Proceeding of the NCEER workshop on evaluation of liquefaction resistance of soils

ABSTRACT

Over the past twenty-five years, a procedure, termed the "simplified procedure" has evolved for evaluating liquefaction resistance of soils. This procedure has become the standard of practice in North American and trougthout much of the world. The purpose of the 1996 workshop, sponsored by the National Center for Earthquake Engineering Research (NCEER) was to convene a group of experts to review developments and gain consensus for furher augmentations to the procedure. To keep the workshop focused and the content tractable, the scope was limited to evaluation of liquifaction resistance. Post-liquefaction phenomena, such as soil deformation and ground failure, although equally or more important, were beyond the scope of this workshop. The participants developed consensus recommendations on the following topics (1) use of the standard and cone penetration tests for evaluation of liquefaction resistance, (2) use of shear ware velocity measurements for evaluation of liquefaction resistance, (3) use of the Becker penetration test for gravelly soils, (4) magnitude scaling factors, (5) correction factors K and K, and (6) evaluation of seismic factors required for the evaluation procedure. Probabilistic analysis and seismic energy considerations were also reviewed. Seismic energy conceptss were judged to be insufficiently developed to make recommendations for engineering practice. Probabilistic methods have been used in some risk analyses, but are still outside the mainstream of standard practice. (AU)