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In this study, new empirical predictive relationships for earthquake-induced crest settlement of earth-core rockfill dams (ECRDs) were developed. A case history database of 19 dams that had been subjected to earthquakes was utilized. The presented relationships correlate the intensity measure (IM) of the earthquake records with the observed settlements, and thus, employing IMs that appropriately describe the severity of ground motion is of vital importance. It is well known that the dynamic properties of an ECRD can change significantly depending on the severity of an earthquake, and that this phenomenon can substantially impact the dynamic responses of dams. Accordingly, two IMs were suggested, taking into account the essential characteristics of ground motions affecting the nonlinear behaviour of ECRDs. The results indicate that the proposed relationships effectively address the limitations of the existing ones, and that they are practical tools that efficiently predict the seismic settlements of ECRDs. Key words: ECRD, rockfill dams, crest settlement, earthquake, 1. Introduction Earth-core rockfill dams (ECRDs) are being constructed more and more across the globe. One seismic safety concern for ECRDs (i.e., cases with no liquefaction potential) involves excessive permanent [...]

A framework for thaw consolidation of fine-grained soils is proposed. The development of the framework is based on the general definition of large-strain consolidation and on the general behaviour of soils upon thawing. The residual stress and the residual stress curve are used in the framework to define the initial thawed state. The concept of the residual stress is generalized to ice-rich soils by specifying that the residual stress is the effective stress within the soil elements upon thawing rather than the effective stress in the bulk soil. The framework is formulated in terms of σ v ′ - e - k v relationships. The volume change behaviour of ice-poor soils is described by a semi-logarithmic linear σ v ′ - e relationship. The slope of the log ⁡ σ v ′ - e relationship is given by the compression index of the thawed soil. For ice-rich soils, a bilinear log ⁡ σ v ′ - e relationship is adopted. First, drainage of the excess water occurs with no compression of the soil skeleton. Then, water is drained out of the soil upon compression of the soil skeleton in an ice-poor equivalent manner. The e−kv relationship of thawed fine-grained soils is defined by a semi-logarithmic linear curve with a slope defined by the hydraulic conductivity change index of the thawed soil. [ABSTRACT FROM AUTHOR]

In this study, the thaw consolidation properties of fine-grained permafrost soils are investigated in terms of the characteristics of the relationships between the effective stress (σv′), the void ratio (e), and the hydraulic conductivity (kv). A total of 182 individual soil samples are included in the analysis covering a wide range of hydromechanical properties. The data are obtained from geotechnical studies undertaken for the Canadian Arctic Gas Pipeline project in the 1970s in the Mackenzie River Valley, Canada. The investigated characteristics are defined in agreement with the definition formulated by previous thaw consolidation models for fine-grained soils. Based on the general interpretation of the behavior of thawing soils, relationships are developed for the compression index of the thawed soil, the residual stress, the hydraulic conductivity change index of the thawed soil, and the initial hydraulic conductivity of the thawed soil. All properties are influenced by the ice content, which is characterized by the initial thawed void ratio for ice-rich soils and by the thawed void ratio for ice-poor soils. The liquid limit, the clay content, and the median grain size of the fine fraction are used as predictive parameters in combination with the initial ice content. The median grain size of the fine fraction yields the lowest error for the prediction of the characteristics of the σv′−e−kv relationships. [ABSTRACT FROM AUTHOR]

In this study, the effect of concrete face slab--cushion layer interface behavior on the performance of face slabs in concrete-faced rockfill dams (CFRDs) is investigated using the finite element method. The body of the CFRD is simulated by the cap elastoplasticity model while the interface zone between the concrete face slab and the gravelly cushion layer is simulated explicitly by an advanced interface constitutive model, developed in the framework of critical state soil mechanics and state parameters, and capable of simulating volumetric behavior and stress path dependency. The effect of elastic and elastoplastic material behavior and water level on the stress and displacement responses of the concrete face slab is examined, and the influence of the roughness at the interface area between the concrete face slab at the contact face and the cushion layer on the performance of the concrete face slab is investigated. Comparison of the results with and without the explicit consideration of the interface behavior shows the importance of incorporating advanced constitutive interface modeling in the design and analysis of CFRDs. Key words: concrete face rockfill dam, advanced interface constitutive model, soil-structure interaction, critical state soil mechanics, interface roughness. Dans cette etude, nous enquetons sur l'effet de l'interface entre la dalle en beton et la couche coussinee sur la performance des dalles de facade dans les barrages en enrochements en beton (CFRDs). Pour ce faire, nous avons recours a la methode des elements finis. Le corps du CFRD est simule par le biais du modele d'elastoplasticite du bouchon tandis que la zone d'interface entre la dalle en beton et la couche coussinee graveleuse est explicitement simulee au moyen d'un modele constitutif d'interface avancee, developpee dans le cadre de la mecanique des sols critiques et des parametres d'etat, capables egalement de simuler le comportement volumetrique et la dependance au chemin de contrainte. L'effet du comportement du materiau elastique et elastoplastique et du niveau d'eau sur les reponses de contrainte et de deplacement de la dalle en beton est examine. Par ailleurs, l'influence de la rugosite sur la surface d'interface entre la dalle en beton et la couche de contact sur la performance de la dalle de facade est etudiee. La comparaison des resultats prenant en compte et sans prendre en compte l'explicite du comportement de l'interface montre l'importance d'incorporer la modelisation d'interface constitutive avancee dans la conception et l'analyse des CFRDs. [Traduit par la Redaction] Mots-cles : barrage en enrochements en beton, modele constitutif d'interface avance, interaction sol-structure, mecanique des sols a l'etat critique, rugosite de l'interface., 1. Introduction Rock-fill dam construction has been carried out since the 18th century. A particular type that has been used with increasing frequency in recent decades is the concrete-faced rockfill [...]

A simple, yet complete framework is introduced with the aim or modelling gram breakage in sous and crusnabie granular materials. The evolution of grain breakage is measured using a specific parameter of the grain-size distribution. The evolution of this new breakage parameter is related to the applied mechanical work, which allows the predictions to be independent of the stress paths. The correlation function proposed is trilinear, and is capable of describing the initiation, development, and stabilization of breakage. The initial state, coupled with three additional parameters, is used to calibrate this function. The three parameters are related to a grain specific quantity representing the strength of the particles that form the granular medium. The theory of fractal fragmentation is adopted, and the final state is considered to be unique and described by a single parameter: the fractal dimension. When tested against experimental results, this model was able to correctly predict the crushable behavior of a sand. Key words: particle breakage, granular media, grain crushing, fractal, particle strength, grain size distribution. Un cadre mecanique a la fois simple et complet est introduit dans le but de modeliser la rupture des grains dans les sols et autres milieux granulaires broyables. L'evolution de la rupture des grains est mesuree en utilisant un parametre caracteristique de la distribution granulometrique. L'evolution de ce nouveau parametre de rupture est reliee au travail mecanique applique, ce qui rend les predictions independantes du chemin des contraintes. La fonction de correlation proposee est trilineaire, et donc capable de decrire l'initiation, le developpement et la stabilisation de la rupture. L'etat initialainsi que trois autres parametres servent a calibrer cette fonction. Les trois parametres sont relies a une quantite propre au grain, et qui represente la resistance des particules qui forment le milieu granulaire. La theorie de la fragmentation fractale est adoptee, et l'etat final est donc suppose comme etant unique, et decrit par un seul parametre : la dimension fractale. Lorsque le modele est teste et les resultats compares a des travaux experimentaux, il devient possible d'apprecier la capacite du modele a simuler le comportement d'un sable. Mots-cles: rupture des particules, milieu granulaire, broyage des grains, fractal, resistance des particules, distribution granulometrique., Introduction Granular materials are of particular interest for civil engineers and soil mechanics specialists. Over time, the integrity of these materials varies depending on the mechanical conditions, the nature of [...]

A one-dimensional model for the consolidation of thawing soils is formulated in terms of large-strain consolidation and heat-transfer equations. The model integrates heat transfer due to conduction, phase change, and advection. The hdromechanical behaviour is modelled by large-strain consolidation theory. The equations are coupled in a moving boundary scheme developed in Lagrangian coordinates. Finite strains are allowed and nonlinear effective stress--void ratio--hydraulic conductivity relationships are proposed to characterize the thawing soil properties. Initial conditions and boundary conditions are presented with special consideration for the moving boundary condition at the thaw front developed in terms of large-strain consolidation. The proposed model is applied and compared with small -strain thaw consolidation theory in a theoretical working example of a thawing fine-grained soil sample. The modelling results are presented in terms of temperature, thaw penetration, settlements, void ratio, and excess pore-water pressures. Key words: thaw consolidation, permafrost, thaw settlement, thawing soil. Un modele unidimensionnel de consolidation au degel est formule en combinant les theories de consolidation a grandes deformations et de transfert de chaleur. Le modele inclut les transferts de chaleur dus a la conduction, au changement de phase et a l'advection. Le comportement hydromecanique est modelise selon la theorie de consolidation a grandes deformations. Les equations sont couplees dans un systeme a frontieres mobiles developpe en coordonnees lagrangiennes. Les deformations finies sont permises et l'evolution des proprietes du sol est caracterisee par des relations contrainte effective--indice des vides--conductivite hydraulique non lineaires. Les conditions initiales et les conditions limites sont presentees avec une attention particuliere portee au developpement des conditions limites mobiles au front de degel en fonction de la consolidation a grandes deformations. Le modele propose est applique et compare a la theorie de consolidation au degel a petites deformations dans un exemple theorique du degel d'un echantillon de sol a grains fins. Les resultats de modelisation sont presentes en fonction de la temperature, de la penetration du degel, du tassement, de l'indice des vides et des pressions interstitielles excedentaires. Mots-cles: consolidation au degel, pergelisol, tassement au degel, degel du sol., Introduction The assessment of instabilities related to thawing soils is paramount for the sustainable design of infrastructure built on permafrost. There is thus a substantial incentive for developing a comprehensive [...]

In this study, employing a database of 19 concrete face rockfill dam (CFRD) cases, two prediction methods for post-construction settlement of CFRDs are presented. In the first method, post-construction settlements are estimated using height of the embankment. In the second method, characterization of the stress--strain behavior of the compacted rockfill layers during construction allows prediction of the subsequent stress--strain--time behavior of the embankment. Knowledge of rock particles strength is necessary in both methods. In the presented methods, settlements are estimated separately for each of the three life-cycle phases: before, during, and after impoundment. The presented results show that, in addition to addressing some limitations of previous methods, the proposed approach is precise and highly practical. It also allows a better understanding of rockfill deformation mechanisms. Apart from using this method for predictive purposes, the presented graphs can be used to distinguish unexpected settlement behavior of a CFRD during its post-construction lifespan. Key words: concrete face rockfill dam (CFRD), rockfill, time-dependent, post-construction, settlement, prediction. Dans cette etude, a partir d'une base de donnees de 19 barrages en enrochement avec un masque amont en beton (<< CFRD >>), deux methodes de prediction de tassement post-construction de CFRDs sont presentees. Dans la premiere methode, les tassements post-construction sont estimes en fonction de la hauteur du remblai. Dans la deuxieme methode, le comportement contrainte-deformation de l'enrochement des remblais lors de la construction permet de predire le comportement contrainte-deformation-temps subsequent du barrage. La connaissance de la resistance des particules rocheuses est necessaire avec les deux methodes. Pour ces deux methodes, les tassements en crete sont estimes separement pour chacune des trois phases du cycle de vie d'un barrage : avant, pendant et apres la mise en eau du reservoir. Les resultats presentes montrent qu'en plus de surmonter les difficultes reliees aux methodes actuelles, les approches proposees sont precises et tres pratiques. Elles permettent, egalement, une meilleure comprehension des mecanismes de deformation de l'enrochement. En plus de servir d'outil predictif des tassements, les relations presentees peuvent etre utilisees afin de detecter un comportement atypique d'un CFRD au cours de sa duree de vie. Mots-cles: barrage en enrochement avec masque amont en beton (CFRD), enrochement, en fonction du temps, post-construction, tassement, prediction., Introduction The origin of rockfill dams can be traced back to the mining region of California Sierras, in the 1850s. Rockfill dams were of the impervious face type, constructed by [...]

A number of investigations have shown that the shear strength of unsaturated soils can be defined in terms of effective stress. The difficulty in this approach lies in quantifying the effective stress parameter, or Bishop's parameter. Although often set equal to the degree of saturation, it has recently been suggested that the effective stress parameter should be related to an effective degree of saturation, which defines the fraction of water that contributes to soil strength. A problematic element in this approach resides in differentiating the water that contributes to soil strength from that which does not contribute to soil strength. To address this difficulty, the paper uses theoretical considerations and experimental observations to partition the water retention function into capillary and adsorptive components. Given that the thin liquid films of adsorbed water should not contribute to effective stress, the effective stress parameter is solely related to the capillary component of water retention. In sample calculations, this alternative effective stress parameter provided very good agreement with experimental data of shear strength for a variety of soil types. Key words: shear strength, suction, partial saturation, effective stress, constitutive relations. Maintes etudes ont demontre que la resistance au cisaillement des sols non satures peut etre definie en termes de contrainte effective. La difficulte de cette approche reside dans la determination du parametre de contrainte effective, ou parametre de Bishop. Bien qu'il soit souvent considere egal au degre de saturation, certaines etudes recentes considerent que le parametre de contrainte effective devrait etre relie a un degre de saturation effectif, qui definit la fraction d'eau contribuant a la resistance du sol. Il s'avere toutefois difficile de differencier la fraction d'eau qui contribue a la resistance de celle ne contribuant pas a la resistance. Afin de surmonter cette difficulte, cet article utilise des considerations theoriques et des observations empiriques afin de separer la fonction de retention d'eau en composantes capillaire et d'adsorption. Le parametre de contrainte effective est alors uniquement relie a la composante capillaire de la fonction de retention d'eau, car l'eau adsorbee a la surface des particules solides ne devrait pas contribuer a la resistance du sol. L'analyse de nombreux resultats demontre que cette definition du parametre de contrainte effective procure un tres bon accord entre les observations et les predictions de la resistance au cisaillement d'une variete de types de sols. Mots-cles : resistance au cisaillement, succion, saturation partielle, contrainte effective, relations constitutives., Introduction Shear strength is a fundamental material property that is required to address a variety of engineering problems ranging from slope stability to bearing capacity. In recent years, a number [...]

The authors wish to thank the discussers for their interest and comments on our recent paper (Konrad and Lebeau 2015). The definition of shear strength in unsaturated soils is unquestionably [...]

The thermal conductivity of bitumen concrete is a key parameter in the thermal analysis of pavements submitted to widely varying climate conditions. This paper presents the experimental results of thermal conductivity of bitumen concrete typically used in the Province of Quebec. The results show that the thermal conductivity of bitumen concrete is dependent on the aggregate's mineral origin and on the amount of air voids. It is also shown that the presence of bitumen increases thermal conductivity compared to unbound aggregates. The paper demonstrates that the effect of bitumen creates thermal bridges between aggregate particles similarly to other types of binders such as Portland cement and natural binders found in sedimentary rocks. Based on these observations and on the analyses of over 80 data sets from the literature, an existing model is used to develop a simplified thermal conductivity equation to estimate this parameter for bitumen concrete. Key words: pavements, thermal conductivity, bitumen concrete, aggregates, air voids, density, thermal conductivity model. La conductivite thermique du beton bitumineux est un parametre cle des analyses thermiques des chaussees soumises a des conditions climatiques tres changeantes. Cet article presente les resultats experimentaux de la conductivite thermique du beton bitumineux normalement utilisee dans la Province de Quebec. Les resultats montrent que la conductivite thermique du beton bitumineux depend de la mineralogie des agregats et de la quantite de vides inter-granulaires. Il est egalement montre que la presence de bitume augmente la conductivite thermique par rapport a des agregats non lies. Cet article demontre que le bitume cree des ponts thermiques entre les particules d'agregat, semblables a ce que font d'autres types de liants, tels que le ciment Portland ou les liants naturels retrouves dans les roches sedimentaires. En se basant sur ces observations et sur les analyses de plus de 80 ensembles de donnees tires de la litterature, un modele existant est utilise afin de developper une equation simplifiee d'estimation de la conductivite thermique du beton bitumineux. [Traduit par la Redaction] Mots-cles: chaussees, conductivite thermique, beton asphaltique, agregats, vides inter-granulaires, densite, modele de conductivite thermique., Introduction The temperature at the pavement surface influences the mechanical performance of road structure, frost action in subgrade soils, and winter maintenance operation. In the last three decades, heat transfer [...]

An optical sensor was designed to measure the fine solid particles concentration contained in a fluid flow. This sensor is composed of four light-emitting diodes and four associated light-dependent resistors, allowing the measurement of fluid transparency. Given the small device dimensions, it can be placed close to the particles exit from the specimen. The optical sensor is able to instantaneously measure a large range of clay or silt concentrations in the effluent, without a significant influence of flow rate. The presence of sand grains in fluid flow can be detected. The use of this sensor with a specific triaxial device allows precise characterization of the initiation and development of the suffusion process on clayey sand specimens. It is shown that suffusion of clay particles induces a decrease of hydraulic conductivity, which is due to a diffuse process of eroded particles filtration. Clay suffusion and filtration processes are influenced by grain-size distribution and also by grain shape of the coarse fraction. Under a high hydraulic gradient, clay suffusion can be accompanied by sand erosion. The critical value of mean pore velocity to initiate clay suffusion was determined for the types of soils. Key words: laboratory testing, seepage, transparency, solid particle concentration, suffusion, pore velocity. Un capteur optique a ete concu pour mesurer la concentration en particules fines d'un ecoulement de fluide. Ce capteur est compose de quatre diodes emettrices de lumiere, et de quatre photo resistances associees qui mesurent la transparence du fluide. Puisque l'appareil est de faible dimension, il peut etre place pres de l'endroit ou les particules sortent de l'echantillon. Le capteur optique peut mesurer instantanement une large gamme de concentrations d'argile ou de limon dans l'effluent sans influence significative du taux d'ecoulement. La presence de grains de sable dans l'ecoulement peut etre detectee. L'utilisation de ce capteur avec un appareil triaxial specifique permet de caracteriser precisement l'initiation et le developpement du processus de suffusion sur des echantillons de sable argileux. Il est demontre que la suffusion des particules argileuses induit une diminution de la conductivite hydraulique en raison d'un processus diffus de filtration des particules erodees. La suffusion de l'argile et le processus de filtration sont influences par la granulometrie et aussi par la forme de la fraction grossiere. Sous un gradient hydraulique eleve, la suffusion de l'argile peut etre accompagnee par l'erosion du sable. La valeur critique de la vitesse moyenne dans les pores pour initier la suffusion de l'argile a ete determinee pour les types de sol. Mots-cles : essais en laboratoire, ecoulement, transparence, concentration en particules solides, suffusion, vitesse dans les pores. [Traduit par la Redaction], Introduction Detection of the initiation of solid particle transport in compacted soils subjected to seepage and determination of solid particle concentration in fluid flow are important, notably in the field [...]

Air convection within coarse rock-fills enhances winter-time heat extraction from underlying soils. Modeling this phenomenon requires the knowledge of intrinsic permeability. This study focuses on the measurement of intrinsic permeability using natural air convection within a 1 [m.sup.3] test cell. Upward heat flow conditions are applied to various specimens. Test results are analyzed using a theoretical solution of natural convection in a square enclosure. Four materials were studied, with effective particle sizes ([d.sub.10]) ranging from 90 to 150 mm and porosities ranging from 0.37 to 0.41. The results showed that intrinsic permeability increases with increasing [d.sub.10]. The experimental results were adequately predicted by the Kozeny-Carman and Chapuis equations. Only slight deviations were observed, which is considered acceptable given that these equations were developed for materials with much smaller values of [d.sub.10]. The experimental results of this study confirm the value of intrinsic permeability recently used in a study of natural convection within a rock-fill dam in northern Quebec, Canada. Key words: natural convection, intrinsic permeability, effective particle size, porosity, rock-fill materials. La convection de l'air a l'interieur de remblais rocheux faits de materiaux grossiers augmente la perte de chaleur en hiver des sols sous-jacents. La modelisation de ce phenomene necessite de connaitre la permeabilite intrinseque. Cette etude se penche sur la mesure de la permeabilite intrinseque a partir de la convection naturelle de l'air a l'interieur d'une cellule d'essai 1 [m.sup.3]. Des conditions d'ecoulement de chaleur vers le haut sont appliquees a differents echantillons. Les resultats sont analyses a l'aide d'une solution theorique de la convection naturelle dans un espace ferme et carre. Quatre materiaux ont ete etudies; ces materiaux ont des tailles de particules effectives ([d.sub.10]) variant entre 90 et 150 mm, et des porosites variant entre 0,37 et 0,41. Les resultats demontrent que la permeabilite intrinseque augmente lorsque [d.sub.10] augmente. Les resultats experimentaux ont ete predits de facon adequate par les equations de Kozeny-Carman et de Chapuis. De legeres deviations ont ete observees, ce qui est considere acceptable puisque ces equations ont ete developpees pour des materiaux ayant des valeurs de [d.sub.10] beaucoup plus faibles. Les resultats experimentaux obtenus dans cette etude confirment la valeur de la permeabilite intrinseque utilisee recemment lors de l'etude de la convection naturelle a l'interieur d'un barrage fait de remblai rocheux, situe au nord du Quebec, Canada. Mots-cles: convection naturelle, permeabilite intrinseque, taille des particules effective, porosite, materiaux de remblai rocheux. [Traduit par la Redaction], Introduction Heat transfer in soils is typically governed by conduction (Johansen 1975; Farouki 1981). In some cases, however, processes such as natural convection may significantly contribute to the overall heat [...]

This paper presents an experimental study on thermal radiation and the thermal conductivity of rock-fill materials using a 1 m x 1 m x 1 m heat transfer cell. Testing temperatures are applied by temperature-controlled fluid circulation at the top and bottom of the sample. Heat flux and temperature profiles are measured to establish the effective thermal conductivity [λ.sub.e], which includes contributions from both conduction and radiation heat transfer mechanisms. The materials studied had an equivalent particle size ([d.sub.10]) ranging from 90 to 100 mm and porosity (n) ranging from 0.37 to 0.41. The experimental results showed that thermal radiation greatly affects the effective thermal conductivity of materials with [λ.sub.e] values ranging from 0.71 to 1.02 W x [m.sup.-1] x [K.sup.-1], compared with a typical value of 0.36 W x [m.sup.-1] x [K.sup.-1] for conduction alone. As expected, the effective thermal conductivity increased with particle size. An effective thermal conductivity model has been proposed, and predictions have been successfully compared with the experimental results. Radiation heat transfer becomes significant for [d.sub.10] higher than 10 mm and predominant at values higher than 90 mm. The results of the study also suggest that the cooling potential of convection embankments used to preserve permafrost conditions may not be as efficient as expected because of ignored radiation effects. Key words: radiation, effective thermal conductivity, particle size, porosity, rock-fill materials. Cet article presente une etude experimentale sur la radiation et la conductivite thermique de materiaux de remblai rocheux realisee a l'aide d'une cellule de transfert de chaleur de 1 m x 1 m x 1 m. Les temperatures sont appliquees sur les echantillons par la circulation d'un fluide a temperature controlee au haut et au bas de l'echantillon. Les flux de chaleur et les profils de temperature sont mesures afin d'etablir la conductivite thermique effective [λ.sub.e], qui comprend les deux mecanismes de transfert de chaleur : la conduction et la radiation. Le diametre equivalent des particules ([d.sub.10]) des materiaux etudies varie entre 90 mm et 100 mm, et ils ont une porosite (n) variant de 0,37 a 0,41. Les resultats montrent que la radiation affecte de facon importante la conductivite thermique effective, avec des valeurs de [λ.sub.e] variant de 0,71 a 1,02 W x [m.sup.-1] x [K.sup.-1], comparativement a une valeur typique de 0,36 W x [m.sup.-1] x [K.sup.-1] lorsque seulement la conduction est consideree. La conductivite thermique effective augmente avec la taille des particules. Un modele de conductivite thermique effective est propose, et les predictions correspondent bien aux resultats experimentaux. Le transfert de chaleur par radiation devient significatif lorsque [d.sub.10] est superieur a 10 mm et devient predominant lorsque [d.sub.10] est superieur a 90 mm. Les resultats de cette etude suggerent aussi que [λ.sub.e] potentiel de refroidissement des digues de convection utilisees pour preserver les conditions du pergelisol n'est possiblement pas aussi efficace que prevu puisque les effets de la radiation sont ignores. Mots-cles : radiation, conductivite thermale effective, granulometrie, porosite, enrochement. [Traduit par la Redaction], Introduction The ground thermal regime is generally governed by conduction heat transfer (Johansen 1975). However, in rock-fill embankments made of gravel, cobbles, and boulders, other heat transfer processes may be [...]

Past and current research has clearly established the detrimental effects of inadequate subsurface drainage within a road environment. In response, pavement engineers have developed a number of theoretical models to establish the lateral drainage requirements of pavements. The intention of the present paper is to extend current drainage design by accounting for the presence of a pervious subbase layer. A parametric study of an extended form of the time to drain problem was performed while focusing on the effect of subbase material characteristics under saturated and unsaturated conditions. The numerical results established that the addition of a suitable subbase material can shift drainage time from days to minutes by combining the effects of gravity, seepage distance, and discharge area to enhance vertical water movement. Although increasing saturated hydraulic conductivity of the subbase material was generally shown to favour vertical drainage, it also created a capillary barrier effect that hindered downward flow. The results of this analysis emphasize the importance and relevance of subbase material selection for improving the drainage quality of dense-graded base materials, which display excellent bearing capacity and remain stable under repeated loading. Key words: multilayer pavement systems, highway, drainage, unsaturated, unconfined flow, numerical modelling. Les etudes actuelles et passees ont clairement etabli les effets nefastes du drainage inadequat des structures de chaussees. Pour contrer ces problemes, les ingenieurs ont developpe plusieurs modeles theoriques qui permettent d'etablir les exigences reliees au drainage lateral des structures de chaussees. Cet article presente des travaux ayant pour objectif d'ameliorer la conception du drainage en tenant compte de la presence d'une couche de sous-fondation. Une etude parametrique sur une forme etendue du probleme du temps de drainage a ete effectuee afin d'evaluer l'influence des caracteristiques du materiau de sous-fondation en conditions saturees et non saturees. Les resultats de l'analyse numerique ont demontre que l'ajout d'un materiau de sous-fondation adequat peut changer le temps de drainage de l'ordre des jours a l'ordre des minutes en combinant les effets de la gravite, de la distance de percolation et de la surface d'ecoulement. Malgre que l'augmentation de la conductivite hydraulique saturee du materiau de sous-fondation ameliore generalement l'ecoulement vertical, cette augmentation de la conductivite hydraulique peut engendrer un effet de barriere capillaire nuisible a l'ecoulement de l'eau vers le bas. Les resultats de l'analyse mettent en evidence l'importance et la pertinence de la selection du materiau de sous-fondation pour ameliorer le drainage d'une fondation routiere constituee de materiaux a granulome trie etalee ayant une excellente capacite portante et demeurant stables sous des chargements repetes. Mots-cles : structure de chaussee, autoroute, drainage, non sature, ecoulement non confine, modelisation numerique. [Traduit par la Redaction], Introduction Modern concerns with subsurface drainage within a road environment began with Pierre Marie Jerome Tresaguet (1716-1796) who developed a novel pavement structure in which sloping interfaces were used to [...]

A dynamic analysis based on the spectral element method is described for the interpretation of falling weight deflectometer (FWD) tests on flexible pavements. This dynamic approach was implemented in the computer code Dynamic Analysis of Pavement--Universite Laval (DYNAPAV-UL) that includes both frequency-independent hysteretic damping and frequency-dependent viscous damping material models. A parametric study was conducted on a four-layer flexible pavement to evaluate the influence of different layer moduli on deflection basins and deflection histories. The viscous behaviour of the asphalt concrete layer was also investigated. While the deflection basin currently used in static methods gives some details of the pavement response under transient loading, the simulations of FWD tests using the dynamic model suggest that the time histories should be included as well for the interpretation of FWD deflection measurements. In fact, important dynamic phenomena due to inertial effects and viscous effects are only revealed by deflection histories. Key words: spectral element method, wave propagation, falling weight deflectometer, viscoelasticity, Huet-Sayegh model, flexible pavement. Cet article decrit une methode analyse dynamique basee sur la methode des elements spectraux pour l'interpretation des essais au deflectometre a masse tombante (<< FWD >>) sur des chaussees flexibles. Cette approche dynamique a ete implantee dans le code de calcul Analyse dynamique des chausses - Universite Laval (<< DYNAPAV-UL >>) qui comprend a la fois une loi de comportement visco-elastique avec amortissement hysterese independant de la frequence et un modele materiel d'amortissement visqueux en fonction de la frequence. Une etude parametrique a ete realisee sur une chaussee flexible a quatre couches afin d'evaluer l'influence des differents modules des couches sur les bassin de deflexion et sur les historiques de deflexion. Le comportement visqueux de la couche d'enrobe bitumineux a egalement ete etudie. Bien que le bassin de deflexion actuellement utilise dans les methodes statiques donne certains details de la reponse de la chaussee sous une charge transitoire, les simulations des essais << FWD >> obtenues a l'aide d'une approche dynamique suggerent que les historiques de deflexion soient utilises pour l'interprOtation des mesures de deflexion du deflectometre a masse tombante. En fait, seuls les historiques de deflexion permettent de reveler des phenomenes dynamiques importants causes par les effets d'inertie et les effets visqueux. Mots-cles : methode des elements spectraux, propagation des ondes, deflectometre a masse tombante, viscoelasticite, modele Huet-Sayegh, chaussee flexible. [Traduit par la Redaction], Introduction Pavements are composed of several layers of dense engineered materials placed successively over the subgrade soil. This multilayer structure deteriorates over time under repeated traffic loads. Therefore, nondestructive testing [...]

A robust backcalculation methodology that uses the Levenberg-Marquardt iterative minimization technique is presented to identify the value of unknown layer parameters from falling weight deflectometer (FWD) tests using a dynamic approach based on the spectral element method. Backcalculation is performed in the time-domain with 20 observations on each deflection history. The efficiency of the proposed methodology is demonstrated by interpreting FWD tests on three flexible pavements that cover a variety of structures, soil, and bedrock conditions. Results indicate that the dynamic approach is capable of simulating quite well the measured deflection histories using effective backcalculated moduli. In addition, comparison of critical strains between static and dynamic interpretation of FWD tests indicates that both approaches predict similar traction strains at the bottom of the asphalt concrete layer. However, the prediction of the compression strain in the subgrade with the static approach is erratic compared with the dynamic method. Key words: falling weight deflectometer, pavement, dynamic, backcalculation, effective modulus, deflection histories. Une methode robuste de calcul inverse utilisant la technique iterative de minimisation de Levenberg-Marquardt est presentee dans le but d'identifier la valeur des parametres de couche inconnus des essais realises a l'aide du deflectome tre a masse tombante (<< FWD >>) en utilisant une approche dynamique basee sur la methode des elements spectraux. Le retrocalcul est fait dans le temps a l'aide de 20 observations sur chaque mesure de deflexion. L'efficacite de la methode proposee est demontree en interpretant les essais << FWD >> sur trois chaussees flexibles sans socle rocheux a proximite de la surface. Les resultats indiquent que l'approche dynamique permet de simuler raisonnablement bien les historiques de deflexion mesuree en utilisant des modules retrocalcules effectifs. De plus, la comparaison des deformations critiques entre l'interpretation statique et dynamique des essais << FWD >> indique que les deux approches predisent des deformations de traction similaires a la base de la couche d'enrobe bitumineux. Toutefois, la prevision de la contrainte en compression dans le sol d'infrastructure utilisant l'approche statique est erratique par rapport a celle obtenue par la methode dynamique. Mots-cles : deflectometre a masse tombante, chaussee, dynamique, retrocalcul, module effectif, cas de deflexion. [Traduit par la Redaction], Introduction Under repeated traffic loads and severe climate environment, pavements deteriorate. Structural pavement deficiencies can be detected using nondestructive testing methods such as the falling weight deflectometer (FWD). The FWD [...]

Abstract: Thermal and frost action analyses in soils require the knowledge of the thermal conductivity of soil solid particles. This parameter was obtained using reverse modeling applied to thermal conductivity [...]

Abstract: The presence of an insulating layer in pavement structures generates a cooling effect at the surface. This can lead to slippery conditions on insulated pavement sections, while adjacent conventional [...]

The purpose of this paper is to present macro- and micro-study on the yielding of microstructured geomaterials by numerical experiments. This target is achieved by carrying out 63 one-dimensional and biaxial compressions tests oil an idealized bonded geomaterial with an extension of distinct element method, into which bond contact models proposed were implemented. Numerical results indicate that: (a) preconsolidated pressure appears to attribute to bond and looseness in the geomaterials, and an increase in void ratio leads to a decrease in yielding stress in one-dimensional tests: (b) an increase in bonding strength al interparticle contacts results in an increase in yielding stress and cohesion, and an internal friction angle that is smaller than the critical stale value: (c) the observed first-yielding (initiation of bond breakage) is stress path dependent, and gross-yield (defined with respect to volumetric strain) of microstruclured geomaterials is evidently related to bond breakage. CE Database subject headings: Geomaterials; Yield; Microstructures; Bonding; Numerical models; Discrete elements; Micromechanics.

The forward modeling of the dispersion curve of a layered medium calculated from the spectral characteristics of Rayleigh waves requires an efficient algorithm for predicting the surface displacements of the medium under a dynamic load. The usual methods for solving the wave equation are based on matrix methods prone to numerical problem or yielding to the determination of complex modes that are difficult to interpret. A modified linearized stiffness matrix method is proposed in this technical note to solve the discrete stiffness matrix. The developed algorithm is based oil a finite element equation associating each surface wave mode to the resonant frequency of a structure with a stiffness depending on the wavelength. The filtering of complex wave modes to keep only suitable surface waves is avoided. Furthermore, the mesh design is based oil the actual wavelength of each mode providing a better representation of higher modes. The new algorithm is validated with two irregular stiffness profiles. CE Database subject headings: Stiffness matrix: Dynamic response: Computer aided simulation: Seismic tests: Wave dispersion: Spectral analysis: Layered systems; Surface waves.

The seismic behavior of the concrete slab in concrete-faced rockfill dams (CFRD) is investigated, considering concrete slab-cushion layer interface effect. The interface is simulated by an advanced constitutive model capable of simulating the complex behavior of soil–structure interfaces such as particle breakage, stress-dilatancy, stress-hardening, cyclic accumulative contraction, and stress degradation. Stage construction and reservoir impoundment of the dam are simulated and the dam is subjected to two earthquake records. The concrete slab responses under static and dynamic conditions are examined, and the effects of reservoir water level, interface roughness, and the interface modeling approach on the concrete slab response are investigated. [ABSTRACT FROM AUTHOR]

Hydraulic conductivity of thawed consolidated slurries of a silty clay from Lachute, Quebec, Canada, subjected to closed-system freezing at different temperatures ranging from -2 to -12 degrees C were determined from constant-head permeability tests. The permeability index defined as the slope of the relation between log k and void ratio was found to increase with decreasing temperature. It was also established that the ultimate permeability index was related to the temperature at which no further change in unfrozen water content occurs. For the silty clay studied, the permeability index increased from 1.4 for the unfrozen soil prior to freezing to a maximum value of 8 at a temperature of -12 degrees C.

We are grateful for the interest in our paper (Konrad and Salami 2018). The discussers reviewed the conceptual model for particle breakage in granular materials, and proposed ways to improve [...]