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Hydraulic contact pressure cells were installed on the abutments of an integral abutment bridge to monitor changes in earth pressure over an extended period of time. The accuracy of field data from such instruments is affected by a number of factors. In particular, temperature changes are one of the key factors that can influence earth pressure measurements. Thermal calibration factors supplied by manufacturers of such cells tend to only account for the effect of temperature on the pressure transducer, rather than on the instrument as a whole. Therefore, in an effort to quantify the effect of temperature on data collected from the contact pressure cells installed on the integral abutment bridge, laboratory thermal calibration of these sensors was undertaken. Construction-related time constraints precluded extensive testing of the instruments installed in the field; however, extensive tests were conducted on an identical contact and earth pressure cell. Laboratory thermal calibration tests were conducted on the sensors for an unloaded, unconfined condition and with sensors confined in soil and loaded with uniform pressure. All tests were conducted in a cold room where temperatures could be controlled over a wide range. Results indicate that both temperature and applied pressure affect the performance of hydraulic pressure cells. Thermal correction factors were developed from linear-regression analysis of the unloaded, unconfined test data; however, application of these factors to the loaded, confined test data was found to account for only a portion of the pressure variation, with the remaining variation still being significant. Similar correction factors by linear regression analysis could not be developed from the loaded, confined pressure test data. However, when considering the range of temperatures experienced by the pressure cells installed on the integral abutment bridge, it was concluded in a 2013 study by the authors that the thermal pressure variations present in the field data should not exceed ±10 kPa. The results of this research demonstrate the need for extensive laboratory calibration of these types of pressure cells for proper interpretation of field data. [ABSTRACT FROM AUTHOR]

Integral abutment bridges accommodate thermal superstructure movements through flexible foundations rather than expansion joints. While these structures are a common alternative to conventional design, the literature on measured field stresses in piles supporting integral abutments appears to be quite limited. Therefore, field data from strain gauges installed on the abutment foundation piles of a 76 m long; two-span integral abutment bridge are the focus of this paper. Axial load, weak- and strong-axis bending moments of the foundation piles, as well as abutment movement and backfill response, are presented and discussed. Results indicate that the abutment foundation piles are bending in double curvature about the weak axis, as a result of thermal bridge movements, and bending also about the strong axis due to tilting of the abutments. A simple subgrade modulus approach is used to show its applicability in predicting behaviour under lateral loading. In the past, much emphasis has been placed on the lateral displacements of piles and less on variations of axial load. In this paper, a new hypothesis, which offers insight into the mechanisms behind the observed thermal variations in axial load, is proposed and assessed. The data from the field monitoring are also compared with the limited data reported in the literature. [ABSTRACT FROM AUTHOR]

Integral abutment bridges have become a successful alternative to the traditional design procedure of using expansion joints to balance the thermal movements of bridge structures. However, there are many design and detailing variations, and uncertainties exist about the soil–structure interaction of the integral abutments. Therefore, field data from pressure cells installed behind the abutments of a 76 m long, two-span, pile-supported integral abutment bridge are the focus of this paper. The data on external displacements of the abutments are also reported. The applicability of using common theoretical passive earth pressure coefficients is assessed and it appears that the traditional methods of Coulomb and Rankine are not the best approach for predicting the earth pressure envelope. Additionally, over the monitoring period of three years, it was found that a definite conclusion regarding the ratcheting of lateral earth pressure could not be established for this bridge site. Finally, comparisons to earth pressures measured at other field studies indicate variability in the earth pressure distribution, magnitude, and behaviour over time, as these are dependent on several factors distinctive to each bridge site. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Although several induced trench field instrumentations have been reported in the literature, none have been for twin culverts. This paper describes a field instrumentation of twin 3660 mm inside diameter concrete culverts installed in an induced trench under 21.7 m of fill. Earth pressures were measured at the crown, shoulder, springline, haunch, and invert locations. Average earth pressures measured at the crown and springline were 0.67 and 0.32 times the overburden, respectively. Due to the large culvert size, proper compaction in the haunch regions was not achieved and the bedding was lightly compacted for constructability reasons. These factors resulted in high earth pressures at the inverts (greater than approximately 1400 kPa) and low pressures at the haunches (32-165 kPa). Numerical modelling was used to determine a vertical earth load of 0.87 times the soil prism load. The twin induced trench condition resulted in vertical earth loads 6% higher and 30% lower than the single induced trench and twin positive projecting conditions, respectively. The induced trench method therefore appears to be a viable installation option for large-diameter twin culverts, provided that issues related to bedding and constructability are addressed. [ABSTRACT FROM AUTHOR]

Although twin culverts are often preferred for watercourse crossing, little is known about the earth pressures they experience under high embankments. Centrifuge test results have been used in this research to verify a numerical model used to evaluate culvert spacing and compressible zone geometry for twin positive projecting and induced trench box culverts. Lower pressures were calculated for twin positive projecting culverts than for a single culvert. For the induced trench case, one compressible zone spanning both culverts was the preferred geometry for culverts spaced at 0.5Bc and 1.0Bc (where Bc is the culvert width), while two zones 1.2Bc wide were found to be optimal for 1.5Bc spacing. The twin configurations generally resulted in slightly higher vertical and lower lateral earth pressures than a single culvert configuration. The base contact pressures were 25%-76% greater than the top pressure plus dead load because of shear stresses mobilized along the sidewalls; however, they were 41%-47% lower than the pressures for positive projecting configurations. The maximum bending moments calculated for the induced trench culverts were 54%-59% lower than for the positive projecting ones. Induced trench construction therefore appears to be viable for twin box culverts, provided that frictional forces along the sidewalls are taken into account. Les ponceaux doubles sont souvent utilisés pour les traverses de cours d'eau, malgré le fait qu'il y ait peu de connaissances sur les pressions des terres qu'ils subissent sous des remblais épais. Des résultats d'essais en centrifuge ont été utilisés dans cette étude afin de vérifier un modèle numérique servant à évaluer l'espacement des ponceaux et la géométrie de la zone compressible pour les ponceaux doubles à projection positive et pour les ponceaux rectangulaires avec tranchée induite. Des pressions plus faibles ont été calculées pour les ponceaux doubles à projection positive comparativement aux ponceaux simples. Pour le cas de tranchées induites, une seule zone compressible couvrant les deux ponceaux correspond à la géométrie préférable pour des ponceaux espacés de 0,5Bc et 1,0Bc (où Bc est la largeur du ponceau), tandis que deux zones de 1,2Bc de largeur représentent la configuration optimale pour un espacement de 1,5Bc. Les configurations doubles ont généralement des pressions des terres verticales un peu plus élevées et des pressions latérales plus faibles qu'une configuration à un seul ponceau. Les pressions de contact à la base sont plus élevées par un facteur de 25 à 76 % par rapport aux pressions sur le dessus en plus de la charge du ponceau, puisque les contraintes de cisaillement sont mobilisées le long des murs de côté; cependant elles sont 41 à 47 % plus faibles que les pressions exercées dans le cas de configurations à projection positive. Les moments de torsion maximums calculés pour les ponceaux avec tranchée induite sont de 54 à 59 % plus faibles que pour les configurations à projection positive. La construction de tranchées induites semble alors être appropriée pour les ponceaux rectangulaires doubles lorsque les forces de friction le long des murs de côté sont considérées. [ABSTRACT FROM AUTHOR]

Induced trench construction is routinely used for circular conduits, but its application for box culverts is less common. To understand the complex soil–structure interaction issues related to the design of induced trench box culverts, centrifuge tests were performed to measure earth pressures on a model box culvert installed in several induced trench configurations. These tests were modelled with FLAC and good agreement was achieved. A parametric study performed with FLAC identified a preferred compressible zone geometry having a width of 1.2 times the culvert width and a thickness of 0.5 times the culvert height. For this geometry, the earth pressure on the top was 0.28 times the overburden, the lateral earth pressure on the sides was 0.47 times the mid-height overburden, and the contact pressure at the base was 0.73 times the overburden plus the pressure from the dead load of the culvert. The average base contact pressures for the induced trench geometry were 35% lower than those for the corresponding positive projecting case. The induced trench method, therefore, appears to be a viable option for box culverts installed under high embankments. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the results of shear resistance tests conducted on geofoam blocks with no connection, blocks connected with barbed connector plates, and blocks connected with polyurethane adhesive. In the first phase, tests were completed in a large direct shear box (430mm L×280mm W) under normal pressures of 14.8kPa, 29.6kPa, and 74.1kPa. In phase II, tests were conducted on 1200mm L×600mm W specimens using a computer controlled actuator under normal pressures of 9.3kPa, 18.1kPa and 26.9kPa. The measured values of the coefficient of friction between blocks were found to be consistent with the values reported in the literature and conservative in terms of commonly used design values. The test results show that the presence of barbed connector plates did not provide additional interface shear resistance; however polyurethane adhesive was successful in bonding the blocks together thus virtually eliminating horizontal sliding between the blocks. Blocks connected with barbed connector plates subject to repeated loading showed signs of decreased shear resistance during reloading, but did reach the peak shear resistance measured during initial loading. [Copyright &y& Elsevier]

The field performance of an induced trench installation is compared to the results of centrifuge testing and numerical modelling. The measured vertical pressure at the crown of the pipe in the field ranged from 0.24 to 0.36 times the overburden pressure. The horizontal earth pressures measured in the field at the springline level determined a coefficient of lateral earth pressure between 0.39 and 0.49. The culvert was monitored over a period of 2 years following completion of embankment construction indicating no measurable changes in earth pressures and deformations. A model box culvert simulating the prototype height of soil cover, the pipe width, and the thickness of the compressible layer was tested using a geotechnical centrifuge. The prototype structure was also evaluated using numerical modelling to predict full earth pressure distribution and deformations. A comparison of field data, centrifuge testing, and numerical modelling shows that the Marston–Spangler theory used in designing induced trench culverts is conservative. The theory however, does not address or predict the nonuniform pressures on the top, sides, or bottom of the pipe, and therefore numerical analysis should be used to estimate the complete pressure distribution. [ABSTRACT FROM AUTHOR]

Arching theory predicts a significant reduction in earth pressures behind retaining walls of narrow backfill width. An extensive series of centrifuge tests has been performed to evaluate the use of flexible subminiature pressure cells in the centrifuge environment and their subsequent use to measure lateral earth pressures behind retaining walls of narrow backfill width. Although the flexible earth pressure cells exhibit hysteresis and nonlinear calibration behaviour, the extensive calibration studies indicate that stiff diaphragm type earth pressure cells may be used with replicate models to measure earth pressures. Measurements of lateral pressures acting on the unyielding model retaining walls show good agreement with Janssen's arching theory. Tests on backfills bounded by vertical planes of dissimilar frictional characteristics indicate arching theory with an average interface friction angle provides a reasonable estimate of lateral earth pressures.Key words: fascia retaining walls, silos, earth pressures, pressure cells, centrifuge modelling.La théorie d'arc-boutement prédit une réduction significative des pressions des terres à l'arrière des murs soutenant un remblai de faible largeur. Une série importante d'essais au centrifuge a été réalisée pour évaluer l'utilisation de cellules de pression miniatures flexibles dans l'environnement du centrifuge et leur utilisation subséquente pour mesurer les pressions latérales des terres à l'arrière de murs soutenant des remblais de faible largeur. Quoique les cellules flexibles de pression des terres montrent de l'hystérèse et un comportement non linéaire en calibrage, les études nombreuses de calibrage indiquent que les cellules de pression des terres avec diaphragme rigide peuvent être utilisées au moyen de reproductions de modèles pour mesurer les pressions des terres. Des mesures de pressions latérales agissant sur des modèles de murs de soutènement rigides concordent bien avec la théorie d'arc-boutement de Janssen. Des essais sur des remblais avec des plans verticaux de caractéristiques de frottement non similaires aux frontières indiquent que la théorie d'arc-boutement avec un angle de frottement moyen à l'interface fournit une estimation raisonnable des pressions des terres.Mots clés : murs de soutènement en panneau, silos, pressions des terres, cellules de pression, modélisation par centrifuge.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The article mentions people that the editors would like to thank for their assistance in the creation of the journal.

Provides information on the volume of manuscripts sent to the "Canadian Geotechnical Journal" to be reviewed. Affiliation of the journal with the Canadian Geotechnical Society; Reason behind the increase in the workload of Associate Editors of the journal; List of reviewers who contributed to the journal.

In this paper, the stabilisation of a 60 m-high natural slope located in Fujian Province in southeast China is analysed using finite-element and limit equilibrium methods. The strength reduction finite-element analysis was able to capture the behaviour of the slope before stabilisation and its performance after stabilisation. The factors of safety obtained with the two different approaches are compared and discussed in this paper. Deformation analysis was also conducted to investigate the serviceability of the slope during the stabilisation construction activities. The results show that the combination of slope flattening and ground anchors was able to provide the required stabilisation while satisfying serviceability requirements, as the deformations at the crest and toe of the slope were within tolerable limits. [ABSTRACT FROM AUTHOR]

The article presents information on the "Canadian Geotechnical Journal." Its first issue was published in September 1963. The journal was described as a significant regional development in the field of soil mechanics and foundation engineering. The evolution of the journal is discussed. The journal received strong support from the Canadian Geotechnical Society.

Presents a note of appreciation to the people who contributed to the volume 41, 2004 issue of the "Canadian Geotechnical Journal ."

Acknowledges the efforts and work done by the previous editorial staff of the "Canadian Geotechnical Journal." Appreciation of the guidance and assistance offered by Dennis Baker, previous editor of the periodical, during the changeover of responsibilities; Contributions of the previous team of associate editors to the journal, which are greatly appreciated; Gratefulness for the staff of the NRC Research Press for their help during the transition.

The use of deep soil mixing technologies has become increasingly common in North America following its widespread development and adoption in Japan and Scandinavia. This research project considered how design of soft soils stabilised with deep soil mixing may be optimised to satisfy global slope stability requirements to assist the construction of large reclaimed land projects. The land reclamation case that was studied in the present paper deals with raising the elevation of a terrestrial area above a tidal or flood zone, where the water table is close or at the original grade. In this work, the effect of several key design parameters on the global factor of safety against slope failure for a land reclamation project was studied using limit equilibrium slope stability analyses. The parametric analyses considered design parameters, including the thickness of the soft soil layer, as well as the strength, width and location of a stabilised soil zone. The purpose of this work is to provide guidelines for the preliminary design of ground improvements for future land reclamation projects using deep soil mixing methods by identifying design parameters that have the most significant impact on the global factor of safety. [ABSTRACT FROM AUTHOR]

The instrumentation, construction, and field performance of a full-scale test embankment constructed on a soft compressible organic clayey silt is described. The construction sequence, the observed vertical and horizontal displacements, and the pore pressure response are presented. The embankment behaved elastically up to a thickness of about 3.65 m. The settlement and heave responses suggested that the embankment approached failure at a thickness of about 6.1 m and a corresponding net height of 5.4 m. The failure was gradual and of a viscoplastic type, and no classical-type abrupt failure was encountered during the construction of this embankment. The height to which the embankment could be constructed was lower than the 7–11.4 m range expected from conventional two-dimensional (2D) limit equilibrium analysis based on vane strength data. This, coupled with the pore pressure response, suggests that a combination of progressive failure and the influence of the adjacent reinforced section constructed to failure may have been significant factors affecting the performance of this embankment. Thus, the data reported in this paper can be used as a test case for developing three- dimensional (3D) analysis methods wherein the constitutive model can be truly tested for 3D conditions involving the interaction between embankment sections that are constructed under different conditions.Key words: embankment, field behaviour, stability, deformations, pore pressures.On décrit l'instrumentation, la construction et le comportement sur le terrain d'un remblai d'essai construit sur un silt argileux organique mou et compressible. Cet article présente le cheminement de la construction, les déplacements verticaux et horizontaux observés, de même que la réponse de la pression interstitielle. Le remblai s'est comporté en mode élastique jusqu'à une épaisseur d'environ 3,65 m. Les comportements en tassement et en soulèvement ont indiqué que le remblai s'approchait de la rupture à une épaisseur d'environ 6,1 m, soit une hauteur nette de 5,4 m. La rupture a été graduelle et de type viscoplastique; il ne s'est pas produit de rupture abrupte de type classique durant la construction de ce remblai. La hauteur à laquelle le remblai aurait pu être construit a été plus faible que la plage de 7 à 11,4 m donnée par l'analyse d'équilibre limite bidimensionnelle conventionnelle utilisant les données de résistance au scissomètre. Cette observation combinée avec la réaction de la pression interstitielle indique qu'une combinaison de rupture progressive et de l'influence de la section adjacente armée construite jusqu'à la rupture peuvent avoir été des facteurs significatifs qui ont affecté le comportement de ce remblai. Ainsi, les données présentées dans cet article peuvent être utilisées comme un cas d'essai typique pour développer des méthodes d'analyse tridimensionnelle dans lesquelles le modèle de comportement peut vraiment être testé pour des conditions 3D impliquant l'interaction entre des sections de remblais qui sont construites dans des conditions différentes.Mots clés : remblai, comportement en nature, stabilité, déformation, pressions interstitielles.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Induced trench construction is commonly used to reduce earth pressures on rigid circular and box culverts. Most of the reported literature pertains to the performance of induced trench culverts during construction and shortly after construction. This paper addresses the post-construction performance of induced trench culverts. First, results of field inspection reports are presented as an indirect assessment of performance of 90 induced trench culverts installed in New Brunswick that have been in service for up to 24 years. Second, earth pressure measurements are presented from three case studies where prototype installations were monitored over periods ranging from 4 to 9 years. The case studies presented include a single circular culvert, a cast-in-place double-cell box culvert, and a twin circular culvert installation. The fill heights above the instrumented structures varied from 19 to 25 m. All the available data from both the field inspections and earth pressure measurements indicate that the culverts installed in induced trenches are performing in a satisfactory manner. [ABSTRACT FROM AUTHOR]