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With a newly developed swelling pressure apparatus, swelling pressure tests were conducted to elucidate initial water content and specimen preparation method effects on swelling pressures (swelling pressure evaluation curve and equilibrium swelling pressure) of Kunigel-V1 bentonite. X-ray diffraction (XRD) tests were conducted to investigate the initial water content and specimen preparation method effects on basal spacing, including basal spacings of specimens before and after wetting. Experiments produced the following results. (1) The swelling pressure evaluation curve changed from a line with peak and valley to a line with early-stage steady rise as increasing initial water content. (2) The initial water content and specimen preparation method exerted no apparent effect on the equilibrium swelling pressure. (3) Basal spacing of the specimen before wetting was affected not only by the initial water content but also by the specimen preparation method. (4) The initial water content did not influence the basal spacing of the specimen after wetting. It was only affected by the specimen preparation method. Based on the swelling pressure evaluation curve patterns, swelling mechanisms during saturation for specimens with different initial conditions were discussed. Initial water content and specimen preparation method effects on equilibrium swelling pressure were explained carefully with basal spacings. Key words: initial water content, specimen preparation method, swelling pressures, XRD, 1. Introduction The deep geological disposal method was selected to address high-level radioactive waste (HLW) from the nuclear power industry by different countries (e.g., SKB 2011; NUMO 2022). In Japan, [...]

Vibrating-wire piezometers provide a number of advantages over the traditional hydraulic piezometer design. There are currently many methods and configurations for installing vibrating-wire piezometers, the most common being: single piezometers in sand packs (SP), multilevel piezometers in sand packs (MLSP), and fully grouted multilevel piezometers using either bentonite (FGB) or cement-bentonite grout (FGCB). This study assesses the performance of these four different installation methods at a field site possessing complex stratigraphy, including glacial and marine sediments. To accomplish this objective, pore pressure data recorded between December 2017 and July 2019 were analyzed. Data indicate that SP, MLSP, and FGB piezometers performed most reliably, because piezometers installed at the same depth with these methods recorded similar pressure variations that were coherent with the hydrogeological setting. Of the two fully grouted installations using cement-bentonite grout, one installation failed completely due to a hydraulic short circuit, likely caused by preferential flow occurring along the wires of the embedded instruments. The lack of a standard method for mixing cement-bentonite grout at the time of construction likely contributed to the failure of the FGCB installations, as the grout mixture used in this study was likely too viscous to provide a suitable seal. Key words: vibrating-wire piezometers, St. Lawrence Lowlands, fully grouted methods. Les piezometres a fil vibrant offrent un certain nombre d'avantages par rapport aux piezometres hydrauliques traditionnels. Il y a actuellement de nombreuses methodes et configurations pour installer des piezometres a fil vibrant, les plus courantes etant les suivantes : piezometres simples dans des paquets de sable (SP), piezometres multiniveaux dans des paquets de sable (MLSP) et piezometres multiniveaux entierement scelles a l'aide de bentonite (FGB) ou de coulis de ciment-bentonite (FGCB). Cette etude evalue les performances de ces quatre methodes d'installation differentes sur un site de terrain presentant une stratigraphie complexe, comprenant des sediments glaciaires et marins. Pour atteindre cet objectif, les donnees de pression interstitielle enregistrees entre decembre 2017 et juillet 2019 ont ete analysees. Les donnees indiquent que les piezometres SP, MLSP et FGB ont donne les resultats les plus fiables, car les piezometres installes a la meme profondeur avec ces methodes ont enregistre des variations de pression similaires, coherentes avec le contexte hydrogeologique. Parmi les deux installations entierement scellees a l'aide d'un coulis de ciment-bentonite, l'une d'elles s'est completement effondree en raison d'un courtcircuit hydraulique, probablement cause par un ecoulement preferentiel le long des fils des instruments encastres. L'absence d'une methode standard pour le melange de coulis de ciment-bentonite au moment de la construction a probablement contribue a l'echec des installations de BGCF, car le melange de coulis utilise dans cette etude etait probablement trop visqueux pour assurer une etancheite adequate. [Traduit par la Redaction] Mots-cles : piezometres a fil vibrant, basses terres du Saint-Laurent, methodes a scellement complet., 1. Introduction In the province of Quebec, 89% of the population of the province lives within the depositional extent of the Champlain Sea sediments, which were deposited by a marine [...]

A method for determination of the active earth pressure exerted by a cohesionless backfill, subjected to water seepage from a high water table, on a retaining structure is presented. The method comprises a numerical procedure based on the boundary element method (BEM) for the seepage analysis and a trial wedge method for the limit equilibrium analysis. The numerical results of the seepage analysis are presented as normalized charts that can be used in the trial wedge method without recourse to the BEM computer code. The main benefits of the proposed analysis are the simplicity of use and the small amount of data necessary. For the seepage analysis, only the phreatic line exit point height at the retaining structure face is required. Numerical results obtained for a proposed example of a retaining wall show the influence of the water seepage on the active earth pressure. The analysis method also can deal with cases of soil anisotropy with respect to the permeability. Key words: earth pressure, water seepage, retaining structures, limit equilibrium, boundary element method. On presente ici une methode permettant de determiner la pression active des terres exercee par un remblai sans cohesion, soumis a une infiltration d'eau provenant d'une nappe phreatique dont le niveau est eleve, sur un ouvrage de soutenement. La methode comporte une approche numerique basee sur la methode des elements finis de frontiere (MEFF) et servant a analyser l'infiltration d'eau une methode d'essai sur coins de sol permettant d'effectuer l'analyse de l'equilibre limite. Les resultats obtenus a l'aide de la methode numerique d'analyse de l'infiltration sont presentes sous la forme de diagrammes normalises, que l'on peut utiliser dans le cadre de la methode d'essai sur coins sans avoir recours au programme informatique base sur la MEFF. L'analyse proposee a pour principaux avantages d'etre simple a utiliser et de ne necessiter que peu de donnees. L'analyse de l'infiltration necessite seulement de connaitre la hauteur du point de sortie de la surface de la nappe phreatique sur la paroi de l'ouvrage de soutenement. Les resultats obtenus a l'aide de la methode numerique dans le cas de l'exemple de mur de soutenement propose mettent en evidence l'influence de l'infiltration d'eau sur la pression active des terres. La methode d'analyse proposee permet egalement d'etudier la permeabilite des sols anisotropes. [Traduit par la Redaction] Mots-cles: pression des terres, infiltration d'eau, ouvrages de soutenement, equilibre limite, methode des elements finis de frontiere., Introduction The presence of water in soil voids has a large influence on the lateral earth pressure on soil retaining structures. The hydrostatic pressure due to water accumulation behind the [...]

A numerical method is developed to evaluate the passive earth pressure coefficients for an inclined rigid retaining wall resting against a horizontal cohesionless backfill. A composite failure surface comprises a log spiral, and its tangent is assumed in the present study. The unique failure surface is identified based on the limit equilibrium approach coupled with the Kotter equation (published in 1903). Force equilibrium conditions are used to evaluate the magnitude of the passive thrust, whereas the moment equilibrium condition is employed to determine the location of the passive thrust. The distinctive feature of the present study is that no assumption is required to be made regarding the point of application of the passive thrust, which would otherwise be an essential criterion with respect to the several limit equilibrium based investigations available in the literature. The passive earth pressure coefficients, [K.sub.pγ], are evaluated for various values of soil frictional angle φ, wall frictional angle δ, and wall inclination angle γ, and compared with the existing results. Key words: inclined retaining wall, cohesionless backfill, Kotter equation, limit equilibrium, passive earth pressure coefficients, passive thrust location. Une methode numerique est developpee pour evaluer les coefficients de pression passive des terres d'un mur de soutenement incline rigide s'appuyant contre un remblai sans cohesion horizontal. Dans la presente etude, on prend l'hypothese d'une surface de rupture composite comportant une spirale logarithmique et sa tangente. Cette surface de rupture unique est determinee a partir de la methode de l'equilibre limite couplee a l'equation de Kotter (publie en 1903). Les conditions d'equilibre des forces sont utilisees pour evaluer l'amplitude du chevauchement passif, tandis que la condition d'equilibre des moments sert a localiser ce dernier. La singularite de la presente etude vient du fait qu'il n'est pas necessaire de formuler une hypothese concernant le point d'application du chevauchement passif, alors que ce dernier constitue un critere essentiel dans les quelques etudes basees sur l'equilibre limite disponibles dans la litterature. Les coefficients de pression passive des terres, [K.sub.yγ], sont evalues pour differentes valeurs d'angle de frottement du sol φ, d'angle de frottement du mur δ et d'angle d'inclinaison du mur γ, puis sont compares avec les resultats existants. [Traduit par la Redaction] Mots-cles : mur de soutenement incline, remblai sans cohesion, equation de Kotter, equilibre limite, coefficients de pression passive des terres, localisation du chevauchement passif., Introduction A study on earth pressures is an interesting topic in the field of geotechnical engineering. Numerous investigators have been working in this research area, as understanding the behaviour of [...]

This paper describes a method developed to link the measured piezocone dissipation excess pore-water pressure (Δu) to the soil undrained shear strength ([s.sub.u]). In cohesive soils, both Δu and [s.sub.u] are dependent on the same variables (compressibility, stress state, stress history), which allows them to be related by the theoretical cavity expansion--critical state framework. A mathematical derivation is presented to demonstrate that the ratio of normalized maximum excess pore pressure and the normalized undrained shear strength fluctuates around a mean value, being affected by soil strength and compressibility and independent of stress history. The predicted [s.sub.u] values obtained from the proposed approach are calibrated against field vane shear strength in both normally consolidated (monotonic dissipation tests) and overconsolidated soils (dilatory dissipation tests). Reported results are consistent and encourage the use of the method in engineering practice. On a routine basis, [s.sub.u] estimated from pore pressure can be compared with values predicted from penetration resistance, adding desired redundancy for purposes of error detection when interpreting cone penetration testing with pore pressure measurement (CPTU) data. Key words: excess pore-water pressure, undrained shear strength, dissipation tests, cone penetration testing with pore pressure measurement (CPTU). Le present article decrit une methode nouvellement elaboree permettant de relier les mesures de la dissipation de l'exces de pression interstitielle de l'eau dans les pores a l'aide d'un piezocone (Δu) a la resistance au cisaillement non draine du sol ([s.sub.u]). Dans les sols cohesifs, Δu et [s.sub.u] dependent des memes variables (compressibilite, etat de contrainte, historique des contraintes) et peuvent etre reliees dans un cadre theorique combinant l'expansion de cavite avec l'etat critique. Une derivation mathematique est exposee afin de demontrer que le rapport entre l'exces maximum normalise de pression interstitielle dans les pores et la resistance normalisee au cisaillement non draine oscille autour d'une valeur moyenne sous l'influence de la resistance et de la compressibilite du sol et independamment de l'historique des contraintes. Les valeurs predites de [s.sub.u] obtenues a partir de la methode proposee sont ajustees par rapport aux mesures scissometriques de resistance au cisaillement effectuees sur le terrain, dans le cas des sols normalement consolides (essais monotones de dissipation) et surconsolides (essais de dissipationdilatation). Les resultats obtenus sont coherents et encouragent les ingenieurs a mettre cette methode en pratique. On peut comparer de fa^on systematique les valeurs de la [s.sub.u] determinees a partir de la pression dans les pores a celles predites a partir de la resistance a la penetration tout en ajoutant la redondance souhaitee afin de reperer les erreurs d'interpretation des donnees des essais de penetration du cone avec la mesure des pressions interstitielle (CPTU). [Traduit par la Redaction] Mots-cles: exces de pression interstitielle de l'eau, resistance au cisaillement non draine, essais de dissipation, essais de penetration du cone avec la mesure des pressions interstitielle (CPTU)., Introduction Prediction of soil properties from piezocone test (cone penetration testing with pore pressure measurement, CPTU) data in cohesive soils is routinely carried out in geotechnical design. This is possible [...]

Methods of computation for soil heave based on an 'equivalent' net normal stress path approach often have built-in assumptions regarding the relationship between in situ matric suction, overburden stress, and swell pressure. The term 'matric suction equivalent' has been previously defined as the difference between in situ state of stress projected on the net normal stress plane (represented by swell pressure) and overburden stress. Correlations between matric suction, overburden stress, and swell pressure for matric suction values in excess of the air-entry value have not been well studied and are explored here for expansive soils. Filter paper (in-contact) and constant volume swell pressure tests were performed on undisturbed tube samples of expansive soils taken from Arizona, Colorado, and Texas. In general, the ratio of the matric suction equivalent to the matric suction decreases with increasing soil suction. An empirical relationship was established in which the matric suction equivalent was found to be proportional to the logarithm of the matric suction for in situ matric suctions greater than a certain value, termed as the 'intercept matric suction'. A correlation between the intercept matric suction and the soil's plasticity index (PI) was found for the clays of this study. The developed correlations represent a method for obtaining approximate estimates of in situ matric suction for expansive soils from PI and swell pressure data. Implications of the study findings for the use of an equivalent net normal stress approach for estimation of soil heave are explored. Key words: expansive soils, unsaturated soils, matric suction, matric suction equivalent, swell pressure, degree of saturation, heave prediction. Les methodes de calculs de soulevement de sol basees sur une approche avec contrainte normale nette << equivalente >> comportent souvent des hypotheses sur le lien entre la succion matricielle in situ, la pression lithostatique et la pression de gonflement. Le terme<>a ete precedemment defini comme la difference entre l'etat de contrainte in situ projete sur le plan de la contrainte normale nette (representee par la pression de gonflement) et la pression lithostatique. Les liens entre la succion matricielle, la pression lithostatique et la pression de gonflement pour les valeurs de succion matricielle depassant la charge capillaire critique n'ont pas encore ete formellement etudies et sont examines ici dans le cas des sols expansifs. Des essais de pression de gonflement sur papier filtre (en contact avec les echantillons) et a volume constant ont ete realises sur des tubes d'echantillons non perturbes de sols expansifs preleves en Arizona, au Colorado et au Texas. De fa^on generale, le quotient de l'equivalent succion matricielle par la succion matricielle diminue lorsque la succion du sol augmente. Une relation empirique a montre que l'equivalent succion matricielle semblait etre proportionnel au logarithme de la succion matricielle dans le cas ou cette derniere etait superieure a une certaine valeur qualifiee de << succion matricielle au point d'intersection >>. Une correlation entre la succion matricielle au point d'intersection et l'indice de plasticite (IP) du sol a ete decouverte dans le cas des argiles etudiees ici. Les correlations ainsi mises en evidence constituent une methode permettant d'obtenir des estimations approximatives de la succion matricielle in situ dans le cas des sols expansifs a partir des valeurs de l'IP et de la pression de gonflement. On evoque enfin les repercussions des decouvertes realisees dans la presente etude sur l'utilisation d'approches avec contrainte normale nette equivalente pour estimer le soulevement des sols. [Traduit par la Redaction] Mots-cles: sols expansifs, sols non satures, succion matricielle, equivalent succion matricielle, pression de gonflement, degre de saturation, prediction du soulevement., Introduction The vertical swelling of an expansive soil layer is generally referred to as heave. Existing methods for computing heave in response to soil wetting typically follow either an actual [...]

The hole erosion test (HET) is used in the study of soil erosion in the case of what is known as 'piping' when concentrated leaks occur. The HET enables the determination of soil erosion characteristics such as the critical shear stress along the pre-formed hole (pipe) and the coefficient of soil erosion. Normally, in the HET, the hydraulic gradient is determined from the difference between the piezometric heads measured at the inflow and outflow chambers (upstream and downstream of the soil specimen). Hydraulic analysis shows that such measurements ignore losses at the entrance and exit of the hole, causing the overestimation of the hydraulic gradient along the length of the hole, and thus the calculated shear stress. In this technical note, the results of preliminary analysis using the Bernoulli principle and of numerical study of the pressure conditions in the HET apparatus are shown. The turbulent flow in the HET apparatus was calculated using ANSYS commercial CFD (computational fluid dynamics) software. The analysis was performed for various hole entrance shapes. The conclusion of this note details the differences between traditionally determined hydraulic gradients and those numerically derived along the length of a hole. Key words: hole erosion test, piping, hydraulic gradient, shear stress, Bernoulli principle, turbulent flow modelling. L'essai d'erosion d'un trou (EET) est utilise pour etudier l'erosion du sol dans un cas connu en tant que << renard >>, lorsque des fuites concentrees se produisent. L'EET permet de determiner les caracteristiques d'erosion du sol, tels que la contrainte de cisaillement critique le long du trou preforme (renard) et le coefficient d'erosion du sol. Normalement, lors d'un EET le gradient hydraulique est determine a partir de la difference de tete piezometrique mesuree dans les chambres d'entree et de sortie (en amont et en aval de l'echantillon de sol). L'analyse hydraulique demontre que de telles mesures ignorent les pertes a l'entree et a la sortie du trou, ce qui surestime le gradient hydraulique le long du trou, donc la contrainte de cisaillement calculee. Dans cette note technique, on presente les resultats d'une analyse preliminaire a partir du principe de Bernouilli et une etude numerique des conditions de pression dans l'appareil d'EET. L'ecoulement turbulent dans l'appareil d'EET a ete calcule avec le logiciel de DCF (dynamique computationnelle des fluides) commercial ANSYS. L'analyse a ete realisee pour differentes formes d'entree de trou. La conclusion de cette note presente en details les differences entre les gradients hydrauliques determinees a l'aide des methodes traditionnelles de ceux derives numeriquement le long du trou. [Traduit par la Redaction] Mots-cles: essai d'erosion d'un trou, renard, gradient hydraulique, contrainte de cisaillement, principe de Bernouilli, modelisation d'ecoulement turbulent., Introduction Earth hydraulic structures (e.g., dams or levees) and their sub-bases can be eroded by seeping water. The failure of such structures while they are permanently or temporarily retaining water [...]

Reliable measurement of pressure within a particulate media has frustrated researchers in the field of soil mechanics and soil structure interaction for many years. The difficulty stems from the fact that most sensing systems involve compliance in the measurement concept. This compliance imparts a parasitic output to the measurement. In the past, researchers have attempted to calibrate this disturbance. Research has demonstrated that calibrations of this sort are dependent upon soil type, particle size, sensor geometry, and soil stiffness. Response of such sensors has been shown to be stress history- dependent: the response upon unloading maybe highly nonlinear, resulting in a high degree of hysteresis. Complications in the measurement of soil pressure within a soil mass are significantly more complex from those met in the measurement of soil pressure at a structural boundary and must be considered separately. This paper utilizes a concept called the Null Soil Pressure System. Null pressure sensors were embedded and tested in a series of uniformly graded soils with particle diameters ranging from less than 0.15 to 15 mm. The data indicates that the response of the null pressure sensor consistently exceeds the actual soil pressure by a value of 4% ± 3%. This outcome is seen to be independent of soil type, particle size, stiffness, and stress history. No hysteresis is noted between loading and unloading, and additional loading cycles align with that of the virgin loading segment. Key words: soil pressure measurement, granular soils, experimentation. L'obtention de mesures de pression fiables a l'interieur d'un milieu particulaire donne des maux de tete aux chercheurs dans les domaines de la mecanique des sols et de l'interaction sol-structure depuis plusieurs annees. La difficulte provient du fait que la plupart des systemes de sondes impliquent l'elasticite dans le concept de mesure. Cette elasticite ajoute un resultat parasite a la mesure. Dans le passe, les chercheurs ont tente de calibrer ce derangement. La recherche a demontre qu'un tel calibrage est dependant du type de sol, de la granulometrie, de la geometrie de la sonde et de la rigidite du sol. Les reponses de ces sondes ont ete demontrees comme etant dependantes de l'historique des contraintes, et la reponse en dechargement peut etre tres non lineaire, ce qui entrame un fort degre d'hysteresis. Les complications dans la mesure de la pression d'un sol a l'interieur d'une masse de sol sont significativement plus complexes que celles rencontrees lors de la mesure de la pression d'un sol a une frontiere structurelle, et doivent etre considerees separement. Cet article utilise un concept appele le <>. Des sondes de pression nulle ont ete enfouies et testees dans une serie de sols uniformement distribues avec des particules de diametre de moins de 0,15 a 15 mm. Les donnees indiquent que la reponse de la sonde de pression nulle excede la pression reelle du sol de fa^on consistante d'une valeur de 4 ± 3%. Ce resultat est independant du type de sol, de la granulometrie, de la rigidite et de l'historique des contraintes. Aucune hysteresis n'est observee entre le chargement et le dechargement, et les cycles de chargement additionnels sont alignes avec le segment original de chargement. [Traduit par la Redaction] Mots-cles: mesure de la pression du sol, sols granulaires, experimentation., Introduction Over recent years there has been a growing trend in geotechnical research to perform large-scale control testing or scaled centrifuge modeling to evaluate numerical and analytical computational techniques in [...]

The effect of initial particle fabric on the one-dimensional compression response of Fraser River sand was investigated. One-dimensional compression with lateral stress measurement was carried out on reconstituted Fraser River sand specimens using an instrumented oedometer. Laboratory specimens were reconstituted by air pluviation, tamping, and vibration and were prepared with an initial relative density ranging from medium loose to very dense. For Fraser River sand in one- dimensional compression, air-pluviated specimens yielded the highest values for the coefficient of lateral earth pressure at rest ([K.sub.o]), tamped specimens produced the lowest [K.sub.o] values, and vibrated specimens produced intermediate [K.sub.o] values. The results from the present study demonstrate that specimens resulting from different laboratory reconstitution methods (i.e., different initial particle fabrics) exhibit different one-dimensional compression responses and produce different [K.sub.o] values. A 'fabric factor' was introduced to account for the effect of the initial particle fabric on the measured coefficient of lateral earth pressure at rest. Using the fabric factor, the constant volume friction angle, and the specimen relative density, a new empirical equation defining the coefficient of lateral earth pressure at rest during normally consolidated loading is proposed. Key words: sand, one-dimensional compression, particle fabric, coefficient of lateral earth pressure at rest. L'effet de la structure initiale des particules de sable de la riviere Fraser sur leur comportement en compression unidimensionnelle a ete etudie. Des mesures de compression unidimensionnelle avec contraintes laterales ont ete realisees avec un odometre instrumente sur des echantillons reconstitues de sable de la riviere Fraser. Les echantillons de laboratoire ont ete reconstitues par pluviation a l'air, par pilonnage et par vibration, et ont ete prepares avec une densite relative initiale variant de moyennement lache a tres dense. Pour les echantillons de sable de la riviere Fraser en compression unidimensionnelle, les echantillons prepares par pluviation a l'air ont donne les valeurs les plus elevees du coefficient de pression laterale des terres au repos ([K.sub.o]), les echantillons pilonnes ont produit les valeurs de [K.sub.o] les plus faibles, et les echantillons vibres ont genere des valeurs de [K.sub.o] intermediaires. Les resultats de cette etude demontrent que les echantillons produits par differentes methodes de reconstitution de laboratoire (c'est-a-dire differentes structures initiales des particules) presentent des comportements en compression unidimensionnelle differents, et produisent des valeurs de [K.sub.o] differentes. Un facteur de ≪ structure des particules ≫ a ete introduit pour tenir compte de l'effet de la structure initiale des particules sur le coefficient de pression laterale des terres au repos mesure. A partir du facteur de structure des particules, de l'angle de friction a volume constant et de la densite relative de l'echantillon, une nouvelle equation empirique qui defini le coefficient de pression laterale des terres au repos durant le chargement normalement consolide est proposee. [Traduit par la Redaction] Mots-cles: sable, compression unidimensionnelle, structure des particules, coefficient de pression laterale des terres au repos., Introduction The coefficient of lateral earth pressure at rest, [K.sub.o], is used to define the stress state in soil where no lateral deformation occurs. [K.sub.o] is expressed as the ratio [...]

This paper investigates the magnitude and distribution of earth pressure on a support system in open cuts in jointed rock mass for the safer and more economical design and construction of earth-retaining structures installed in a rock stratum. The paper first investigates the limitations of previous research on earth pressure and then addresses them to provide a numerical parametric study based on the discrete element method, which can consider the joint characteristics of a rock stratum. The controlled parameters include rock type, joint conditions (shear strength and angle of joints), and wall type. The magnitude and distribution of earth pressure are investigated based on interactions between the ground and the retaining structure. In addition, earth pressure in the rock stratum is compared with Peck's earth pressure for soil ground. The results indicate that the magnitude and distribution of earth pressure in jointed rock mass are strongly influenced by rock type, joint conditions, and wall type, and that this pressure can be very different from that in soil ground. Furthermore, the results of numerical tests are compared with field measurements, and the comparison shows a reasonable agreement. This paper provides useful data for the assessment of earth pressure in designing support systems for jointed rock mass. Key words: rock excavation, support system, earth pressure, joint condition, soil-structure interaction, wall type. Cet article investigue la magnitude et la distribution de la pression des terres sur le systeme de support dans ouvertures dans des masses rocheuses jointees, dans l'optique d'une conception et construction plus securitaire et plus economique de structures de retention installees dans une couche de roche. L'article presente l'etude des limites des recherches anterieures sur la pression des terres, pour ensuite y repondre a l'aide d'une etude numerique parametrique basee sur la methode des elements discrets, qui peut considerer les caracteristiques jointes d'une couche de roche. Les parametres controles incluent le type de roche, les conditions des joints (la resistance au cisaillement et l'angle des joints), et le type de face. La magnitude et la distribution de la pression des terres sont evaluees selon les interactions entre le sol et la structure de retention. De plus, la pression des terres dans la couche de roche est comparee avec la pression des terres de Peck pour le sol. Les resultats indiquent que la magnitude et la distribution de la pression des terres dans la masse de roche jointee sont fortement influencees par le type de roche, les conditions des joints et le type de face, et que cette pression peut etre tres differente de celle dans un sol. En outre, les resultats des essais numeriques sont compares avec des mesures de terrain, et la comparaison demontre une correspondance raisonnable. Cet article offre des donnees utiles pour l'evaluation de la pression des terres dans la conception de systemes de support pour une masse de roche jointee. [Traduit par la Redaction] Mots-cles: excavation dans la roche, systeme de support, pression des terres, condition des joints, interaction sol- structure, type de face., Introduction Various ground excavation works in complex urban areas can give rise to several problems for surrounding environments. In particular, miscalculating earth pressure on excavation walls may cause the collapse [...]

Two cast-in-place reinforced concrete box culverts (Longs Creek and McBean Brook culverts) with similar geometry were instrumented to monitor earth pressures. The Longs Creek structure is a 7.30 m wide by 4.53 m high double-cell box under 14.10 m of fill, constructed using the positive projection installation (PPI) method. The McBean Brook structure is a 6.75 m wide by 4.65 m high double-cell box culvert under 25.10 m of fill, constructed using the induced trench installation (ITI) method. Earth pressures were monitored as the fill height above the culvert was increased for both structures. Data from the McBean Brook culvert at a fill height of 14.40 m are compared with the data from the Longs Creek culvert. The similar geometries of these two prototype culverts provide a unique opportunity to compare their performance based on the two different installation methods. For a comparable height of soil cover, measured vertical earth pressures on the roofs were 0.94 and 0.56 times the overburden pressures for the Longs Creek (PPI) and the McBean Brook (ITI) culverts, respectively. The average measured lateral earth pressure was 0.32 times the overburden pressure at the Longs Creek culvert (PPI), and 0.46 times the overburden pressure at the McBean Brook culvert (ITI). Data from the McBean Brook culvert pertaining to base contact pressure are also presented, but could not be compared directly with the Longs Creek culvert, as base pressures were not measured. Measured pressures at the base of the McBean Brook culvert show the presence of drag forces developed on the sidewalls of box culverts. Results from centrifuge model testing are also presented and compared with the field-measured pressures. Key words: induced trench, earth pressure, box culvert, soil arching, centrifuge testing, high embankments. Deux ponceaux rectangulaires coules sur place et renforces (ponceaux Longs Creek et McBean Brook), qui ont une geometrie similaire, ont ete instrumentes afin de mesurer les pressions des terres. La structure Longs Creek est un ponceau rectangulaire a double cellule de 7,30 m de largeur par 4,53 m de hauteur, place sous 14,10 m de remblai, et construit a l'aide de la methode d'installation par projection positive (IPP). La structure McBean est un ponceau rectangulaire a double cellule de 6,75 m de largeur par 4,65 m de hauteur, place sous 25,10 m de remblai, construit avec la methode d'installation de tranchee induite (ITI). Les pressions des terres sont suivies depuis que la hauteur du remblai sur le ponceau a ete augmentee pour les deux structures. Les donnees du ponceau McBean Brook a une hauteur de remblai de 14,40 m sont comparees aux donnees du ponceau Longs Creek. La geometrie similaire de ces deux prototypes de ponceaux offre une opportunite unique de comparer les performances selon les differentes methodes d'installation. Pour une hauteur de remblai comparable, les pressions des terres verticales mesurees sur les toits etaient de 0,94 et 0,56 fois les pressions des terres pour le ponceau Longs Creek (IPP) et le ponceau McBean Brook (ITI), respectivement. La pression des terres laterale moyenne etait de 0,32 fois la pression des terres au ponceau Longs Creek (IPP), et 0,46 fois la pression des terres au ponceau McBean Brook (ITI). Les donnees du ponceau McBean Brook en lien avec la pression de contact a la base sont aussi presentees mais n'ont pas pu etre comparees directement avec le ponceau Longs Creek, puisque les pressions a la base n'y ont pas ete mesurees. Les pressions mesurees a la base du ponceau McBean Brook demontrent la presence de forces de trainee developpees sur les murs de cote des ponceaux rectangulaires. Des resultats obtenus a partir d'essais en centrifuge sont aussi presentes et compares aux mesures de pression sur le terrain. Mots-cles : tranchee induite, pression des terres, ponceau rectangulaire, effet d'arche, essai en centrifuge, digues elevees., Introduction Modern highway construction and development sometimes requires construction of high embankments (fill height above the culvert top, H ≥ 10 m) over underground rigid and flexible structures. The high [...]

Earth pressure data from the field instrumentation of a cast-in-place reinforced rectangular box culvert are presented in this paper. The instrumented culvert is a 2.60 m by 3.60 m double-cell reinforced cast-in-place rectangular box buried under 25.10 m of fill constructed using the induced trench installation (ITI) method. The average earth pressure measured across the roof was 0.42 times the overburden pressure, and an average of 0.52 times the overburden pressure was measured at mid-height of the culvert on the sidewalls. Base contact pressure under the rectangular box culvert was also measured, providing field-based data demonstrating increased base pressure resulting from downward drag forces developed along the sidewalls of the box culvert. An average increase of 25% from the measured vertical earth pressures on the roof plus the culvert dead load (DL) pressure was calculated at the culvert base. A model culvert was also tested in a geotechnical centrifuge to obtain data on earth pressures at the top, sides, and base of the culvert. The data from the centrifuge testing were compared with the prototype structure, and the centrifuge test results agreed closely with the measured field prototype pressures, in spite of the fact that full similitude was not attempted in centrifuge testing. Key words: induced trench, earth pressure, box culvert, soil arching, centrifuge testing, high embankments. Cet article presente des donnees de pressions des terres provenant d'instrumentation sur le terrain d'un ponceau rectangulaire renforce et coule en place. Le ponceau instrumente est un ponceau rectangulaire renforce a double cellule de 2,60 m par 3,60 m, coule en place sous 25,10 m de remblai, et construit avec la methode d'installation de tranchee induite (ITI). La pression des terres moyenne sur la paroi superieure etait de 0,42 fois la pression des terres, et une moyenne de 0,52 fois la pression des terres etait mesuree a la mi-hauteur des murs du ponceau. La pression de contact a la base sous le ponceau rectangulaire a aussi ete mesuree, ce qui permet de demontrer a l'aide de resultats de terrain qu'une augmentation de la pression a la base est causee par les forces de trainee vers le bas developpees le long des murs des cotes du ponceau rectangulaire. Une augmentation moyenne de 25 % de la pression des terres verticale mesuree sur la paroi superieure, en plus de la pression de charge morte du ponceau, a ete calculee a la base du ponceau. Un ponceau modele a aussi ete teste dans une centrifuge geotechnique afin d'obtenir des donnees sur les pressions des terres au haut, sur les cotes, et a la base du ponceau. Les donnees des essais en centrifuge ont ete compares avec la structure prototype, et les resultats d'essais en centrifuge correspondent bien avec les mesures de pressions sur le prototype de terrain, malgre que les essais en centrifuge ne tentaient pas d'etre totalement similaires au terrain. Mots-cles : tranchee induite, pression des terres, ponceau rectangulaire, effet d'arche, essai en centrifuge, digues elevees. [Traduit par la Redaction], Introduction Routing and construction of modern highways often require high embankment fills (fill height above culvert top, H ≥ 10 m) crossing over underground rigid and flexible culverts, thereby resulting [...]

Volumetric behaviour is a fundamental consideration in unsaturated soil constitutive modelling. It is more complex than when the soil is saturated, as unsaturated soils exhibit a range of responses such as swelling and collapse under wetting and shrinkage and cracking during drying. While significant advances have been made, it is still difficult to generally explain all patterns of behaviour. This paper presents a new framework for modelling volumetric response of unsaturated soils with emphasis on compacted soils. The framework uses void ratio (e), moisture ratio ([e.sub.w]), and net stress (p) as the main constitutive variables and suction as a dependent variable. This choice of [e.sub.w] as a main constitutive variable is theoretically sound and is more attractive than the use of suction, which is relatively difficult to measure and displays significant hysteresis during drying and wetting. The framework incorporates the well-known compaction curve making it easily applicable to practical situations. Within the overall e-[e.sub.w]-p space, the operative space is constrained by three main surfaces; namely, loading-wetting state boundary surface, tensile failure surface, and the saturated plane. The conceptual basis for these state surfaces is described and the framework is qualitatively validated against observed behaviour of compacted soils. Key words: unsaturated soils, moisture content, soil compaction, void ratio, constitutive modelling. Le comportement volumetrique est une consideration fondamentale lors de la modelisation constitutive des sols non satures. La complexite est plus grande que lorsque le sol est sature puisque les sols non satures presentent une variete de comportements, comme le gonflement et l'effondrement durant le mouillage, et le retrait et la fissuration lors du sechage. Malgre le fait que plusieurs avancees significatives ont ete realisees, il est encore difficile d'expliquer de facon generale tous les types de comportement. Cet article presente une nouvelle approche pour la modelisation du comportement volumetrique des sols non satures, avec une emphase sur les sols compactes. L'approche utilise l'indice des vides (e), le ratio d'humidite ([e.sub.w]) et la contrainte nette (p) en tant de variables constitutives principales, et la succion en tant que variable dependante. Ce choix de [e.sub.w] comme variable constitutive principale est justifiable de maniere theorique et est plus simple que d'utiliser la succion, puisque la succion est relativement difficile a mesurer et demontre des effets d'hysteresis importants en mouillage et en sechage. Cette approche integre la courbe de compaction bien connue, ce qui la rend applicable aux situations pratiques. A l'interieur de l'espace e-[e.sub.w]-p, l'espace operatoire est contraint par trois surfaces principales: la surface frontiere de l'etat en mouillage-sechage, la surface de rupture en tension, et le plan sature. La base conceptuelle de ces trois surfaces est decrite et l'approche est validee qualitativement a l'aide d'observations du comportement de sols compactes. Mots-cles: sols non satures, teneur en eau, compaction du sol, indice des vides, modelisation constitutive. [Traduit par la Redaction], Introduction A large portion of geotechnical works is associated with unsaturated soil either as compacted fills or natural soil above the water table. In contrast to saturated soils below the [...]

The active earth pressure used in the design of gravity walls is calculated based on the internal friction angle of the retained soil or backfill. However, the friction angle of a soil changes during the deformation process. For drained loading, the mobilized friction angle varies between the peak and critical-state friction angles, depending on the level of shear strain in the retained soil. Consequently, there is not a single value of friction angle for the retained soil mass, and the active earth pressure coefficient changes as the wall moves away from the backfill and plastic shear strains in the backfill increase. In this paper, the finite element method is used to study the evolution of the active earth pressure behind a gravity retaining wall, as well as the shear patterns developing in the backfill and foundation soil. The analyses relied on use of a two-surface plasticity constitutive model for sands, which is based on critical-state soil mechanics. Key words: finite elements, plasticity, retaining walls, sands. La pression active des terres utilisee dans la conception des murs gravitaires est calculee a partir de l'angle de friction interne du sol ou du remblai retenu. Cependant, l'angle de friction d'un sol change durant le processus de deformation. Dans le cas d'un chargement draine, l'angle de friction mobilise varie entre l'angle de friction au pic et celui a l'etat critique, dependant du niveau de deformation en cisaillement dans le sol retenu. En consequence, il n'y a pas de valeur unique d' angle de friction pour une masse de sol retenue, et le coefficient de pression active des terres varie a mesure que le mur se separe du remblai et que les deformations plastiques en cisaillement augmentent dans le remblai. Dans cet article, la methode par elements finis est utilisee pour etudier l'evolution de la pression active des terres derriere un mur de soutenement gravitaire, ainsi que les patrons de cisaillement qui se developpent dans le remblai et dans le sol de fondation. Les analyses sont realisees a l' aide d' un modele constitutif de plasticite a deux surfaces pour des sables, qui est base sur la mecanique de l' etat critique des sols. Mots-cles : elements finis, plasticite, murs de soutenement, sables. [Traduit par la Redaction], Introduction The active earth pressure acting on the back of a retaining wall controls its design. The active earth pressure is expressed as the product of the vertical effective stress [...]

This paper presents 9 years of measured pore pressures from eight piezometers installed in a marine clay slope in southeast Norway and the results of a two-dimensional finite element (FE) analysis performed to evaluate infiltration effects on groundwater flow and pore-pressure response. The assumed time-varying boundary flux record used in the analysis to simulate infiltration considers the effects of temperature, snow depth, land-use practices, and soil hydraulic conductivity. The pore-pressure records and analyses show that: (i) the maximum pore pressure reached is nearly the same each year; (ii) this maximum corresponds to a groundwater surface at or near the ground surface; (iii) the two-dimensional groundwater model used for the analysis is adequate for understanding of factors affecting infiltration, seepage patterns, and pore-pressure variations; and (iv) it is difficult to precisely model all aspects of the observed pore-pressure variations. Key words: marine clay, quick clay, landslide, slope stability, precipitation, pore-pressure measurements. L'article presente des resultats de 9 ans de mesures de pression interstitielle prises sur huit piezometres installes dans une pente d'argile marine au sud-est de la Norvege et les resultats d'une analyse par elements finis en deux dimensions effectuee pour evaluer les effets de l'infiltration sur l'ecoulement de l'eau souterraine et sur les pressions interstitielles. Les estimations utilisees comme frontiere de flux variable selon le temps qui ont servi dans l'analyse pour simuler l'infiltration considerent les effets de la temperature, de la profondeur de la neige, des utilisations du territoire et de la conductivite hydraulique du sol. Les donnees de pressions interstitielles et les analyses montrent que : La pression interstitielle maximale est a peu pres la meme chaque annee; Ce maximum correspond a une nappe phreatique a la surface ou pres de la surface; Le modele a deux dimensions utilise pour l'analyse de l'eau souterraine est adequat pour comprendre les facteurs qui affectent l'infiltration, les exfiltrations et les variations de pressions interstitielles; Il est difficile de modeliser avec precision tous les aspects des variations de pressions interstitielles observees. Mots-cles : argile marine, argile sensible, glissement de terrain, stabilite de pente, precipitations, mesures de pression interstitielle. [Traduit par la Redaction], Introduction From October 1969 to August 1978, data was recorded for eight piezometers installed in marine clay slopes at a study site at the Lodding farm in the Romerike district [...]

Ghosh's note enlarges the range of applicability of the pseudo-dynamic method, which Choudhury and Nimbalkar (2006) had already enlarged with the introduction of the vertical component of the seismic force [...]

Three series of 10 piles each were installed in two different locations. The lengths of the piles varied from 2 to 6 m and the diameters were 14 and 25 cm. The piles were constructed above the groundwater table using continuous flight augers and the concrete was placed by gravity free fall. The piles were tested to failure in axial uplift and the load--displacement relations were recorded. The results from the tests have been compared with theoretical values based on current design practice and the method proposed by Fleming et al. seems to produce the best match with the test results. Key words: bored piles, drilled shafts, sand, uplift, earth pressure coefficient, unit skin friction. Trois series de 10 pieux chacune ont ete installees dans deux differentes localisations. Les longueurs des pieux ont varie de 2 a 6 m et les diametres etaient de 14 et 25 cm. Les pieux ont ete construits au-dessus de la nappe d'eau souterraine en utilisant des tarieres a pas continu et le beton a ete place par gravite en chute libre. Les pieux ont ete testes a la rupture en arrachement axial et nous avons enregistre les relations charge--deplacement. Les resultats des essais ont ete compares avec les valeurs theoriques basees sur la pratique courante de conception, et la methode proposee par Fleming et al. semble produire la meilleure adequation avec les resultats des essais. Mots-cles: pieux fores, puits fores, sable, arrachement, coefficient de pression des terres, frottement par unite de surface du fut., Introduction Bored piles, also known as drilled shafts, often provide an economical alternative to other types of foundations (e.g., driven piles). They are used advantageously in cases where only a [...]

The use of Rankine's method is inappropriate for calculating active thrusts in cantilever retaining walls with a short heel because the thrust wedge is interrupted by the wall backface. The use of Coulomb's approach is preferable, but at present only numerical solutions have been proposed to solve the problem. This paper presents an analytical solution, based on Coulomb's approach, for evaluating the active thrust on cantilever walls with a short heel subjected to homogeneous backfill with a regular topographic profile and without pore pressure. The solution is given by an algorithm where two equations, one quadratic and the other cubic, are solved in turn, in an iterative procedure that converges rapidly. The distribution of lateral pressure and the position of the point of application of the thrust are also given in analytical terms. Key words: active earth force, cantilever walls, lateral pressure, active condition. Dans le cas des murs de soutenement cantilever avec un court pied arriere, l'utilisation de la methode de Rankine pour le calcul des poussees est inadequate parce que le coin de pression est coupe par la face arriere du mur. L'utilisation de la methode de Coulomb est preferable, mais jusqu'a maintenant, on a propose seulement des solutions numeriques pour resoudre le probleme. Cet article presente une solution analytique basee sur l'approche de Coulomb pour evaluer la poussee sur les murs cantilever avec un pied court, retenant un remblai homogene avec un profil topographique regulier et sans pression interstitielle. La solution est donnee par un algorithme ou on resout a tour de role deux equations, une quadratique et l'autre cubique, dans une procedure iterative qui converge rapidement. La distribution de la pression laterale et la position du point d'application de la pression sont egalement donnees en termes analytiques. Mots-cles : force de poussee des terres, murs cantilever, pression laterale, condition de poussee. [Traduit par la Redaction], Introduction Thrusts on cantilever retaining walls are generally calculated using Rankine's method (Rankine 1857). This method is based on the assumption that, due to the wall movement and the consequent [...]

Few studies have been carried out on the bearing capacity of soils for crawler cranes. Directly applying the bearing capacity equations used for shallow foundations to cranes often leads to conservative design. The total settlement is of less concern for cranes than for buildings, and cranes can normally tolerate larger differential settlements. Computer simulation and field studies have been carried out to study the allowable bearing capacity of soils for cranes. Equations modified from the traditional method to calculate the bearing capacity for shallow foundations have been proposed. In general, it was found that the bearing capacity for crawler cranes could be increased by as much as 50% from that for foundations. This depends on the soil type, crane, and mat configuration. A design procedure in evaluating foundation support for crawler cranes is also proposed. Key words: soil bearing capacity, crawler crane, crane track pressure. Il y a eu peu d'etudes realisees sur la capacite portante des sols pour les grues a chenilles. L'application directe aux grues des equations de capacite portante utilisees pour des fondations superficielles conduit souvent a une conception conservatrice. Le tassement total presente moins de souci pour des grues que pour des batiments, et les grues peuvent normalement tolerer des tassements differentiels plus importants. Une simulation par ordinateur et des etudes sur le terrain ont ete realisees pour etudier la capacite portante admissible des sols pour des grues. On a propose des equations modifiees par rapport a la methode traditionnelle pour calculer la capacite portante pour les fondations superficielles. En general, on a trouve que la capacite portante pour les grues a chenilles pouvait etre augmentee par autant que 50 % par rapport a celle pour les fondations. Ceci depend du type de sol et de grue, et de la configuration du tapis. On propose aussi une procedure de conception pour evaluer la fondation portante pour des grues a chenilles. Mots-cles : capacite portante des sols, grue a chenilles, pression sur la chenille de la grue. [Traduit par la Redaction], Introduction Soil bearing capacity for shallow footing foundations has been studied extensively from the 1920s to the 1970s. It is generally accepted that the two criteria that govern the allowable [...]

Abstract: In this study, the swell pressure versus soil suction behaviour was investigated using artificial neural networks (ANNs). To achieve this, the results of the total suction measurements using thermocouple [...]

Abstract: An oedometer instrumented to measure horizontal pressure was used to examine the behavior of the coefficient of earth pressure at rest, [K.sub.o], of clean sands subjected to vertical vibration. [...]

Abstract: In this study, a method is proposed on the basis of the diffuse double layer theory to determine the compressibility of clays for one-dimensional conditions for vertical pressures far [...]

Introduction The authors are to be congratulated on presenting four solutions for the average excess pore pressures of axisymmetric and plane strain unit cells; in these solutions, two solutions are [...]

The author has to be commended for obtaining an elegant solution to the problem of the Coulomb active thrust exerted by a cohesionless backfill and a vertical line load. This [...]

The writers are grateful for the interest and the feedback provided by the discussers. Responses to their concerns are addressed as follows. Applied vacuum pressure for the equivalent plane strain [...]

The author is very grateful to Professor Silvestri for the interest shown in his paper and for the contribution given to the solution of the problem throughout his discussion. It [...]