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Freeze–thaw cycling is a critical issue in cold-climate engineering because these cycles impact the mechanical properties of soils due to the translocation of water and ice at temperatures near 0 °C. Reinforcement methods have been developed to decrease these adverse effects, including the use of polypropylene (PP) fibers. However, few macrostructural investigations have been able to demonstrate the underlying physical basis for their effectiveness. This study used computed tomography (CT) images of clay samples reinforced with 2% PP fibers and subjected to unconfined compression and Brazilian tests before and after up to 10 closed-system freeze–thaw cycles (FTCs). Significant effects of the FTCs on soil structure include a reduction in macropores and an increase in mesopores. The addition of PP fibers reduces this change in the number of macropores from 28% to 18% following 10 FTCs. Unreinforced samples also show more localized propagation of shear/tensile cracks during tests than reinforced samples as a result of having a higher failure strength and ductility. The bridging effect of fibers, deviation of the failure path, and formation of microcracks around fibers are clearly illustrated in the CT images. This study provides significant insights relevant to engineering design in cold regions. [ABSTRACT FROM AUTHOR]

A design procedure was developed for a relatively unknown slope stabilization technique consisting of a series of parallel sheet piles installed parallel to the direction of slope movement. This technique was introduced in Alberta by R.M. Hardy in the 1970s and is locally referred to as 'Hardy Ribs.' A case study is discussed where Canadian National (CN) Rail installed Hardy Ribs to stabilize a landslide affecting its rail line in western Manitoba. A proposed design procedure is discussed that consists of a de-coupled approach with a separate limit equilibrium slope stability analysis and laterally loaded pile analysis using p-y curves, where p is the soil reaction per unit length and y is the lateral deflection of the pile, to model the soil-pile interaction. Example calculations are provided for the proposed design procedure for the CN case study site to illustrate its use and to estimate the stabilizing effect from the Hardy Ribs at this site. Key words: landslide, slope stabilization, soil-pile interaction, sheet piles, analysis, design procedure. Une procedure de conception a ete developpee pour une technique de stabilisation de pentes relativement inconnue consistant en une serie de palplanches paralleles installees parallelement a la direction du mouvement de la pente. Cette technique a ete introduite en Alberta par R.M. Hardy dans les annees 1970 et est localement appelee << Hardy Ribs >>. Une etude de cas est analysee ou Canadien National (CN) Rail a installe des Hardy Ribs pour stabiliser un glissement de terrain affectant sa ligne de chemin de fer dans l'ouest du Manitoba. On considere une procedure de conception proposee qui consiste en une approche decouplee avec une analyse de stabilite de pente d'equilibre limite separee et une analyse de pieu charge lateralement utilisant des courbes p-y pour modeliser l'interaction sol-pieu. Des exemples de calculs sont fournis pour la procedure de conception proposee pour le site de l'etude de cas CN afin d'illustrer son utilisation et d'estimer l'effet stabilisateur des Hardy Ribs sur ce site. [Traduit par la Redaction] Mots-cles: glissement de terrain, stabilisation de pentes, interaction sol-pieu, palplanches, analyse, procedure de conception., Introduction Cast-in-place concrete piles and driven steel piles have been used in many cases to stabilize slow moving landslides in Alberta (Abdelaziz et al. 2011). An alternative pile type that [...]

Rail tracks on peat subgrades can experience significant deflections, some of which have led to derailments. A potential ground stabilization strategy is to use screw piles to reduce rail displacements; however, limited research has been undertaken to investigate the effect of these piles and their performance under cyclic train loading. A field site was instrumented and monitored before and after screw pile installation. The piles were instrumented with strain gauges, piezometers were installed in the peat, and high-speed cameras were used to measure track and subgrade displacements. The load carried by each instrumented pile was approximately 50-60 kN 3 weeks after installation, but reduced to approximately 30 kN after 6 months. Although 1 year's worth of piezometric data were collected before installation of the piles, it is difficult to conclusively attribute the changes in pore pressures to the piles, particularly because the piezometric data collected after the pile installation were only available for the 7 months that exhibit the period of greatest seasonal fluctuations. The track support system deformations showed no significant difference pre- and post-pile installation. Therefore, based on the monitoring data at this site, it appears that the designed transfer of load from the ties to the piles through arching within the ballast layer was not realized.Key words: helical screw piles, rail track, rehabilitation, monitoring, sensors.Les voies ferrees sur des plate-formes de tourbe peuvent subir des deformations importantes, certaines qui ont entraine des deraillements. Une strategie potentielle de stabilisation du sol consiste a utiliser des pieux visses pour reduire les deplacements de rails. Cependant, peu de recherches ont ete entreprises pour etudier l'effet de ces pieux et leur performance sous chargement cyclique des trains. Un site de terrain a ete instrumente et surveille avant et apres l'installation de pieux visses. Les pieux ont ete instrumentes avec des jauges de contrainte, des piezometres ont ete installes dans la tourbe, et des appareils pour photographie ultra-rapide ont ete utilises pour mesurer les deplacements de la voie et de la plate-forme. La charge portee par chaque pieu instrumente etait d'environ 50 a 60 kN 3 semaines apres l'installation, mais reduite a environ 30 kN apres 6 mois. Bien qu'une annee de donnees piezometriques ait ete collectee avant l'installation des pieux, il est difficile d'attribuer de maniere concluante les changements de pression interstitielle aux pieux, en particulier parce que les donnees piezometriques recueillies apres l'installation des pieux n'etaient disponibles que pour les 7 mois qui presentent la periode des plus grandes fluctuations saisonnieres. Les deformations du systeme de support de la voie n'ont montre aucune difference significative entre la periode avant et apres l'installation des pieux. Par consequent, d'apres les donnees de surveillance sur ce site, il semble que le transfert concu de la charge des traverses aux pieux par l'arquage a l'interieur de la couche de ballast n'a pas ete realise. [Traduit par la Redaction]Mots-cles : pieux visses helicoidaux, voie ferree, rehabilitation, surveillance, capteurs., IntroductionSections of track over muskeg often have high deflections beneath train loading (Hendry et al. 2010, 2013). These conditions have been shown to be the primary cause of an increased [...]

The use of pore pressure responses to fluctuations in total stress (resulting from barometric pressure changes) to calculate moduli and other material properties is a recently developed technique being applied to deep aquitard formations. Initially, the method has relied on visual interpretation of the data from grouted-in piezometers, resulting in a qualitative result with little opportunity to define the quality of measured data; more recently, linear and multiple regression analyses were used to assess the same properties with limited success. Here, a methodology is developed to determine loading efficiency from pore pressure measurements using filtering and numerical regression. The results indicate a near linear relationship between the change in pore pressure and change in stress (barometric pressure), resulting in an estimation of loading efficiency and quantification of the quality of fit. Four to 6 days of data appear to best isolate the barometric fluctuation with the developed filters. The technique is successfully applied to a 'simple' site, where groundwater conditions are relatively stable, as well as a complex site, where groundwater conditions are changing due to fluctuating river levels. The successful application to the latter site shows that robust analysis is possible, even for dynamic and complex environments, and that the method represents a viable alternative for estimating material parameters of formations that are historically difficult to characterize. Key words: barometric efficiency, modulus, pore pressures, small strain. L'utilisation des reponses de la pression interstitielle aux fluctuations en stress total (suite aux changements de pression barometrique) pour calculer les modules et autres proprietes materielles est une technique recemment developpee appliquee aux formations profondes d'aquitard. A l'origine, la methode etait basee sur une interpretation visuelle des donnees des piezometres encastres, donnant lieu a un resultat qualitatif offrant peu de possibilites de definir la qualite des donnees mesurees; plus recemment, l'analyse lineaire et a regression multiple a ete utilisee pour evaluer les memes proprietes avec un succes limite. Ici, une methodologie est developpee pour determiner l'efficacite de chargement a partir des mesures de pression interstitielle par une filtration et une regression numerique. Les resultats indiquent une relation presque lineaire entre le changement de la pression interstitielle et le changement dans le stress (pression barometrique), donnant lieu a une estimation de l'efficacite de chargement et a la quantification de la qualite de l'adaptation. Quatre a 6 jours de donnees semblent etre preferables pour isoler la fluctuation barometrique avec les filtres developpes. La technique est appliquee avec succes a un site 'simple', ou les conditions de nappe aquifere sont relativement stables, ainsi qu'a un site complexe, ou les conditions de nappe aquifere changent en fonction de la variation des niveaux des rivieres. Cette application reussie a ce site montre qu'une analyse solide est possible, meme dans des environnements dynamiques et complexes, et que la methode represente une alternative viable afin d'estimer les parametres materiels des formations historiquement difficiles a caracteriser. [Traduit par la Redaction] Mots-cles : efficacite barometrique, module, pressions interstitielles, faible deformation., 1. Introduction A fundamental principle of geotechnical engineering is that a change in total stress will result in a change in pore pressure (Skempton 1954; Mitchell 2005). This behavior is [...]

The Transportation Safety Board of Canada (TSB) maintains the Rail Occurrence Database System (RODS). This database contains information on all types of rail occurrences including derailments that must be reported by all Canadian railway operators. This paper analyzes the derailments that occurred on Canadian main track network between 2001 and 2014. The results from the analysis show that between 2001 and 2014 there was an overall decreasing trend in the number and intensity of main track derailments, derailments involving dangerous goods cars, and the number of derailments resulting in the release of dangerous goods. The RODS data was further analyzed to evaluate the frequency of the differing causes of derailments and the severity of the resulting incidents. The most common and severe derailment causes resulted from rail breaks, track geometry, and environmental conditions. Derailment velocity was also found to have an impact on the severity, with higher velocities resulting in a greater number of derailed rolling stock. Key words: railroad, dangerous goods, derailments. Le Bureau de la securite des transports du Canada (BST) maintient la Base de donnees sur les evenements ferroviaires (RODS). Cette base de donnees contient des informations sur tous les types d'evenements ferroviaires y compris les deraillements qui doivent etre signales par tous les exploitants ferroviaires canadiens. Dans le cadre de cette etude, on analyse les deraillements qui se sont produits sur le reseau canadien des voies principales entre 2001 et 2014. Les resultats de l'analyse indiquent qu'entre 2001 a 2014 il y a eu une tendance generale a la baisse du nombre et de l'intensite des deraillements sur les voies principales, des deraillements impliquant des wagons de marchandises dangereuses et du nombre de deraillements entrainant le deversement de marchandises dangereuses. Les donnees de la Base de donnees sur les evenements ferroviaires ont fait l'objet d'une analyse plus poussee pour evaluer la frequence des diverses causes de deraillements et la gravite des incidents qui s'en sont suivis. Les deraillements les plus communs et graves sont causes par des bris de rail, la geometrie de la voie et les conditions ambiantes. La vitesse au moment du deraillement s'est aussi averee avoir une incidence sur la gravite, ainsi des vitesses plus elevees entrainent un plus grand nombre d'evenements de materiel roulant deraille. [Traduit par la Redaction] Mots-cles: chemins de fer, marchandises dangereuses, deraillements., Introduction Canada currently has the third largest railway network in the world (Transportation Safety Board of Canada 2016a), at approximately 48 000 route kilometres of track (Transport Canada 2016a) (Fig. [...]

Falling weight deflectometer (FWD) testing was conducted along with embankment and subgrade sampling over 210 km (130 miles) of Canadian National Railway's Lac La Biche Subdivision, which runs between Edmonton and Fort McMurray, as a part of a larger investigation of the line for increased axle loads. The resulting measurements were evaluated for their ability to identify soft subgrades. Two analyses were conducted to this end. First, the statistical distribution of peak deflections recorded by the FWD was investigated for different types of subgrade material. Second, the properties of track substructure were studied by characterizing the deflection time histories using a dynamic model of a single mass on a viscoelastic foundation and least-squares curve fitting. Four characteristic types of deflection time histories were identified for differing substructure conditions. Simplified dynamic modelling of railway track substructure showed that where relatively thick embankment exists over subgrade, the response of track is overdamped behavior. Key words: railway substructure, falling weight deflectometer, subgrade, thickness of embankment, overdamped. Les essais de Deformation par chute de masse ('falling weight deflectometer'(FWD)) ont ete effectues avec le remblai et l'echantillonnage du sol de fondation sur 210 km (130 miles) de la filiale Canadian National Railways Lac La Biche qui relie Edmonton a Fort McMurray, dans le cadre d'une recherche d'envergure de la ligne pour les charges accrue par essieu. Les resultats des mesures ont ete evalues pour leur capacite a identifier des sols de fondation souple. Deux analyses ont ete menees a cette fin. Tout d'abord, la distribution statistique des deflexions pic enregistre par la FWD a ete etudiee pour differents types de materiaux de sols de fondation. Deuxiemement, les proprietes de l'infrastructure de la voie ont ete etudiees par la caracterisation de l'historique de deflexion en temps, obtenue selon un modele dynamique de masse unique sur base de fondation viscoelastique et avec des correlations en courbe a moindres carres. Quatre types de caracteristiques historiques de deflexion en temps ont ete identifies pour differentes conditions de sous-structure. La modelisation dynamique simplifiee de sous- structure de voie de chemin de fer ont montre qu'ou un remblai relativement epais existe sur un sol de fondation, la reponse de la voie est un comportement trop amorti. [Traduit par la Redaction] Mots-cles : sous-structure de chemin de fer, deflectometre de chute de poids, sol de fondation, epaisseur de remblai, suramortie., Introduction Increasing traffic and heavier axle loads on North American secondary freight railroad lines have been motivating the industry to find new methods to assess the condition of existing infrastructure [...]

This paper presents the pore pressure behaviour observed within peat beneath a newly constructed railway embankment. Piezometers installed at different depths beneath the structure showed episodic increases in pore pressure above hydrostatic pressure followed by a rapid pore pressure decrease. It was postulated that this fluctuation in pore pressure was due to the movement and expulsion of gases within the peat. Investigations were conducted in the laboratory to replicate this pore pressure response. The peat specimens were subjected to isotropic consolidation, within a triaxial cell, at constant confining pressure while measuring the change in the specimen's pore pressure and volume. The results of this investigation indicate that the gas bubbles move through the channeled network of voids towards the drainage boundary where they restrict the flow of water, which results in the increase of pore pressure towards an upper limit or escape pressure, ultimately causing an expulsion of gas bubbles. This expulsion of bubbles results in a rapid drop in pore pressure and volume change within the specimen. The implications of the volume change associated with this pore pressure behaviour are discussed. Key words: fibrous peat, gas bubbles, pore pressure, escape pressure. Le present article decrit les variations de pression interstitielle observees dans de la tourbe situee sous un remblai ferroviaire recemment construit. Des piezometres installes a differentes profondeurs sous le remblai ont montre que la pression interstitielle augmentait de maniere episodique jusqu'il depasser la pression hydrostatique, puis diminuait rapidement. On est parti du principe que cette fluctuation de la pression interstitielle etait due au deplacement et a l'expulsion des gaz contenus dans la tourbe. Des etudes ont ete realisees en laboratoire pour reproduire ces variations de la pression interstitielle. Les specimens de tourbes etudies ont subi une consolidation isotrope, a l'interieur d'une cellule triaxiale, a pression de confinement constante, pendant que l'on mesurait les variations de pression interstitielle et de volume de ces memes specimens. Les resultats de l'etude realisee montrent que les bulles de gaz se deplacent a travers le reseau de canaux forme par les vides en direction de la barriere de drainage, au niveau de laquelle elles empechent l'ecoulement de l'eau, ce qui entraine l'augmentation de la pression interstitielle jusqu';! une limite superieure de pression ou pression d'evacuation, et finit par provoquer l'expulsion des bulles de gaz. Cette expulsion des bulles de gaz entraine une chute rapide de la pression interstitielle dans le specimen et une variation du volume de ce dernier. Les consequences de la variation de volume associee a la fluctuation de la pression interstitielle sont decrites dans le present article. [Traduit par la Redaction] Mots-cles : tourbe fibreuse, bulles de gaz, pression interstitielle, pression d'evacuation., Introduction Peat consists of a fibrous material comprising fragments of long stems, leaves, and peat fibres, and a decomposed amorphous material (Landva 2007). The amorphous peats result from a greater [...]

Fourteen large landslides have occurred within a 10 km stretch of the Thompson River Valley south of Ashcroft, British Columbia. The slides have had movements ranging from rapid (metres per hour) to very slow, and the largest slides have volumes approaching 15.0 x 106 [m.sup.3]. Investigations of these slides have been conducted since the early failures of the slopes were noted in the 1860s, and have continued with the periodic reactivations and slope movements since then. This paper focuses on the Ripley Slide, which is one of the slides within the Thompson River Valley. This slide is a very slow-moving landslide, which has recently been reactivated. This landslide is crossed by a major transportation corridor and has therefore been the subject of ongoing geotechnical investigation and instrumentation. The results of this investigation are interpreted in light of the wealth of accumulated knowledge from more than a century of geotechnical investigation within this valley. The data collected from the landslide show that, like other slow-moving landslides in this valley, the seasonal fluctuations of the Thompson River elevation strongly influence the instability and the rate of slope movement. Continuous global positioning system monitoring of the movement of the landslide combined with measurement of the pore pressures within the sliding mass and elevation of the river have allowed for an empirical correlation between the limit equilibrium method modelled factor of safety and the velocity of the landslide. Key words: limit equilibrium method, slope stability, slope velocity, slope monitoring, railway. Quatorze grands glissements de terrain se sont produits a l'interieur d'une section de 10 km dans la vallee de la riviere Thompson au sud d'Ashcroft, en Colombie-Britannique. Les glissements ont presente des mouvements variant de rapides (metres par heure) a tres lents, et les plus gros glissements avaient des volumes approchant 15.0 x [10.sup.6] [m.sup.3]. Des etudes sur ces glissements ont ete realisees depuis les premieres ruptures observees dans les annees 1860, et ont continue en raison des reactivations periodiques et des mouvements des pentes depuis cette periode. Cet article s'interesse a un des glissements a l'interieur de la vallee de la riviere Thompson, le glissement Ripley. Ce glissement, qui a recemment ete reactive, bouge tres lentement. Ce glissement est croise par un corridor de transport majeur et ainsi a ete le sujet d'investigations et d'instrumentation geotechniques en continu. Les resultats de cette investigation sont interpretes en considerant lavaste connaissance acquise par plus d'un siecle d'etudes geotechniques a l'interieur de cette vallee. Les donnees obtenues du glissement, a l'instar des autres glissements lents dans la vallee, indiquent que les fluctuations saisonnieres de l'elevation de la riviere Thompson influencent significativement l'instabilite et le taux de mouvement de la pente. Le suivi GPS en continu du mouvement du glissement, combine avec des mesures de la pression interstitielle a l'interieur de la masse en mouvement et de l'elevation de la riviere, ont permis d'etablir une correlation empirique entre le facteur de securite modelise avec la methode de l'equilibre limite et la vitesse du glissement de terrain. [Traduit par la Redaction] Mots-cles: methode de l'equilibre limite, stabilite de pente, vitesse de pente, suivi de pente, chemin de fer., Introduction The Thompson River Valley between Ashcroft and Spences Bridge has been the site of several large landslides (Stanton 1898). The map shown in Fig. 1 presents locations of 14 [...]

Increasing traffic and speeds on passenger rail lines, and a short season for maintenance work, have motivated the industry to find new methods to assess the condition of existing infrastructure and determine where upgrades are required. In this study, acceleration data from the car body and axle boxes of a revenue car over 92 km of a Canadian passenger rail route in Ontario were collected for two purposes: first, to apply weighted filtering method according to ISO 2631-1997 standard as a technique to determine the locations which highly impact the ride quality and to investigate the effect of type of track features and speed on the ride quality; second, a new analytical method called the envelope of acceleration was applied to use the recorded accelerations to evaluate the alignment and surface roughness along the track. Since the alignment and surface roughness values are always positive and are calculated over a specified length (e.g. 9.5 m, 18.9 m, 38 m) an envelope technique was employed which uses spline interpolations over local maxima of the absolute magnitude of accelerations at every separated n samples corresponding to best fit with track roughness. The regression analysis between the envelope of accelerations and alignment and surface roughness presented a meaningful correlation and showed the applied method is a promising analytical technique to indicate rough sections of the track. The limitations to the application of envelope of acceleration are also discussed. [ABSTRACT FROM AUTHOR]

This paper presents the deformation and pore-water pressure response within peat foundations below three different railway embankments in response to cyclic heavy axle loading. The study sites include two at Canadian National (CN) Railway's Edson and Lac-La-Biche subdivisions in northern Alberta, and one at CN's Levis subdivision in southeastern Quebec. The three sites were instrumented to monitor the spatial distribution of strain, pore pressure generation, and stress, and the distribution of horizontal cyclic displacement with depth during the passage of trains. The horizontal cyclic displacement with depth was measured using a ShapeAccelArray (SAA). An analysis was conducted to determine how close the peat is to yielding under heavy axle loads. This analysis was based on the elastic response determined from undrained triaxial testing, a constitutive model developed for peat, and finite element modelling. The field response and the numerical modelling suggest that the embankments at the northern Alberta sites are stable under current loading conditions. The highest potential for yielding at these sites occurs just beneath the embankment and at the interface between the peat and underlying stiffer soil. At the Levis site the analysis suggests that a recently constructed ditch concentrates shear stress at a location where the principal stress orientation corresponds to a reduced strength of peat and may have increased the potential for yielding. Key words: fibrous peat, anisotropy, stiffness, shear strength, embankment, railroad, railway. Cet article presente revolution des deformations et des pressions interstitielles a l'interieur de fondations en tourbe sous trois remblais de chemin de fer differents soumis a des fortes charges par essieu cycliques. Les sites a l'etude incluent deux sites sur les subdivisions Edson et Lac-La-Biche du chemin de fer Canadian National (CN) au nord de l'Alberta, et un site sur la subdivision Levis du CN au sud du Quebec. Les trois sites ont ete instrumentes pour mesurer la distribution spatiale des deformations, la generation des pressions interstitielles et des contraintes, et la distribution du deplacement horizontal cyclique avec la profondeur durant le passage des trains. Le deplacement horizontal cyclique selon la profondeur a ete mesure avec un ShapeAccelArray (SAA). Une analyse a ete realisee pour determiner si la tourbe est pres de ceder sous les fortes charges par essieu. Cette analyse est basee sur le comportement elastique determine a partir d'essais triaxiaux non draines, d'un modele constitutif developpe pour la tourbe, et la modelisation par elements finis. Le comportement sur le terrain et la modelisation numerique suggerent que les remblais aux sites du nord de l'Alberta sont stables dans les conditions actuelles de chargement. L'emplacement ayant plus grand potentiel de ceder a ces sites est situe tout juste sous le remblai a l'interface entre la tourbe et le sol plus rigide sous-jacent. Au site de Levis, l'analyse suggere qu'un fosse recemment construit concentre les contraintes de cisaillement a l'endroit ou l'orientation des contraintes principales correspond a de la tourbe ayant une resistance reduite, et peut avoir augmente le potentiel de ceder. [Traduit par la Redaction] Mots-cles: tourbe fibreuse, anisotropie, rigidite, resistance au cisaillement, remblai, chemin de fer, voie ferree., Introduction Allowable axle loads on Canadian railways have tripled since the original construction of the railway infrastructure. The volume of traffic on the main lines of the Canadian National (CN) [...]

This paper presents the results of a laboratory testing program involving consolidated undrained triaxial tests and direct shear tests on remoulded peat, remoulded peat fibre, and Shelby specimens of peat obtained from a field site located in the Edson subdivision of the Canadian National railway in Alberta, Canada. These results were analyzed within the frameworks of elastic behaviour of cross-anisotropic materials and shear strength of fibre-reinforced soil. Shelby specimens were found to be inherently cross-anisotropic, whereas the remoulded peat and peat fibre specimens showed a transition from isotropic to cross-anisotropic with increasing vertical strain and effective confining pressure. The horizontal stiffness of Shelby specimens was found to be 2.6 to 2.9 times their vertical stiffness. The shear strength of intact peat is made up of interparticle friction as well as tension in the peat fibres. A novel procedure for estimating the interparticle frictional strength of fibrous peat from CU triaxial test results is proposed. It involves extrapolating the linear strain-hardening portion of the stress-strain curve to obtain the deviatoric stress at zero axial strain and plotting the deviatoric stress values thus obtained against initial mean effective confining pressure to obtain the frictional strength. Using this procedure, a value of 31° was obtained for the interparticle friction, which compares favourably with a value of 31° obtained from direct shear tests. It is recommended that further studies be undertaken to assess if interparticle frictional strength is an appropriate strength parameter for evaluation of the stability of structures founded on fibrous peat. Key words: fibrous peat, triaxial testing, direct shear testing, anisotropy, stiffness, shear strength, railway. Cet article presente les resultats d'un programme d'essais en laboratoire impliquant des essais triaxiaux non draines et des essais de cisaillement direct faits sur de la tourbe remaniee, de la fibre de tourbe remaniee et des echantillons Shelby de tourbe provenant d'un site situe sur la subdivision Edson du chemin de fer du Canadian National en Alberta, Canada. Ces resultats sont analyses a l'aide des principes du comportement elastique de materiaux anisotrope en croix et de la resistance au cisaillement de sol renforce par des fibres. Les echantillons Shelby se sont reveles comme etant anisotrope en croix, tandis que la tourbe remaniee et les echantillons de fibre de tourbe presentent une transition entre l' isotropie et l' anisotropie en croix lorsque les deformations verticales et la pression effective de confinement augmentent. La rigidite horizontale des echantillons Shelby etait de 2,6 a 2,9 fois leur rigidite verticale. La resistance au cisaillement de la tourbe intacte est composee de la friction interparticule ainsi que de la tension dans les fibres de la tourbe. Une nouvelle procedure est proposee pour estimer la force frictionnelle interparticule de la tourbe fibreuse a partir des resultats d'essais triaxiaux CU. Cette procedure implique l'extrapolation de la portion lineaire d' ecrouissage de la courbe de contrainte-deformation pour obtenir la contrainte deviatorique a une deformation axiale nulle, et de representer graphiquement les valeurs de contrainte deviatorique ainsi obtenues versus la pression effective de confinement moyenne pour obtenir la force frictionnelle. Grace a cette procedure, une valeur de 31° a ete obtenue pour la friction interparticule, ce qui se compare bien a une valeur de 31° obtenue avec des essais de cisaillement direct. Il est recommande que des etudes supplementaires soient entreprises pour determiner si la force frictionnelle interparticule est un parametre de resistance approprie pour l'evaluation de la stabilite de structures ayant des fondations dans de la tourbe fibreuse. Mots-cles : tourbe fibreuse, essais triaxiaux, essais de cisaillement direct, anisotropie, rigidite, resistance au cisaillement, chemin de fer. [Traduit par la Redaction], Introduction Allowable axle loads on Canadian railways have tripled since the construction of a majority of the railway infrastructure. The volume of traffic on the main lines of the Canadian [...]