Accession Number:

ADA214722

Title:

Re-Evaluation of the Lower San Fernando Dam; Report 2: Examination of the Post-Earthquake Slide of February 9, 1971

Descriptive Note:

Contract rept.

Corporate Author:

SEED (H BOLTON) INC ORINDA CA

Report Date:

1989-09-01

Pagination or Media Count:

269.0

Abstract:

Data from seismoscopes indicated that the main slide movements occurred about 20-30 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 in the soils comprising the embankment, rather than the inertial forces induced by the earthquake shaking, which led to the sliding of the upstream slope. Reproducibility of laboratory steady state strength test data was found to be very good. Results of undrained cyclic triaxial tests performed on undisturbed samples of hydraulic fill were found to be in good agreement with those of earlier studies. Standard penetration test SPT results from 1971 and 1985 field investigations, provided good agreement with the liquefaction resistance assessment based on cyclic tests of undisturbed samples, and by analogy provided a good assessment of observed pore pressure generation behavior of the hydraulic fill zones. Keywords Cyclic loading Earth dams Hydraulic fill Laboratory testing Residual strength Seismic stability Soil dynamics.

Subject Categories:

  • Soil Mechanics
  • Civil Engineering

Distribution Statement:

APPROVED FOR PUBLIC RELEASE