DYNAMIC ANALYSIS OF THE SLIDE IN THE LOWER SAN FERNANDO DAM DURING THE EARTHQUAKE OF FEBRUARY 9, 1971

Comments are made on the San Fernando Study, and the discrepancy between field and laboratory performance is discussed. It is suggested that the behavior of the upstream slope can be viewed without involving the concept of liquefaction. Only a relatively moderate eqrthquake- induced excess pore pressure is needed to explain post- earthquake slides for submerged slopes. The conventional procedures for dynamic testing are not aimed at developing data on residual pore pressure under dead loading although there appear to be no reasons why such information could not be generated in a slightly modified test program. But even this approach would have serious limitations because it seems likely that the actual failure mechanisim in the case of the Lower San Fernando Valley was the development of elevated pore pressures in the enterior of the slope followed by rapid migration of pressure outward along thin strata of coarse sand sandwiched between clay layers. This implies a condition of drained loading which is not permitted in the laboratory procedure. Also, the mechanisim of drainage depends on both large and small-scale conditions in the field which cannot possibly be simulated in the laboratory; this is a severe limitation on the usefulness of laboratory tests to predict such failures.

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  • Accession Number: 00133985
  • Record Type: Publication
  • Report/Paper Numbers: Proc. Paper #12052
  • Files: TRIS
  • Created Date: Jun 5 1976 12:00AM