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

Over the past decade, major advances have occurred in both understanding and practice with regard to assessment and mitigation of hazard associated with seismically induced soil liquefaction. Soil liquefaction engineering has evolved into a sub-field in its own right, and engineering assessment and mitigation of seismic soil liquefaction hazard is increasingly well addressed in both research and practice. This rapid evolution in the treatment of liquefaction has been pushed largely by a confluence of lessons and data provided by a series of major earthquakes over the past dozen years, as well as by the research and professional/political will engendered by these major seismic events. The overall field of soil liquefaction engineering is now beginning to coalesce into an internally consistent and comprehensive framework, and one in which the various elements are increasingly mutually supportive of each other. Although the rate of progress has been laudable, further advances are occurring, and more remains to be done. As we enter a “new millenium”, engineers are increasingly well able to deal with important aspects of soil liquefaction engineering. This paper will highlight a number of important recent and ongoing developments in soil liquefaction engineering, and will offer insights regarding research in progress, as well as suggestions regarding further advances needed. 1 Dept. of Civil and Environmental Engineering, University of California, Berkeley. 2 Dept. of Civil Engineering, Middle East Technical University, Ankara, Turkey. 3 Fugro Engineering, Santa Barbara, California. 4 Arup, San Francisco, California. 5 URS Corporation, Oakland, California. 6 U.S. Geological Survey, Menlo Park, California. 1.0 INTRODUCTION Soil liquefaction is a major cause of damage during earthquakes. “Modern” engineering treatment of liquefactionrelated issues evolved initially in the wake of the two devastating earthquakes of 1964; the 1964 Niigata (Japan) and 1964 Great Alaskan Earthquakes. Seismically-induced soil liquefaction produced spectacular and devastating effects in both of these events, thrusting the issue forcefully to the attention of engineers and researchers. Over the nearly four decades that have followed, significant progress has occurred. Initially, this progress was largely confined to improved ability to assess the likelihood of initiation (or “triggering”) of liquefaction in clean, sandy soils. As the years passed, and earthquakes continued to provide lessons and data, researchers and practitioners became increasingly aware of the additional potential problems associated with both silty and gravelly soils, and the important additional issues of post-liquefaction strength and stressdeformation behavior also began to attract increased attention. Today, the area of “soil liquefaction engineering” is emerging as a semi-mature field of practice in its own right. This area now involves a number of discernable sub-issues or subtopics, as illustrated schematically in Figure 1. As shown in Figure 1, the first step in most engineering treatments of soil liquefaction continues to be (1) assessment of “liquefaction potential”, or the risk of “triggering” (initiation) of liquefaction. There have been major advances here in recent years, and some of these will be discussed. Once it is determined that occurrence of liquefaction is a potentially serious risk/hazard, the process next proceeds to assessment of the consequences of the potential liquefaction. This, now, increasingly involves (2) assessment of available post-liquefaction strength, and resulting post-liquefaction overall stability (of a site, and/or of a structure or other built facilities, etc.). There has been considerable progress in

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Recent Advances in Soil Liquefaction Engineering: A Unified and Consistent Framework

This report presents information on the characterization of cementitiously stabilized layers and the properties that influence pavement performance. It also contains recommended performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic–empirical pavement analysis methods. Individual chapters highlight pavement distresses of hot-mix asphalt pavements and concrete pavements, laboratory tests and model development, and model calibration. The material contained in the report will be of immediate interest to state materials, pavement, and construction engineers and others involved in the different aspects of pavement design and construction.

Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis

Sand response depends on particle morphology (size and shape). In geotechnical research and practice, size is typically assessed by sieve analysis and particle shapes are qualitatively described. Technological developments mean that digital images of sand particles can easily be obtained, enabling shape to be quantified. The complexity associated with many digital image analysis algorithms seems to have restricted their use to fundamental research studies. This study introduces a pragmatic approach for quantitative shape analysis that has the potential to be broadly adopted in geotechnical engineering research and practice. The approach generates three shape measures (convexity, sphericity, and aspect ratio) that can easily be calculated from digital images. Following an analysis of these shape measures and the imaging method used here, a database of 36 sands, including many of the sands commonly used in geotechnical research, is presented. The subjective nature of qualitative description is clear...

Analysis of an Image-Based Method to Quantify the Size and Shape of Sand Particles

A soil classification system is used to group soils according to shared qualities or characteristics based on simple cost-effective tests. The most common soil classification systems used in geotechnical engineering are based on physical (textural) characteristics such as grain size and plasticity. Ideally, geotechnical engineers would also like to classify soils based on behaviour characteristics that have a strong link to fundamental in situ behaviour. However, existing textural-based classification systems have a weak link to in situ behaviour, since they are measured on disturbed and remolded samples. The cone penetration test (CPT) has been gaining in popularity for site investigations due to the cost-effective, rapid, continuous, and reliable measurements. The most common CPT-based classification systems are based on behaviour characteristics and are often referred to as a soil behaviour type (SBT) classification. However, some confusion exists, since most CPT-based SBT classification systems use te...

Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update

Un objectif principal du projet canadien d'etude de la liquefaction (Canadian Liquefaction Experiment, CANLEX) etait de verifier les procedures d'analyse pour la prediction des phenomenes de liquefaction. A cette fin, deux cas de chargement ont ete realises: un chargement sur le terrain comprenant un remblai construit sur une couche de fondation de sable lâche, et un essai au centrifuge realise sur un modele de la structure prototype. Tant l'essai sur le terrain que l'essai au centrifuge ont ete planifies de facon a induire une rupture par liquefaction statique. Les caracteristiques mecaniques fondamentales de la couche de fondation ont ete determinees dans des essais en laboratoire sur des elements (triaxiaux et cisaillement simple). Ces caracteristiques ont ete d'abord obtenues sur un element en utilisant un modele de comportement contrainte-deformation elasto-plastique. Le prototype et les structures a l'echelle ont alors ete modelises comme un ensemble de tels elements. Le drainage etait un facteur tres important durant le chargement et etait directement incorpore dans la procedure de l'analyse. Les resultats predits concordent bien tant avec l'essai au centrifuge qu'avec les mesures sur le terrain.

Analysis of CANLEX liquefaction embankments: prototype and centrifuge models

Cyclic loading response of loose Fraser River sand was investigated, as input to numerical simulation of centrifuge physical models, using constant-volume direct simple shear tests conducted with a...

Cyclic loading response of loose air-pluviated Fraser River sand for validation of numerical models simulating centrifuge tests

An Effective Stress Model for Pedicting Liquefaction Behaviour of Sand

This paper presents results from a series of model tests of single vertical piles subjected to lateral monotonic pile head loading. Model tests were carried out in sand under a simulated field stre...

Lateral pile response to monotonie pile head loading

Pile reponse to earthquake loading and soilpile interaction behaviour were investigated experimentally using the hydraulic gradient similitude technique. The unique feature of this method is the a...

Peter M. Byrne

Papers

Analysis of CANLEX liquefaction embankments: prototype and centrifuge models

Cyclic loading response of loose air-pluviated Fraser River sand for validation of numerical models simulating centrifuge tests

An Effective Stress Model for Pedicting Liquefaction Behaviour of Sand

Lateral pile response to monotonie pile head loading

Dynamic response of single piles and soilpile interaction