Following disastrous earthquakes in Alaska and in Niigata, Japan in 1964, Professors H. B. Seed and I. M. Idriss developed and published a methodology termed the ''simplified procedure'' for evaluating liquefaction resistance of soils. This procedure has become a standard of practice throughout North America and much of the world. The methodology which is largely empirical, has evolved over years, primarily through summary papers by H. B. Seed and his colleagues. No general review or update of the procedure has occurred, however, since 1985, the time of the last major paper by Professor Seed and a report from a National Research Council workshop on liquefaction of soils. In 1996 a workshop sponsored by the National Center for Earthquake Engineering Research (NCEER) was convened by Professors T. L. Youd and I. M. Idriss with 20 experts to review developments over the previous 10 years. The purpose was to gain consensus on updates and augmen- tations to the simplified procedure. The following topics were reviewed and recommendations developed: (1) criteria based on standard penetration tests; (2) criteria based on cone penetration tests; (3) criteria based on shear-wave velocity measurements; (4) use of the Becker penetration test for gravelly soil; (4) magnitude scaling factors; (5) correction factors for overburden pressures and sloping ground; and (6) input values for earthquake magnitude and peak acceleration. Probabilistic and seismic energy analyses were reviewed but no recommen- dations were formulated.

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Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils

Soils can rarely be described as ideally elastic or perfectly plastic and yet simple elastic and plastic models form the basis for the most traditional geotechnical engineering calculations. With the advent of cheap powerful computers the possibility of performing analyses based on more realistic models has become widely available. One of the aims of this book is to describe the basic ingredients of a family of simple elastic-plastic models of soil behaviour and to demonstrate how such models can be used in numerical analyses. Such numerical analyses are often regarded as mysterious black boxes but a proper appreciation of their worth requires an understanding of the numerical models on which they are based. Though the models on which this book concentrates are simple, understanding of these will indicate the ways in which more sophisticated models will perform.

Soil Behaviour and Critical State Soil Mechanics

Starting with specific constitutive equations, methods of evaluating material properties from experimental data are outlined and then illustrated for some polymeric materials; these equations have been derived from thermodynamic principles, and are very similar to the Boltzmann superposition integral form of linear theory. The experimental basis for two equations under uniaxial loading and the influence of environmental factors on the properties are first examined. It is then shown that creep and recovery data can be conveiently used to evaluate properties in one equation, while two-step relaxation data serve the same purpose for the second equation. Methods of reducing data to accomplish this characterization and to determine the accuracy of the theory are illustrated using existing data on nitrocellulose film, fiber-reinforced phenolic resin, and polyisobutylene. Finally, a set of three-dimensional constitutive equations is proposed which is consistent with nonlinear behavior of some metals and plastics, and which enables all properties to be evaluated from uniaxial creep and recovery data.

On the characterization of nonlinear viscoelastic materials

The electric cone penetration test (CPT) has been in use for over 40 years and is growing in popularity in North America. This paper provides some recent updates on the interpretation of some key g...

Interpretation of cone penetration tests — a unified approach

Note: Sols Reference LMS-ARTICLE-2004-001doi:10.1002/nag.332View record in Web of Science Record created on 2006-11-09, modified on 2016-08-08

Experimental study of thermal effects on the mechanical behaviour of a clay

Volume and pore water pressure variations that develop in saturated soils due to temperature changes are expressed in terms of the thermal expansion of the soil components, compressibility of the soil and physico-chemical effects. While the compression index of remolded illite was found independent of temperate, the higher the temperature the lower the void ratio at any given consolidation pressure. The magnitude of pore pressure change accompanying temperature change under undrained conditions is controlled primarily by the compressibility of the soil and thermal expansion of pore water. Results are useful for assessing the effects of temperature variations on properties of soils, the assessment of necessary laboratory temperature control during undrained tests, and the study of physico-chemical phenomena in soils.

Influence of Temperature Variations on Soil Behavior

Time dependence of undrained stress-strain and strength behavior of a natural sensitive marine clay has been investigated with particular reference to the effects of strain rate, strain rate history, aging, and thixotropy. Triaxial samples, identically consolidated, were sheared under a variety of time-loading histories in order to simulate various deformation rate histories. The stress-strain and strength results from these tests were correlated using the hypothesis that stress is a function of current strain and strain rate only. It is illustrated that a stiffer stress-strain response and an increase in undrained strength result from an increase in rate of strain, length of aging, and thixotropic hardening. However, the failure in terms of effective stresses is found to be independent of time effects of any kind whatsoever.

Time-Dependent Behavior of Undisturbed Clay

The fundamental equation of the theory of absolute reaction rates has been adapted for use in the study of time-dependent soil deformations. Results of constant stress creep tests have established that the basic form of this equation supports the assumption of a thermally activated creep process, the predicted relationship between experimental activation energy and creep stress, and the predicted stress dependence of creep rate. Some modification of the equation is needed, however, to account for the variation of creep rate with time. Techniques are described for study of deformation mechanisms in soils and test results suggest that interparticle bonding is probably of the primary valence type. Resistance to shear stresses cannot be accounted for in terms of viscous water films, and interparticle contacts must be effectively solid to solid.

Soil creep as a rate process

Dissipation of excess pore pressures during piezocone testing in firm to stiff overconsolidated fine-grained soils provides data curves that cannot be interpreted using published theoretical soluti...

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An approach to evaluation of field CPTU dissipation data in overconsolidated fine-grained soils

One of the primary objectives of the Canadian Liquefaction Experiment (CANLEX) project was to evaluate in situ testing techniques and existing interpretation methods as part of the overall goal to ...

R. G. Campanella

Papers

Influence of Temperature Variations on Soil Behavior

Time-Dependent Behavior of Undisturbed Clay

Soil creep as a rate process

An approach to evaluation of field CPTU dissipation data in overconsolidated fine-grained soils

Interpretation of in situ test results from the CANLEX sites