Document: NUREG-0800
Document ID: c0d3006a-c4ee-4659-b650-837c0c94b143
Document Type: srp
Title: STABILITY OF SUBSURFACE MATERIALS AND FOUNDATIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340604.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.5.4
CFR Part: 
CFR Title: 

Content:
ace analysis method is used, when foundation moduli and damping are consistent with soil properties and soil profiles at the site. c. The static and dynamic loads, and the stresses and strains induced in the soil surrounding and underlying the structure are adequately and realistically evaluated. d. The consequences of the induced soil stresses and strains, as they influence the soil surrounding and underlying the structure, have been conservatively assessed. Subsection 2.5.4.8. In meeting the requirements of References 2, 3, 4, 6, and 7 and the regulatory positions of References 8, 10, and 11, if the foundation materials at the site adjacent to and under Category I structures and facilities are saturated soils and the water table is above bedrock, then an analysis of the liquefaction potential at the site is required. The need for a detailed analysis is determined by a study on a case by case basis of the site strati- graphy, critical soil parameters, and the location of safety-related founda- tions. Undisturbed samples obtained at the site and appropriate laboratory tests are required to show if the soils are likely to.liquefy. Liquefaction potential assessments using both deterministic and probabilistic approaches are desirable. When the need for an in-depth analysis is indicated, it may be based on cyclic triaxial test data obtained from undisturbed soil samples taken from the critical zones in the site area. The shear stresses induced in the soil by the postulated earthquake should be determined in a manner that is consistent with SRP Section 2.5.2. The criterion that should be used to determine when the soil samples tested "liquefied" should be taken as the onset of liquefaction (defined as the cycle when the pore pressure first equals the confining pressure). Test data showing the rate of pore pressure increase with number of load cycles should be presented. If the behavior of the pore pressure is such that peak to peak axial strains greater than a few