Re-Evaluation of the Lower San Fernando Dam. Report 2. Examination of the Post-Earthquake Slide of February 9, 1971
Abstract
Data from seismoscopes located on the crest and an abutment indicated that the main slide movements occurred about 20 to 30 sec after the strong earthquake shaking had stopped. It can thus be inferred that the earthquake shaking triggered a loss of strength in the soils comprising the embankment, and that it was this loss of strength, rather than the inertial forces induced by the earthquake shaking, which led to the sliding of the upstream slope. The present studies were performed to: a) determine whether recently developed techniques for evaluating in-situ undrained steady state strength based on laboratory testing and post-test corrections would accurately predict the observed residual strength of the San Fernando Dam hydraulic fill materials; b) determine whether use of improved sampling procedures would lead to different results for undrained cyclic load tests on 'undisturbed' samples taken from the dam (relative to those obtained in earlier investigations in 1971-73; c) explore the reproducibility of laboratory steady state strength test data used for seismic stability evaluations as measured in different laboratories; and d) evaluate the feasibility of basing both pore pressure generation ('triggering') and undrained residual strength (post-triggering stability) assessments on Standard Penetration Test (SPT) data using new standardized SPT procedures. Earth dams. (edc)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1989
- Accession Number
- ADA214427
Entities
People
- H. B. Seed
- Hsing-lian Jong
- Leslie F. Harder
- Raymond B. Seed