 3.8.5-12 Draft Revision 4 - December 2012 Appropriate stiffness parameters are particularly important when evaluating loads induced by the construction process and by differential settlements, as described in items E and J above. Additional guidance to consider in the review of DC and COL applications is given below. In the case of a DC application, the staff reviews the following information: • Postulated set of soil stiffness parameters for the construction phase and the technical bases for its selection, for all soils within the zone of influence surrounding the structures. The zone of influence is defined as that region to the side and below the structure that may induce loads on the structure if induced settlements occur and/or loads are applied within