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This study addressed the characteristics of lateral pile-soil interactions in coral sand foundation using a series of direct shear, triaxial, and model pile tests. Through the comprehensive analysis of the stress state of the coral sand around pile, it was found that the soil resistance is mainly dominated by frontal squeezing resistance. Accordingly, the framework of the modified p-y model was determined, namely the function type, exponents of depth term, and the mark of entering the plastic state. The modified p-y model adopts a normalized dimensionless form, and it is composed of the first nonlinear segment represented by the power function and the plastic state at large displacements represented by a straight line. The final p-y model was calibrated using the results of the model pile test. Subsequently, the validity of the modified p-y model was verified by the experimental results of this study and other researchers. The soil reactions and pile responses predicted by the modified p-y model were in a reasonable agreement with the measured data. Finally, the modified p-y model was compared with the existing p-y models, thus confirming its rationality and applicability. Key words: coral sand, p-y curve, direct shear test, triaxial test, model pile test, Introduction Pile foundations are commonly used to resist the lateral loads applied to structures (Luan et al. 2020a, 2020b). To date, several approaches are available to determine the behavior of [...]

Dual row retaining walls can form efficient port and embankment structures, or even be used as coastal defence against tsunamis. The system of parallel sheet pile walls can have a large lateral capacity within serviceability limit states due to the combined strength and stiffness of the walls and confined soil. Optimising the design by reducing the wall section and ensuring greater utilisation of the soil capacity has economic and environmental benefits but requires a deeper understanding of the dynamic soil-structure interaction. Centrifuge modelling and numerical modelling are used to elucidate the mechanics of two systems with relatively flexible and stiff walls. Considering the fraction of the wall's plastic moment capacity mobilised alongside the peak deflections illustrates the advantages of using relatively flexible retaining walls in these systems. More fundamentally, the importance of vertical variations of both the stress and strain during the horizontal dynamic loading is shown. The limiting horizontal stresses and phasing of the stress components around the walls are better understood by considering the mobilisation of earth pressure coefficients, reinforcing previous work that recommends a move away from conventionally defined limiting dynamic earth pressure coefficients. Key words: centrifuge modelling and numerical modelling, dynamic earth pressure coefficient, earth pressure phasing, earthquakes, retaining walls. Les murs de soutenement a deux rangees peuvent former des structures portuaires et des remblais efficaces, ou meme etre utilises comme defense cotiere contre les tsunamis. Le systeme de parois de palplanches paralleles peut avoir une grande capacite laterale dans les etats limites de fonctionnement en raison de la resistance et de la rigidite combinees des parois et du sol confine. Optimiser la conception en reduisant la section des murs et en assurant une meilleure utilisation de la capacite du sol presente des avantages economiques et environnementaux, mais necessite une meilleure comprehension de l'interaction dynamique entre le sol et la structure. La modelisation centrifugeuse et la modelisation numerique sont utilisees pour elucider la mecanique de deux systemes aux parois relativement souples et rigides. La prise en compte de la fraction de la capacite de moment plastique des murs mobilisee a cote des deflexions de pointe illustre les avantages de l'utilisation de murs de soutenement relativement flexibles dans ces systemes. Plus fondamentalement, l'importance des variations verticales de la contrainte et de la deformation pendant la charge dynamique horizontale est demontree. Les contraintes horizontales limitatives et le phasage des composantes des contraintes autour des murs sont mieux compris en considerant la mobilisation des coefficients de pression des terres, ce qui renforce les travaux anterieurs qui recommandent de s'eloigner des coefficients de pression des terres dynamiques limitatifs definis de maniere conventionnelle. [Traduit par la Redaction] Mots-cles: modelisation centrifugeuse et modelisation numerique, coefficient dynamique de pression terrestre, phasage de la pression terrestre, tremblements de terre, murs de soutenement., 1. Introduction Dual row retaining walls, formed by two parallel rows of sheet pile walls connected by tie rods at the wall heads and with a sand infill, are novel [...]

Plate anchors are among the most effective anchorage systems that are widely used to resist horizontal and inclined uplift loads in many offshore and onshore applications. Previous research on plate anchors has largely focused on the horizontal or vertical breakout problems, with limited attention directed towards obtaining a full characterization of the effects of anchor orientation angle. The present study utilizes displacement-based finite element analyses to investigate the stability and performance of strip anchor embedded in cohesionless soil for plate inclination angles ranging from 0[degrees] to 90[degrees] from horizontal, where the applied load is normal to and acts at the center of the plate. This study investigates the effects of scale and roughness, along with the geometry of the failure mechanism for various plate orientations and embedment depths. The analyses, presented in terms of a non-dimensional breakout factor [N.sub.q], show that the breakout factor increases significantly with an increase in the inclination, especially for angles greater than 45[degrees] in loose sand and greater than 60[degrees] in dense sand. The analyses also show that scale effects (anchor width) can affect capacity. Finite element analyses have been used to introduce simple design charts relating the breakout factor to the embedment depth and relative density. Comparisons to experimental and numerical studies showed good agreement. Key words: plate anchors, breakout capacity, finite element analysis. Les ancrages a plaque sont parmi les systemes d'ancrage les plus efficaces qui sont largement utilises pour resister aux charges de soulevement horizontales et inclinees dans de nombreuses applications en mer et sur terre. Les recherches anterieures sur les ancrages a plaque se sont largement concentrees sur les problemes de rupture horizontale ou verticale, avec une attention limitee portee a l'obtention d'une caracterisation complete des effets de l'angle d'orientation de l'ancrage. La presente etude utilise des analyses par elements finis basees sur le deplacement pour etudier la stabilite et la performance d'un ancrage a bande noye dans un sol sans cohesion pour des angles d'inclinaison de la plaque allant de 0[degrees] a 90[degrees] par rapport a l'horizontale, ou la charge appliquee est normale et agit au centre de la plaque. Cette etude etudie les effets de l'echelle et de la rugosite, ainsi que la geometrie du mecanisme de rupture pour differentes orientations de plaques et profondeurs d'encastrement. Les analyses, presentees sous la forme d'un facteur de rupture non dimensionnel [N.sub.q], montrent que le facteur de rupture augmente sensiblement avec l'augmentation de l'inclinaison, en particulier pour les angles superieurs a 45[degrees] dans le sable meuble et superieurs a 60[degrees] dans le sable dense. Les analyses montrent egalement que les effets d'echelle (largeur de l'ancre) peuvent affecter la capacite. Les analyses par elements finis ont ete utilisees pour introduire des graphiques de conception simple reliant le facteur de rupture a la profondeur d'encastrement et a la densite relative. Des comparaisons avec des etudes experimentales et numeriques ont montre un bon accord. [Traduit par la Redaction] Mots-cles: ancrage des plaques, capacite de rupture, analyse par elements finis., Introduction Soil anchors are widely used to resist uplift and lateral forces for various offshore and onshore structures such as transmission towers, sheetpiles, retaining walls, subsea pipelines, and floating structures. [...]

Cable ploughing is an important technique for burying and protecting offshore cables. The ability to predict the required tow force and plough performance is essential to allow vessel selection and project programming. Existing tow force models require calibration against full-scale field testing to determine empirical parameters, a requirement that may hinder their use. In this study the factors controlling the plough resistance were investigated using a series of dry and saturated 1/50th scale model cable plough tests in sand in a geotechnical centrifuge at 50 g at a range of target trench depths, sand relative densities, and plough velocities. An improved model for predicting cable plough tow force that separates out the key components of resistance and allows tow force prediction without the use of field-derived empirical coefficients is presented. It is demonstrated that the key parameters in this model can be easily determined from in situ cone penetration tests (CPTs), allowing it to be used offshore where site investigation techniques may be more limited compared to onshore locations. The model is validated against the centrifuge cable plough tests, demonstrating it can correctly predict both the static (dry) and rate effect (saturated) tow forces. Key words: cable ploughing, cone penetration test (CPT), sand, centrifuge modelling, rate effects, offshore. Le labourage des cables est une technique importante pour enfouir et proteger les cables en mer. La capacite de prevoir la force de remorquage et les performances de la charrue est essentielle pour permettre la selection des navires et la programmation des projets. Les modeles de force de remorquage existants doivent etre etalonnes par rapport a des essais sur le terrain en grandeur reelle pour determiner les parametres empiriques, ce qui peut entraver leur utilisation. Dans cette etude, les facteurs controlant la resistance de la charrue ont ete etudies a l'aide d'une serie d'essais de charrue a cable a l'echelle 1/50eme, seche et saturee, dans du sable dans une centrifugeuse geotechnique a 50g, a differentes profondeurs de tranchees, densites relatives de sable et vitesses de charrue. Un modele ameliore de prevision de la force de traction des charrues a cable, qui separe les principales composantes de la resistance et permet de prevoir la force de traction sans utiliser de coefficients empiriques derives du terrain, est presente. Il est demontre que les parametres cles de ce modele peuvent etre facilement determines a partir d'un essai de penetration au cone (CPT) in situ, ce qui permet de l'utiliser en mer ou les techniques d'investigation du site peuvent etre plus limitees qu'a un emplacement terrestre. Le modele est valide par rapport aux essais de charrue a cable en centrifugeuse, demontrant qu'il peut predire correctement les forces de traction statiques (seches) et a effet de vitesse (saturees). [Traduit par la Redaction] Mots-cles: labourage par cable, essai de penetration au cone (CPT), sable, modelisation par centrifugeuse, effets de taux, en mer., Introduction Cable burial is a key method for the protection of offshore cables from hazards (BERR 2008) and installation of seabed cables may be undertaken by different means depending on [...]

Most coastal communities in the United States test the water at beaches for the presence of bacteria. But they don't routinely test the sand. Does sand also harbor bacteria? Until [...]

The Bolson sand sheet occurs in the Tularosa Valley, New Mexico, and the Hueco Bolson, Texas and consists of two principal eolian sand units. Optically stimulated luminescence (OSL) dating provides a new chronology of the sand sheet that relates as well to the formation, preservation, and visibility of the local archaeological record. The lower sand (unit Q2) (44.8 [+ or -] 2.9 ka) and the upper sand (unit Q3) (22.2 [+ or -] 1.6-5.2 [+ or -] 0.3 ka) have a combined thickness of less than 2 m. The Q2 sand is characterized by a red Bt paleosol, and the Q3 sand has a weak calcic paleosol with stage I carbonate morphology. Elevated amounts of airborne silt were incorporated in the Q3 sand during the period 2414.5 ka, representing higher amounts of dust in the atmosphere during glacial and lateglacial time. Multiple OSL ages from the Q3 sand indicate a slow net sedimentation rate of 0.06-0.09 mm/yr, similar to other OSL-dated sand sheets in the region; sand deposits in dune fields have higher accumulation rates. The McGregor A horizon soil, radio-carbondated to younger than 0.5 ka, occurs at the top of the sand sheet and likely formed with desert grassland vegetation. Thousands of recent mesquite coppice dunes (unit Q4d) mantle the sand sheet, and two are dated to the twentieth century by OSL and [sup.137]Cs. Archaeological sites that postdate 3000 B.C. are concentrated, sometimes together, on the surface of the sand sheet, while sites that pre-date 3000 B.C., although rare, may be buried within the Q3 eolian sand. The Q2 sand is too old to contain archaeological sites, although site features may intrude into the sand. Previous chronologies of the sand sheet are based on radiocarbon dates of charcoal from archaeological sites, on radiocarbon dates of soil carbonate, and on soil-geomorphology correlations with Rio Grande Valley alluvium. The optical chronology does not support these various correlations. We recommend that the alluvial names Isaacks' Ranch, Fillmore, and Organ no longer be applied to the Bolson sand sheet. doi: 10.1130/B30173.1

The record of terrestrial meteorite impacts is fragmentary because most impact structures and ejecta are removed by erosion or buried. Discovery of the missing impact record from Hadean to present may be advanced through identification of residual shocked detritus. To evaluate which shocked minerals survive erosion and sedimentary transport, we investigated modern sands from the Vaal River in South Africa, where it crosses the 2.02 Ga Vredefort Dome, the largest terrestrial impact structure known to date. Shocked minerals were identified in all sediment samples, including from the Vaal channel and tributaries within the structure. In transmitted light, detrital quartz preserves discontinuous decorated planar features previously identified as Brazil twins, which are readily visible as bright, continuous features in cathodoluminescence images. Detrital zircons preserve five orientations of planar fractures (PFs), which can produce dramatically offset growth zoning and apparent rotation of subgrains. Other zircons contain filled fractures that may represent a new shock microstructure. Detrital monazite preserves four orientations of PFs, and many grains contain oscillatory-zoned shocked zircon inclusions, which thus represent shocked inclusions within shocked accessory grains. Zircon and monazite with granular texture were also identified. This study is proof of the concept that shocked minerals can be identified in sediments up to 2 billion years after an impact event, and it demonstrates their potential for preserving evidence of ancient impacts. The recognition of a new geological repository for impact evidence provides a means for identifying distal shocked detritus from eroded structures of any age, and may be particularly relevant to early Earth studies. doi: 10.1130/B30187.1

An adjustable shear stress straight flume commonly used to measure cohesive sediment erosion rates has been modified to include downstream bed load traps. The new flume can be used not only to measure erosion rates, but also to analyze and quantify the modes of transport for this complex problem. The new device was used to study transport modes of quartz particles ranging in size from 19 to 1,250 [micro]m. As expected, the traps captured the coarse material (bed load) and the fine material bypassed the traps (suspended load). Transport properties of natural sediments from three locations were also studied. Fine sediments with little or no sand eroded as aggregates which maintained their integrity in the flume channel while moving as bed load into the traps. Natural sediments that included high percentage of sand also eroded as aggregates. However, these aggregates quickly disaggregated. Sand moved as bed load and fell into the traps while fine particles moved predominately in suspension. DOI: 10.1061/(ASCE)WW.1943-5460.0000054 CE Database subject headings: Bed loads; Sediment; Sand, hydraulic; Silts; Suspended loads. Author keywords: Bed load; Sediment; Sand; Silt; Separation; Transport; Suspension.

Observations on outcrop of a regionally developed sand injectite are used to infer and estimate the pore-pressure conditions in the shallow crust that caused the fluidization and injection of tens of cubic kilometres of sand. The estimated pore-fluid pressures at the base of the injection complex (at 1500 m burial depth, below a regionally developed shale-dominated seal) are from 22.26 to 25.08 MPa, which respectively correspond to 0.81 and 0.95 lithostatic pressure. A theoretical basis for prediction of sand injection is defined and applied to the prediction of pore pressure at the time of sand injection, the depth at which seal failure occurred, and the density and granular content of the fluidized flow. Lateral variations in the style and abundance of sandstone intrusions are described and these all fit into a remarkably uniform tripartite division of parent units, an intrusive complex and an extrusive complex. A sill zone (intrusions are dominated by sills) occurs in a restricted stratigraphic interval 200-270 m thick. Location of the base of the sill zone is directly related to the thickness of the overburden, and an isobaric surface at the time of sand injection, the lithostatic equilibrium surface, is defined at the base of the sill zone. When the sills formed an extended period of supralithostatic pressure occurred within the sill zone. doi: 10.1144/0016-76492010-004.

The behavior of shallow foundations resting on laterally and (or) vertically confined sand has been investigated using physical and numerical modeling. The models were designed to simulate the frequently constructed raft foundations that are surrounded by sheet-pile walls to support excavation sides of sand underlain by a rock bed. Laboratory tests were carried out utilizing a square foundation model surrounded by rigid steel walls with different depths, resting on sand that was underlain by a rough rigid layer. Varying sand-layer thicknesses and relative densities were utilized. A three-dimensional finite element analysis was conducted to verify the physical-model test results and to infer the performance of full-scale foundations. Based on the results of the experimental and numerical analyses, charts are presented to estimate the enhanced bearing capacity of square foundations resting on confined sand. These charts are presented in terms of bearing capacity of the surface foundation resting on extended sand, sand relative density, wall width to foundation width ratio, and rigid layer depth. Charts are also presented to estimate settlement reductions due to the bearing sand lateral and (or) vertical confinement. Key words: sand confinement, shallow foundation, bearing capacity, settlement, relative density. Le comportement de fondations peu profondes place sur du sable confine lateralement et/ou verticalement est generalement investigue a l'aide de la modelisation physique et numerique. Les modeles ont ete concus pour simuler les radiers qui sont entoures de murs en palplanche pour supporter les bords d'une excavation de sable au-dessus du roc. Des essais en laboratoire ont ete effectues a partir d'un modele de fondations carrees, entouree de murs d'acier rigides a differentes profondeurs, depose sur du sable place sur une surface rugueuse rigide. Differentes epaisseurs de la couche de sable et densites relatives du sable ont ete utilisees. Une analyse d'elements finis en trois dimensions a ete realisee pour verifier les resultats de du modele physique et pour deduire la performance des fondations pleines grandeur. A partir des resultats experimentaux et des analyses numeriques, des graphiques servant a estimer l'augmentation de la capacite portante de fondations carrees deposees sur du sable confine sont presentes. Ces graphiques sont presentees en termes de la capacite portante d'une fondation de surface placee sur du sable, la densite relative du sable, le ratio de la largeur du mur sur la largeur de la fondation, et la profondeur de la couche rigide. Les graphiques servent aussi a estimer les reductions de tassement dues au sable lateral portant et/ou au confinement vertical. Mots-cles : confinement du sable, fondation peu profonde, capacite portante, tassement, densite relative. [Traduit par la Redaction], Introduction Significant change is expected in the behavior of shallow foundations due to confinement of the bearing sand. Footings with rigid sheet piles fixed at their circumference (i.e., skirted foundations) [...]

The main mineralogical/lithological composition of the Varzaneh aeolian sands is sedimentary and igneous lithics. The minor one is metamorphic lithics and mineral grains (such as quartz, feldspar and heavy mineral grains) respectively. The origin of the sedimentary lithics (mainly carbonates) mostly is from sedimentary rocks exposed in the west and the southwest of the study area. These rocks belong to Cretaceous and Jurassic outcrops. The origin of the igneous lithic grains chiefly belongs to Tertiary highlands, located to the north and the northeast of the study area. The main origin of the metamorphic lithic grains is from the mountain ranges located in the north-western and the western part of the drainage basin of the Zayandeh river. Texture of the aeolian sand grains is similar to the Zayandeh river sediments. Concentration of the aeolian sands at the west of the Zayandeh river delta, variation of their mineralogical/lithological composition from north to south, and textural characterizations of sand grains indicate that the water laid sediments of the Zayandeh river, widespread to the north of the aeolian sands, are the main supply of the aeolian sands and sediments deposited by the two ephemeral streams in the south and the southwest of the sand dunes are minor one. Key words: aeolian sand, lithic grains, mineralogical composition, texture, sediments, INTRODUCTION The term provenance, in general, refers to a location of origin, where the sediments are derived from, and the nature of source rocks (2). In provenance studies, however, it [...]

Five Austin-style sand filters were constructed by the California Department of Transportation (CALTRANS) as retrofit projects for maintenance yards and park-and-ride facilities in the Los Angeles and San Diego metropolitan areas. Each of these filter systems included storm-water monitoring equipment for collection of flow weighted composite samples. In addition, detailed records were compiled of the design elements, construction costs, and type and amount of maintenance required at each of the sites. The construction costs were relatively high because of the retrofit nature of the project and the integration of the CALTRANS storm-drain system with those of the adjoining metropolitan areas, which eliminated any opportunities for economies of scale. An analysis of performance using linear-regression techniques indicated that for sediment and almost all particle associated constituents, effluent concentration was independent of influent concentration. For instance, the average suspended solids concentration in treated runoff was 7.8 [+ or -] 1.2 mg/L (at the 90% confidence level) regardless of observed influent concentration. The constant effluent quality produced for the particulate constituents indicates that the calculation of a percent reduction is more indicative of the influent concentration rather than the performance of the filter itself. Rejuvenation of the filter bed was required at three sites after 3 years of operation when the solids loading to the system was between 5 and 7.5 kg/[m.sup.2] of filter area. However, the clogging may have been accelerated by problems with the pumps that resulted in standing water on the filter for extended periods. Other maintenance activities consisted mainly of inspections, pump repair, and activities to reduce mosquito breeding. The main impediment to widespread implementation is the initial construction cost; however, modifications of the filter configuration and media may reduce these costs and increase effectiveness, thereby making the technology more attractive. DOI: 10.1061/(ASCE)0733-9496(2003)129:3(234) CE Database subject headings: Sand filters; California; Performance; Costs; Maintenance.

Both the driving response and static bearing capacity of open-ended piles are affected by the soil plug that forms inside the pile during pile driving. In order to investigate the effect of the soil plug on the static and dynamic response of an open-ended pile and the load capacity of pipe piles in general, field pile load tests were performed on instrumented open- and closed-ended piles driven into sand. For the open-ended pile, the soil plug length was continuously measured during pile driving, allowing calculation of the incremental filling ratio for the pile. The cumulative hammer blow count for the open-ended pile was 16% lower than for the closed-ended pile. The limit unit shaft resistance and the limit unit base resistance of the open-ended pile were 51 and 32% lower than the corresponding values for the closed-ended pile. It was also observed, for the open-ended pile, that the unit soil plug resistance was only about 28% of the unit annulus resistance, and that the average unit frictional resistance between the soil plug and the inner surface of the open-ended pile was 36% higher than its unit outside shaft resistance. DOI: 10.1061/(ASCE)1090-0241(2003)129:4(296) CE Database subject headings: Piles driving; Sand; Pipe piles; Static loads; Dynamic loads; Pile load tests.

Gradual downstream fining along gravel-bed rivers is often followed by a relatively abrupt change to a sand bed. This has usually been explained by the breakdown of pebbles of certain lithologies to sand, but it is not restricted to particular rock types and can occur over distances too short for significant abrasion. An alternative explanation is that as shear stress declines downstream, size sorting is enhanced through nonlinearities and thresholds in bedload transport and deposition mechanisms. This hypothesis is tested by numerical modeling of an idealized channel with a mixed gravel and sand bed. Abrupt and persistent gravel fronts with associated breaks of slope develop from a range of smooth initial states when a new initial-motion equation is used, but not with a conventional equation. The results suggest an emergent phenomenon, but one that is sensitive to process specification rather than initial or boundary conditions. Keywords: geomorphology, modeling, gravel front, bedload transport.

We present a transport model for mixed sand/gravel sediments. Fractional transport rates are referenced to the size distribution of the bed surface, rather than subsurface, making the model completely explicit and capable of predicting transient conditions. The model is developed using a new data set of 48 coupled observations of flow, transport, and bed surface grain size using five different sediments. The model incorporates a hiding function that resolves discrepancies observed among earlier hiding functions. The model uses the full size distribution of the bed surface, including sand, and incorporates a nonlinear effect of sand content on gravel transport rate not included in previous models. The model shares some common elements with two previous surface-based transport models, but differs in using the full surface size distribution and in that it is directly developed from a relatively comprehensive data set with unambiguous measurement of surface grain size over a range of flow, transport rate, and sediments. DOI: 10.1061/(ASCE)0733-9429(2003) 129:2(120) CE Database keywords: Sediment transport; Models; Sand; Gravel.

A procedure for estimating the undrained stress-strain behavior of sand from drained self-boring pressuremeter and seismic piezocone penetration tests is proposed in this paper. The procedure offers an inexpensive alternative to laboratory testing and avoids the uncertainty of the empirical methods based on index measurements such as the Standard Penetration Test blow count and the tip resistance in a Piezocone Penetration Test (CPTU). To check its validity, the proposed procedure was used to infer the undrained triaxial stress-strain curves and the results were compared with laboratory triaxial tests on undisturbed samples. The undrained limit equilibrium stability of a dike was also assessed using the inferred stress-strain behavior to illustrate the usefulness of the procedure. The result of the stability analysis was found to be in qualitative agreement with the observed performance of the dike during a recent field experiment attempting to trigger static liquefaction. CE Database keywords: Sand; In situ tests; Stress-strain curves; Dikes; Penetration tests.

While successful in removing turbidity and pathogens from drinking water, slow sand filters require ripening periods at the beginning of each filter run. The premise of this research was that it should be possible to enhance the ripening of slow sand filters. Potential ripening agents were screened by assessing their interaction with the surface of filtration media and turbidity particles. Four natural organic polymers and nine synthetic polymers were investigated for their potential to enhance filter ripening. Of the 13 modifying agents considered, none conclusively sorbed to the filter media, and only one, a synthetic polymer, interacted with kaolin particles. A filter modified with continuous feed of the polymer ripened successfully and produced water with turbidity below 1.0 NTU in about 24 h. Most turbidity removal in the treated filter occurred in the schmutz-decke rather than within the depth of the filter bed. Hence, the mechanism of enhanced ripening in this case probably was particle agglomeration with resulting acceleration of particle deposition at the filter surface accompanied by straining or attachment to previously removed particles.

Model tests were performed at the Geotechnical Centrifuge Facility of Delft University of Technology, The Netherlands, to examine the mechanics of light nonaqueous phase liquid (LNAPL) movement in a partially saturated porous granular medium. The experiment simulated a 2D spill of LNAPL in an unsaturated sand prepared at two values of porosity. The duration of the centrifuge model tests corresponded to a prototype equivalent of 110 days. The choice of modeling a 2D flow together with the use of a transparent container enabled direct visual observation of the experiments. Scaling laws developed in connection with other centrifuge modeling studies were used to support the test results. Tests were conducted at two different centrifuge accelerations to verify, by means of the 'modeling of models technique,' the similitude between the different experiments. The paper presents details of the experimental methodologies and the measuring techniques used to evaluate the final distribution of water and LNAPL content in the soils.

This study presents direct evidence for the influence of the previbration cycles induced in the conventional resonant colum tests on the measured dynamic properties of a dry sand. The tests were performed on an energy-injecting virtual-mass resonant column system, under which the material properties can be measured at a very low number of previbration cycles (

The coupled bridge foundation-superstructure finite-element code FLPIER was employed to predict the lateral response of the single piles and 3 x 3 to 7 x 3 pile groups founded in both loose and medium dense sands. The p-multiplier factors suggested by McVay et al. for laterally loaded pile groups with multiple pile rows were implemented for the predictions. The soil parameters were obtained through a back-analysis procedure based on single pile test results. The latter, as well as the numerical predictions of both the single and group tests, are presented. It was found that the numerical code FLPIER did an excellent job of predicting the response of both the single piles and the 3 x 3 to 7 x 3 pile groups. The latter involved the predictions of lateral load versus lateral deflection of the group, the shears and bending moments developed in the individual piles, and the distributions of the lateral loads in each pile row, which were all in good agreement with the measured results.

The ultimate bearing capacity of short, precast concrete piles driven into calcareous sands was examined by pile-load tests carried out at two sites in Kuwait. The piles had a 0.3 m x 0.3 m square cross section and extended to a maximum depth of 12 m. They were driven through a loose-to-compact calcareous surface sand layer underlain by a competent dense-to-very-dense siliceous cemented sand deposit. The pile tips and part of the pile shafts were embedded in the lower layer. The base resistance and shaft friction were calculated using the Meyerhof method for a layered soil profile. The method employs the standard penetration test N values. The results indicate that a great portion of the pile capacity is due to base resistance. The skin friction mobilized is small and consists of two components corresponding to the two layers penetrated along the pile shafts. The calculated pile capacities were very close to the measured values. The unit skin friction is not constant along the pile shafts.

Factors affecting the strength, modulus, stress-strain, and time-to-failure relationships of moist-cured silicate-grouted sands were investigated from short-term and creep tests. Variables included in the short-term tests were curing time, sand gradation and mineralogy, rate of loading, curing time, and confining pressure. Confining pressure was varied up to 550 kPa, and the stress and strain loading rates were varied from 0.05 to 5.0 Pa/min and from 0.01 to 1.0%/min, respectively. The shear strength and failure strain of moist-cured grouted sands were independent of the confining pressure, but they were affected by all other variables investigated. Compressive failure strains for silicate-grouted sands were less than 0.4% and the limitation in improving the compressive strength of sand has been quantified. Grouted limestone sand had the highest strength. The creep behavior of grouted sand was also investigated. Stress-strain and time-to-failure relationships for grouted sands have been developed.

A 1D saturated sand layer of 2 m in thickness, in which a silt seam is sandwiched, is liquefied by an instant shock. It is found that a water film is easily formed beneath the silt seam with a thickness as thin as a few millimeters just after liquefaction in loose sand and that the film lasts longer than the post-liquefaction settlement. The effect of the water film on pore-pressure distribution and sand settlement is intensively studied. 1g shake table tests are then carried out for 2D models with or without seams of silt within a saturated sand layer. In the former case, water films formed beneath silt seams just after liquefaction enable the soil mass above them to glide due to an unbalanced force along the water films, not only during but also after shaking. In the latter case, the soil deforms continuously, mostly during shaking, and stops afterward. Thus, a significant effect of water films formed beneath thin, low-permeability sublayers in a liquefied loose sand, on the failure mode and timing in lateral spread, is clearly demonstrated by these simple model tests.

A general approach has been established to assess the undrained stress-strain curve and effective stress path under monotonic loading from drained triaxial tests. An appropriate formulation of a drained and drained rebounded (i.e., over-consolidated) triaxial test response is developed that, in turn, allows the assessment of developing liquefaction and the undrained behavior of saturated sands. The formulation presented is based upon reported experimental drained test results that were obtained from different investigators using different testing techniques. This formulation is a function of the confining pressure and basic properties of the sand, such as relative density, uniformity coefficient, and particle shape (roundness), which can be obtained from visual inspection. The approach is verified by comparing predicted and reported (observed) undrained behavior. The developed formulas allow one to predict the potential of sand to liquefy, the type of liquefaction, the peak and residual strength values, as well as the whole undrained stress-strain curve and effective stress path. The simplicity of this approach makes it an attractive general method to characterize the undrained behavior of sands in a preliminary analysis with no need to run sophisticated experimental tests.

Sand is found all over the earth, including under the sea, and clouds have been dated by painters.

The potential for changes in the wettability of a subsurface system following exposure of sands to a variety of non-aqueous-phase liquids (NAPLs) was assessed. Many of the NAPLs were collected from field sites with on-going NAPL recovery systems. Three methods were used to evaluate the wetting conditions: contact angle measurements, a qualitative bottle test, and capillary pressure-saturation curves. The results clearly show that a wide range of wetting conditions can be expected following spills of complex NAPL mixtures to the subsurface. NAPLs comprised of higher molecular weight constituents - such as creosote - or with added surfactants - such as gasoline - had a greater impact on the system wettability than the lower molecular weight NAPLs. Neat solvents did not have a significant impact on the wettability of quartz surfaces. Many of the petroleum products tested resulted in the formation of weakly water-wet surfaces. Under these conditions, the potential recovery of NAPL from the subsurface would be maximized. Much lower recoveries would be expected for the NAPL-wetting creosote and coal tar contaminants, however.

The surface activity of the isopod Tylos europaeus is dependent on the air humidity and temperature, and wind direction. The isopod, present in a sandy beach in Burano, Italy, is mainly nocturnal and is active during autumn and summer. T. europaeus is present in the eulittoral with the juveniles nearer to the sea and the adults further away from the sea. The hourly zonation of individuals is affected by the sand temperature. The zonation of T. europaeus buried in the sand depends on the mean grain size, moisture and oxygen content of the sand.

Research has been conducted on Escherichia coli concentrations and interactions in sand and beach water in Lake Michigan. The hypothesis that E. coli concentrations in sand control beach water quality has been tested and discussed.

This paper presents the soil friction restraint on oblique pipelines in loose sand. A series of experimental tests are conducted in a prefabricated large-scale drag box with dimensions 1.83 m x 1.83 m x 1.22 m. Model pipes 0.61 m long with diameters of 152.4, 228.6, and 304.8 mm are obliquely moved from an axial-longitudinal to lateral-transversal direction in the drag box to study the associated soil restraints of the oblique pipes with various shallow embedded depths. All the test results indicate that for the axial pipes, the longitudinal soil restraint could be estimated as the product of the average of the vertical and horizontal earth pressures at the centerline of the pipe and the tangent value of soil-pipe friction angle, whereas for the lateral pipes, the transversal soil restraint could be predicted by using the limit equilibrium model with the assumption of the planar sliding failure surface. The longitudinal and transversal soil restraints of the oblique pipes could geometrically be obtained by multiplying the corresponding cosine and sine values of the oblique angle with the associated longitudinal soil restraint of axial pipe and the transversal soil restraint of the lateral pipe, respectively. The findings also indicate that the scale effects are not significant for the size of the pipes tested herein.

A recommendation is made to base grouted sand behavior analysis on both partial and total filling of pores to study particulate as well as continuum behavior. Continuum behavior, however, is posited to be optimum for peak stress analysis.

A new research related to wind whipped migration of tiny grains of sand which are held back due generation of electric fields from friction between grains is reported. This process called as saltation could provide better understanding of underlying climate change.