Extensive data of the strength and dilatancy of 17 sands in axisymmetric or plane strain at different densities and confining pressures are collated. The critical state angle of shearing resistance of soil which is shearing at constant volume is principally a function of mineralogy and can readily be determined experimentally within a margin of about 1°, being roughly 33° for quartz and 40° for feldspar. The extra angle of shearing of ‘dense’ soil is correlated to its rate of dilation and thence to its relative density and mean effective stress, combined in a new relative dilatancy index. The data of o′max – o′crit in triaxial or plane strain are separately fitted within a typical margin of about 2°, though the streneth of certain sands is underpredicted in the 1000–10000 kN/m2 range owing to the continued dilation of their crush-resistant grains. The practical consequences of these new correlations are assessed, with regard to both laboratory and field testing procedures. L'auteur analyse de nombreuses d...

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The strength and dilatancy of sands

I wish to thank the British Geotechnical Society for the opportunity of visiting London’ again and for the honour of appearing before you in the home of the Institution of Civil Engineers, of which I am so proud to be a member. Several years ago I transmitted some preliminary notes on the topic of earthquake effects on dams to the late Karl Terzaghi, whose invaluable advice and suggestions regarding those notes were freely used in the preparation of this Paper. I wish also to acknowledge the comments and suggestions I have had from time to time concerning the subject from my colleague at the University of Illinois, Dr Ralph B. Peck ; from my associate in several consulting assignments, Dr Laurits Bjerrum ; and from my colleague for several months, while he was visiting the University of Illinois, Dr Tu’. N. Ambraseys. Finally, I should like to acknowledge the assistance on some of the calculations for this lecture that were made by two of my associates at the University of Illinois, Dr John W. Melin, and Mr Mohammad Amin.

Effects of Earthquakes on Dams and Embankments

https://www.icevirtuallibrary.com/doi/pdf/10.1680/geot.1965.15.2.139

The goal of this article is to revise several aspects of the well-known classification of landslides, developed by Varnes (1978). The primary recommendation is to modify the definition of landslide-forming materials, to provide compatibility with accepted geotechnical and geological terminology of rocks and soils. Other, less important modifications of the classification system are suggested, resulting from recent developments of the landslide science. The modified Varnes classification of landslides has 32 landslide types, each of which is backed by a formal definition. The definitions should facilitate backward compatibility of the system as well as possible translation to other languages. Complex landslides are not included as a separate category type, but composite types can be constructed by the user of the classification by combining two or more type names, if advantageous.

The Varnes classification of landslide types, an update

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

Significant factors affecting the liquefaction (or cyclic mobility) potential of sands during earthquakes are identified, and a simplified procedure for evaluating liquefaction potential which will take these factors into account is presented Available field data concerning the liquefaction or nonliquefaction behavior of sands during earthquakes is assembled and compared with evaluations of performance using the simplified procedure It is suggested that even the limited available field data can provide a useful guide to the probable performance of other sand deposits, that the proposed method of presenting the data provides a useful framework for evaluating past experiences of sand liquefaction during earthquakes and that the simplified evaluation procedure provides a reasonably good means for extending previous field observations to new situations When greater accuracy is justified, the simplified liquefaction evaluation procedure can readily be supplemented by test data on particular soils or by ground response analyses to provide more definitive evaluations

Simplified procedure for evaluating soil liquefaction potential

Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil. Values for the modulus coefficient at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35–2.5. Suggestions are also made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils.

Moduli and Damping Factors for Dynamic Analyses of Cohesionless Soils

The evolution of a simplified procedure for evaluating the liquefaction potential of sand deposits using data obtained from standard penetration tests is reviewed. Field data for sites which are known to have liquefied or not liquefied during earthquakes in the United States, Japan, China, Guatemala, Argentina, and other countries are presented to establish a criterion for evaluating the liquefaction potential of sands in Magnitude 7‐1/2 earthquakes. The results of this study are then extended to other magnitude earthquakes using a combination of laboratory and field data. Available information on the liquefaction resistance of silty sands is also reviewed and a simple procedure for considering the influence of silt content is proposed. A method is presented for using the field data to evaluate the possible magnitude of pore water pressure generation in sands and silty sands which remain stable during earthquake shaking. Finally, the applicability of other in situ field tests, such as the static cone pene...

Evaluation of Liquefaction Potential Using Field Performance Data

It is shown that the design engineer has two basic choices if he considers it appropriate to neglect the possible effects of drainage occurring during the period of cyclic stress applications: (1)To calculate the stresses induced in the ground by the design earthquake, and to compare these stresses with those required to cause cyclic mobility or liquefaction of representative samples in the laboratory. The main problem in this approach lies in correctly assessing the characteristics of the in-situ deposit from laboratory tests performed on even good quality undisturbed samples. (2)to be guided by the known field performance of sand deposits correlated with some measure of in-situ characteristics, such as the standard penetration test. In some cases it is desirable to evaluate the possible effects of pore pressure dissipation in different layers of a deposit during and following earthquake shaking. Methods of accomplishing this are reviewed and described.

H. Bolton Seed

Papers

Simplified procedure for evaluating soil liquefaction potential

Moduli and Damping Factors for Dynamic Analyses of Cohesionless Soils

Evaluation of Liquefaction Potential Using Field Performance Data

Soil Liquefaction and Cyclic Mobility Evaluation for Level Ground during Earthquakes

Closure to “Soil Liquefaction and Cyclic Mobility Evaluation for Level Ground during Earthquakes”