Particle breakage occurs when the stresses imposed on soil particles exceed their strength. To quantify the amount of breakage, many particle breakage factors have been proposed. Correlations of particle breakage parameters with standard soil parameters such as effective mean normal stress at failure and void ratio at failure do not provide a fully unified correlation with many different types of tests. However, particle breakage factors appear to correlate very well with the total energy input into the test specimen, thus providing a single unifying parameter for all types of soil tests. Therefore, the amount of particle crushing may be predicted if the stresses and strains in the soil can be estimated, such as in a finite-element analysis. The principal significant use of these particle breakage factors may be related to permeability estimates when there are changes in gradation due to particle breakage. A new particle breakage factor, B 10 , is proposed that will allow easy permeability computations wh...

Significance of particle crushing in granular materials

Porous Materials Water in Porous Materials Flow in Porous Materials Unsaturated Flows Unsaturated Flow in Building Physics Composite Materials Evaporation and Drying Topics in Water Transport Appendices Symbols Used Properties of Water Minerals, Salts and Solutions Other Liquids Other Data

Water Transport in Brick, Stone and Concrete

In this paper, intergranular (\Ie\dc\N) and interfine (\Ie\df\N) void ratios and confining stress are used as indices to characterize the stress-strain response of gap-graded granular mixes. It was found that at the same global void ratio (\ie) and confining stress, the collapse potential (fragility) of silty sand increases with an increase in fines content (FC) due to a reduction in intergranular contact between the coarse grains. Beyond a certain threshold fines content (FC\Dth\N), with further addition of fines, the interfine contact friction becomes significant. The fragility decreases and the soil becomes stronger. The value of FC\Dth\N depends on \ie and the characteristics of fines and coarse grains. At FC FC\Dth\N), fine grain friction plays a primary role and dispersed coarse grains provide a beneficial, secondary reinforcement effect. At the same \Ie\df\N, the collapse potential decreases with an increase in sand content. Beyond a certain limiting fines content, the soil behavior is controlled by \Ie\df\N, the collapse potential decreases with an increase in sand content. Beyond a certain limiting fines content, the soil behavior is controlled by \Ie\df\N only. An intergranular matrix diagram is presented that delineates zones of different behaviors of granular mixes as a guideline to determine the anticipated behavior of gap-graded granular mixes. New equivalent intergranular contact void ratios, (\Ie\dc\N)\Deq\N and (\Ie\df\N)\Deq\N, are introduced to characterize the behavior of such soils at FC FC\Dth\N, respectively.

Undrained Fragility of Clean Sands, Silty Sands, and Sandy Silts

Intrinsic self-sensing concrete and structures: A review

Electrically conductive cementitious composites carrying carbon fibers and carbon nanotubes were developed and their ability to sense an applied compressive load through a measureable change in resistivity was investigated. Two types of cement-based sensors, one with carbon fibers alone and the other carrying a hybrid of both fibers and nanotubes, were considered. Direct comparisons were also made with traditional strain gauges mounted on the sensor specimens. Sensing experiments indicate that under cyclic loading, the changes in resistivity mimic both the changes in the applied load and the measured material strain with high fidelity for both sensor types. The response, however, is nonlinear and rate dependent. At an arbitrary loading rate, the hybrid sensor, containing a combination carbon fibers and nanotubes, produced the best results with better repeatability.

Cement-based sensors with carbon fibers and carbon nanotubes for piezoresistive sensing

Des essais triaxiaux en compression non draines ont ete effectues sur des echantillons reconstitues de sable du Nevada et d'Ottawa, avec variation systematique de la teneur en fines (particules inferieures a 0,074 mm) afin d'evaluer l'effet de la fraction fine sur le potentiel de liquefaction statique lors d'un chargement monotonique. Les fines etaient non-plastiques. Les resultats indiquent clairement que la presence de fines peut augmenter considerablement le potentiel de liquefaction statique des quatre sables propres etudies lorsqu'on utilise la technique du montage a sec avec un entonnoir. Les fines semblent creer dans le sol une structure particulaire tres compressible ce qui accroit ainsi le potentiel de liquefaction alors meme que la densite augmente. Accroitre la teneur en fines d'un sable propre peut aboutir a l'augmentation du potentiel de liquefaction jusqu'a un seuil maximum pour lequel les fines dominent le comportement non draine du sol. A ce point la, le potentiel de liquefaction tend a devenir constant vis-a-vis de l'indice de densite. On a trouve que la liquefaction statique complete pouvait intervenir a un indice de densite superieur a 60% pour des teneurs en fines elevees.

Effects of nonplastic fines on static liquefaction of sands

The behavior of sand is affected by the content of nonplastic fine particles. How and to what degree the fines content affects the minimum and maximum void ratios has been studied in detail. A review is presented of previous theoretical and experimental studies of minimum and maximum void ratios of single spherical grains, packings of spheres of several discrete sizes, as well as optimum grain-size ratios to produce maximum densities. A systematic experimental study is performed of the variation of minimum and maximum void ratios with contents of fines for sands with smoothly varying particle size curves and a large variety of size distributions. It is shown that the fines content plays an important role in determining the sand structure and the consequent minimum and maximum void ratios. It is indicated how the fines content and sand structure affects the compressibility and the static liquefaction potential of the sand.

Effects of non-plastic fines on minimum and maximum void ratios of sand

On presente les resultats d'une etude experimentale menee sur deux sables differents. Des essais triaxiaux en compression, draines et non draines, ont ete effectues sur du sable du Nevada a quatre indices de densite initiaux differents, soient 12, 22, 31 et 42%. Des essais semblables ont ete faits sur du sable d'Ottawa a un indice de densite initial de 0%. Tous les essais ont suivi un chargement monotonique. A ces faibles densites on a obtenu un comportement anormal du materiau. Les essais triaxiaux en compression non draines ont abouti a une liquefaction statique complete (pression de confinement effective nulle et difference de contrainte nulle) sous des pressions de confinement faibles. Lorsqu'on augmente les pressions de confinement, les chemins de contraintes effectives indiquent une augmentation de la resistance a la liquefaction par une tendance plus marquee a la dilatance. Ceci est contraire au comportement normal d'un sol, ou augmenter la contrainte de confinement conduit a une attenuation de la dilatance. La presence de fines dans le sol (particules inferieures a 0,074 mm) a ete identifiee comme etant la cause probable de ce comportement. On a emis l'hypothese que les fines et les particules plus grosses creaient une structure granulaire ayant une compressibilite anormalement elevee a des pressions de confinement faibles. Les essais draines ont revele des contractions volumiques importantes qui en conditions non drainees se traduisent par des pressions interstitielles suffisamment elevees pour produire une liquefaction statique complete. Le comportement anormal peut se lire sur les angles de frottement draine aux faibles indices de densite qui augmentent d'abord avec la pression de confinement puis diminuent en suivant un processus normal.

Static liquefaction of very loose sands

The results from an experimental study on silty sands are presented and evaluated in view of the framework of critical-state or steady-state soil mechanics. Drained and undrained compression tests were performed on Nevada sand containing nonplastic silt. The drained and undrained steady-state lines diverged. This divergence was caused by the tendency for static liquefaction at low pressures. Results from undrained tests with different initial void ratios produced different steady-state lines. Unique steady-state lines may therefore not always exist for silty sands. Denser specimens liquefied at low confining pressures, while looser specimens at higher confining pressures showed stable behavior. Thus, a unique relation between void ratio and confining pressure, namely the steady-state line, may not represent the behavior of loose silty sands. This occurs because silty sands exhibit reverse behavior characteristics; more dilative behavior is observed with increasing confining pressure under undrained shearing. Load and deformation control testing was performed to evaluate the effect of strain rate. Compressibility was examined as an alternative measure of liquefaction potential.

Jerry A. Yamamuro

Papers

Significance of particle crushing in granular materials

Effects of nonplastic fines on static liquefaction of sands

Effects of non-plastic fines on minimum and maximum void ratios of sand

Static liquefaction of very loose sands

Steady-state concepts and static liquefaction of silty sands