bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-dependent stress–strain behaviour due to viscous properties of geogrid reinforcement
Authors: Hirakawa D. , Kongkitkul W. , Tatsuoka F. , Uchimura T.
Published: October 2009

A series of conventional and unconventional tensile tests were performed on six types of geosynthetic reinforcement to evaluate their viscous properties. It is shown that the isochronous model, according to which the load (or the stress) is a unique function of instantaneous strain and elapsed time, is unable to explain the major viscous aspects of the test results. In particular the model is unable to predict the stress–strain behaviour and rupture strength observed after loading is restarted at a constant strain rate following a creep loading or stress relaxation stage. It is argued that the widely prevailing concept that creep is a degrading phenomenon requiring the design strength to be reduced with an increase in the design lifetime is not realistic under typical field conditions where the stress–strain property does not deteriorate noticeably with time. It is also argued that this concept stems from the isochronous model. A non-linear three-component model is proposed to simulate the viscous aspects of the strength and deformation characteristics of the tested geosynthetic reinforcements. It is shown that this rheology model can simulate very well the experimental results obtained by the present study.
Design and behaviour of geosynthetic-reinforced soil walls constructed on yielding foundations
Authors: Skinner G. D. , Rowe R. K.
Published: October 2009

The short- and long-term behaviour of a 6 m high segmental block-faced geosynthetic-reinforced retaining wall constructed on a rigid base and two 10 m thick clay foundations (one relatively inviscous and one viscoplastic) were numerically investigated to assess the effect of yielding in the foundation deposit on the internal and external stability of the wall. The influence of the rate of loading on the undrained shear strength of the viscoplastic foundation clay deposit is examined. The overall short- and long-term behaviour of the reinforced soil wall, including reinforcement strains and deformations, are discussed and compared with the expected design values. It is shown that the viscoplastic nature of some clayey soils can cause a decrease in the undrained shear strength with time by as much as 20% and increase the reinforcement strains by as much as 45% relative to expected design values.
Retention performance of geotextile containers confining geomaterials
Authors: Kutay M. E. , Aydilek A. H.
Published: October 2009

The design of geotextile containers for dewatering applications typically requires hydraulic compatibility between the geotextile and the confined fill material. Ideally, a geotextile container must successfully retain the solid phase of the fill material and must not be clogged during the dewatering process. This becomes difficult to achieve when the fill material is fine grained and the pore openings are large, such as with traditional geotextile containers. Fly ash and bottom-sea dredged sediments are some of the fine-grained geomaterials that exhibit behaviour that is different from that of regular soils because of differences in their particle structure and chemical composition. In most cases, existing geotextile filter selection criteria are not directly applicable to these unusual geomaterials: therefore an evaluation of the filtration performance of such materials is necessary. A laboratory testing programme was conducted to evaluate the retention performance of geotextiles with fly ash and bottom-sea dredged sediments. The results indicated that both fly ash and dredged sediments could be successfully retained by a variety of woven geotextiles and nonwoven/woven combinations. Results also showed that use of a double-layer geotextile system, rather than a single woven geotextile, significantly increased the retention capacity. Geotextile hydraulic properties such as permittivity and the apparent opening size had little effect on dewatering efficiency; however, the same properties directly influence the retention performance. Additionally, a relatively low initial water content of slurry and the filter cake formed at the soil/geotextile interface promote the retention performance. Geotextile apparent opening size-to-soil particle size ratios in the existing retention criteria did not always accurately predict the observed performance. Therefore a parametric study is needed to evaluate various ratios and to find the most discriminating ratio for retention performance.
Volatile organic compound diffusion and sorption coefficients for a needle-punched GCL
Authors: Lake C. B. , Rowe R. K.
Published: October 2009

Test apparatus designed to examine volatile organic compound (VOC) diffusion through geosynthetic clay liners (GCLs) are described, together with procedures for evaluating the relevant diffusion and sorption parameters. Test results show that the rate of contaminant migration proceeded through the hydrated GCL in the decreasing order of DCM and DCA > benzene > TCE and toluene. This was attributed to varying degrees of sorption of DCA, benzene, TCE and toluene to the geotextile component of the GCL as well as to the bentonite present in the GCL. Diffusion coefficients deduced from VOC diffusion testing conducted on the GCLs at confining pressures lower than approximately 10 kPa range from 2 × 10–10 m2/s to 3 × 10–10 m2/s. This is generally lower than those reported in the literature for compacted clay liner materials. Assessments of the environmental protection afforded by a landfill liner require that all underlying soil and geosynthetics components be considered in landfill contaminant migration assessments. The results in this paper provide some of the first published data for laboratory GCL diffusion and sorption coefficients, required to perform contaminant migration assessments for five VOC contaminants commonly found in municipal solid waste leachate.
Assessment of equivalence of composite liners
Authors: Rowe R. K. , Brachman R. W. I.
Published: October 2009

The equivalence of composite liners involving a geomembrane (GM) and a compacted clay liner (CCL) to alternative composite liners with a geomembrane, geosynthetic clay liner (GCL) and attenuation layer (AL) is assessed in terms of the contaminant impact occurring in a receptor aquifer. Calculations of contaminant impact of dichloromethane, benzene and chloride through GM/CCL/AL and GM/GCL/AL composite liners are reported for a hypothetical municipal solid waste landfill. The geomembrane in conjunction with either the CCL or GCL is very effective at controlling leakage such that diffusion essentially dominates the impact on the aquifer for the service life of the geomembrane. The geomembrane itself offers little resistance to diffusion of dichloromethane and benzene, and consequently the CCL or GCL and AL (of suitable thickness) are required to protect the aquifer. In contrast, the geomembrane acts as an excellent diffusion barrier to chloride over its service life. For the cases and parameters examined, the GM/GCL/AL liners were found to provide the same or even greater environmental protection to the underlying aquifer relative to GM/CCL/AL liners provided the total thickness of the liner system with the GCL was the same as that with the CCL. This can be achieved by having a thicker attenuation layer with the GM/GCL liners. Chloride impacted on the aquifer only after the service life of the geomembrane had been reached, after which contaminant transport was controlled by advection though the soil component of the liner for the cases examined.
Occurrence and effect of bentonite migration in geosynthetic clay liners
Authors: Stark T. D. , Choi H. , Akhtarshad R.
Published: October 2009

Since the introduction of geosynthetic clay liners (GCLs) to waste containment facilities, one of the major concerns about their use has been the hydraulic equivalence to a compacted clay liner as required by regulations. Laboratory test results and more recently field observations show that the thickness, or mass per unit area, of hydrated bentonite in a GCL can decrease under normal stress, especially around zones of stress concentration or non-uniform stresses, such as a rock or roughness in the subgrade, a leachate sump, or wrinkles in an overlying geomembrane. This paper presents field case histories that confirm the laboratory observations of bentonite migration and the effect of bentonite migration on hydraulic equivalence and contaminant transport through a GCL. Finally, the paper presents suggestions for protecting hydrated bentonite from stress concentrations and reducing contaminant transport through a GCL.
Liquid migration in an encapsulated bentonite layer due to geomembrane defects
Authors: Giroud J. P. , Daniel D. E.
Published: October 2009

In some applications of geosynthetic clay liners (GCLs), the bentonite layer component of the GCL is encapsulated between two geomembranes. One of the benefits of this configuration is to decrease the risk of shear strength decrease due to bentonite hydration. The liner thus formed is typically used to contain a liquid, such as water or leachate. If there is a defect in the upper geomembrane, some of the liquid initially contained above the upper geomembrane migrates into the bentonite. Similarly, if there is a defect in the lower geomembrane, some of the liquid initially contained in the soil underlying the lower geomembrane migrates into the bentonite. The liquid that has migrated into the bentonite then migrates laterally in the bentonite between the two geomembranes. The analyses presented in this paper provide analytical solutions for the one-dimensional and axisymmetrical cases. In each of the two cases, two types of analytical solution are provided: an equation that gives the time required for the hydration front to reach a certain distance from the geomembrane defect, and an equation that gives the rate of liquid migration through the defect. It appears that the time required for the hydration front to reach a relatively small distance (e.g. a few meters) is very long (i.e. of the order of decades). Therefore a very long time is required for the development of a large hydrated area that could significantly impact shear strength. Also, a very long time is required for liquid migrating through a defect in the upper geomembrane to reach a defect in the lower geomembrane, thereby creating a leakage path from the medium overlying the upper geomembrane to the medium underlying the lower geomembrane. The analyses also show that the rate of liquid migration through the upper geomembrane defect is very small compared with the rate of leakage through the same defect in the geomembrane component of a typical composite liner where the soil component is clay or a GCL. The results of these analyses demonstrate the effectiveness of a liner that consists of a layer of bentonite encapsulated between two geomembranes, and provide a method to quantify this effectiveness.
Hydrated area of a bentonite layer encapsulated between two geomembranes
Authors: Giroud J. P. , Thiel R. S. , Kavazanjian E.
Published: October 2009

Hydrated bentonite has a low shear strength, which may adversely impact the stability of structures incorporating geosynthetic clay liners (GCLs). Accordingly, in a growing number of GCL applications, the configuration is such that the bentonite layer is encapsulated between two geomembranes in order to reduce the potential for bentonite hydration. This paper considers an encapsulated bentonite layer formed using GM-GCL panels (i.e. panels consisting of a bentonite layer adhered to a carrier geomembrane). The panels are joined by overlapping at the edges and are overlain by a welded geomembrane. Water can migrate from the underlying soil into the bentonite of the overlaps, flow in the bentonite, and migrate laterally in the bentonite between the two geomembranes. Water is driven from the soil to the bentonite by a head difference that results in great part from the suction at the hydration front. This paper presents an analytical method to evaluate the extent of the hydrated area of the bentonite layer as a function of: time, the initial and hydrated moisture content of the bentonite, the hydraulic conductivity of the bentonite, the overlap width, the distance between overlaps, and the head difference. It is important to know the hydrated area for stability calculations. Numerical applications show that, for typical values of the parameters, it takes many decades to hydrate a significant fraction of the bentonite layer area. The analyses presented in this paper also show that, for typical landfill applications, the hydrated area due to leakage through defects in the upper geomembrane is negligible with respect to the hydrated area resulting from water migrating through the overlaps, assuming that the upper geomembrane is installed using good construction quality assurance practices. Uncertainties associated with the methodology presented herein are discussed, and guidance is provided on evaluation of the shear strength of the encapsulated bentonite layer as a function of the shear strength of the unhydrated bentonite, the shear strength of the hydrated bentonite, and the hydrated area.
An approximate isotropic perfectly plastic solution for compressive strength of geosynthetic-reinforced soil
Authors: Tatsuoka F.
Published: October 2009

A closed-form approximate solution, based on the stress characteristics method, for the compressive strength of a cohesionless soil mass reinforced with multiple horizontally arranged geosynthetic reinforcement layers subjected to vertical load through rigid platens is presented. It is assumed that the stress–strain properties of the backfill are isotropic perfectly plastic, the friction angle at the interface between the backfill and the reinforcement is uniform, and the effects of the weight of the backfill can be ignored. Assuming that the length/height ratio of the respective soil layer, sandwiched by reinforcement layers, is sufficiently large, then several other simplifications are introduced in the numerical procedures. The solution is compared with the results of plane strain compression tests using large specimens of air-dried Toyoura sand reinforced with multiple layers of a polymer geogrid. The equivalent friction angles at the interface between the sand and the geogrid, treated as a platen having a 100% coverage ratio, which were previously back-calculated using a non-linear FEM analysis by the author, were used in the present approximate analysis. It is shown that, with known values of the angle of friction of the backfill and the interface friction angle, the compressive strength of a given reinforced soil mass can be estimated reasonably well.
Two-chambered water-filled geomembrane tubes used as water barriers: experiments and analysis
Authors: Kim M. , Filz G. M. , Plaut R. H.
Published: October 2009

Geomembrane tubes are used to withstand external water in various applications, such as flood control, diversion or impoundment of water, and dewatering work sites (i.e. as cofferdams). The external lateral pressure must be resisted, so that the tube does not roll or slip along the ground. Two techniques involving multi-chambered tubes are examined here. In one, the tube has a perforated internal baffle (diaphragm) to resist deformation and rolling. In the other, two tubes are surrounded by an outer tube (sleeve), and friction between the components helps to stabilize the structure. Experiments are conducted on the latter case, and numerical analysis using the finite difference program FLAC is applied to both cases. Various geometrical and friction properties, internal pressures, and headwater levels are considered. Deflected shapes, tensions, critical headwater levels, and corresponding failure modes are determined. The effects of several parameters are investigated. In the examples treated, the critical headwater levels range up to 90% of the height of the baffle tube and up to 80% of the height of the sleeved dam. These devices can be effective fluid barriers (e.g. in place of sandbags for flood protection) if the headwater levels are not too high.
Les Mesures De Cisaillement Dans Les Laboratoires Français
Authors: Mayer A.
Published: October 2009

Synopsis

Dans cet exposé, l'auteur rappelle rapidement les méthodes de mesure du cisaillement appliquees dans les laboratoires français. I1 passe ensuite à la description des essais faits à I'occasion de la conférence de Londres pour préciser les facteurs qui influent sur le cisaillement. I1 souligne la différence entre essais rapides et essais lents, rappelle la relation entre la pression de consolidation et la cohésion des matériaux reconstitués, et indique que la tension superkielle du liquide interstitiel n'influe pratiquement pas sur la cohésion. I1 donne enfin connaissance d'un dispositif experimental qui a permis, à I'appareil triaxial, d'inverser l'ordre de grandeur des pressions verticale et transversale. Ce dispositif a permis de faire des essais de cisaille- ment pur et de prolonger la courbe intrins&que jusqu'à I'axe des Z et au-delà de celle-ci.

Jusqu'ici les essais n'ont porté que sur l'argile plastique de la région parisienne. D'autres essais suivront, notamment sur des limons, dont les résultats seront publiés ultérieurement.

The methods used in French Laboratories for the measurement of shear strength are briefly outlined. Tests carried out on the occasion of the London conference in order to specify the factors which affect shear strength are described. The difference between rapid and slow tests, and the relationship between the consolidation pressure and the cohesion of reconstituted materials are dis- cussed. The Author indicates that the surface pressure of the interstitial liquid has no practical intluence on the cohesion. An experimental device by means of which it is possible, in the triaxial apparatus, to invert the range of the vertical and transverse pressures is described. This device has enabled tests of the true shear strength to be carried out, and has made it possible to extend the intrinsic curve up to the Z-axis and beyond.

Up to now tests have been carried out only on plastic clay from the Paris region. Other tests will follow, notably on silts, the results of which will be published later.
Foundations at Poole Power Station
Authors: Megaw T. M.
Published: October 2009

Synopsis

Poole power station is sited on tidal mudlands, where stiff clays an; overlain by soft silty clay 10 to 40 feet thick, quite inadequate to carry any heavy loads.

Foundations were either excavated within a steel sheet piled cofferdam, down to stiff clay, or were carried on bearing piles. Access for construction plant was obtained by forming a 5-foot thick chalk crust over a large part of the site.

Measurements were made of pressures from the soft clay, by recording the shortening of steel struts in cofferdams within which the coal wharf was constructed. These are compared with loads calculated from the measured shear strength and cohesion of the soft clay. The Author concludes that the equilibrium shear strength of the clay is a more accurate basis for calculation than is the immediate shear strength.

La centrale electrique de Poole est situé sur un terrain formé par des dépôts de vase amenés par la marée, où les argiles fermes sont recouvertes d'argile alluvionnaire molle variant en épaisseur de 3 à 12 mètres, ne convenant absolument pas pour supporter de fortes charges.

Les fondations furent effectuées soit en faisant des excavations à l'intérieur de coffrages en palplanches descendant jusqu'à l'argile ferme, soit sur pilotis. L'accèsaux travaux de construction fut rendu possible par la formation d'une croûte de calcaire de 1,50 m. d'épaisseur sur la plus grande partie du site.

Les pressions de l'argile molle furent mesurées en enregistrant le raccourcissement des entretoises d'acier dans les coffrages à l'intérieur desquels fut construit la soute à charbon. Ces pressions sont comparées avec les charges calculées d'après la force de cisaillement mesurée et la cohésion de l'argile molle. L'auteur conclut que la force de cisaillement de l'argile en état d'équilibre constitue une base de calcul plus précise que ne l'est la force de cisaillement immédiate.
The Effect Measured of the Rubber Membrane on the Triaxial Compression Strength of Clay Samples
Authors: Henkel D. J. , Gilbert G. D.
Published: October 2009

Synopsis

In the undrained triaxial compression test the rubber membranes enclosing the specimens give rise to an apparent increase in strength. This article presents the results of tests to determine the magnitide of this effect together with an approximate theoretical treatment.

Triaxial tests on remoulded London clay, employing rubber membranes of three different thicknesses, when compared with unconfined compression tests at the same moisture content show that the strength contributed by the rubber membrane is:— independent of specimen strength proportional to the stiffness of the membrane independent of cell pressure.

In compression tests, with the specimen enclosed in a rubber membrane but with no lateral pressure, the effect is smaller than in the normal triaxial test.

Filter paper drains, used to accelerate consolidation, add further to the compression strength and consequently a larger correction must be applied to the measured strength.

A method for estimating the rubber correction from a simple extension test on a typical membrane is suggested.

Dans l'essai de compression non-drainée triaxial, les membranes de caoutchouc renfermant les spécimens produisent une augmentation apparente de résistance. Cet article donne les résultats des essais faits pour déterminer la grandeur de cet effet, ainsi que le traitement théorique approximatif.

Des essais triaxiaux sur de l'argile de Londres remoulée, employant des membranes de caoutchouc de trois épaisseurs différentes, ont été comparés à des essais de compression libre à la même teneur en humidité, et montrent que la résistance contribuée par la membrane de caoutchouc est:— indépendante de la résistance du spécimen, proportionnelle à la raideur de la membrane, indépendante de la pression de la cellule.

Dans les essais de compression avec le spécimen renfermé dans une membrane de caoutchouc mais sans pression latérale, l'effet est moindre que dans l'essai normal triaxial.

L'épuisement par papier-filtre, employé pour accélérer la consolidation, ajoute encore à la résistance à la compression et, par conséquent, une correction plus importante de la résistance mesurée doit être faite.

Une méthode est proposée pour évaluer la correction par rapport au caoutchouc en partant d'un essai d'extension simple sur une membrane-type.
Foundations for Ringsend Power Station, Dublin
Authors: MacDonald Joseph
Published: October 2009

Synopsis

This article describes the “Benoto” system for sinking 3-foot-3-inch-diameter steel cylinders through water-bearing gravel and silt to bedrock at a depth of approximately 140 feet below ground surface level.

Sinking of a cylinder is effected under its own weight by grabbing-out the contained material while, at the same time, the cylinder is continually rotated backwards and forwards about its vertical axis through an angle of 8 degrees.

When a cylinder is sunk to sound rock, it is filled with concrete thus forming a pile which is to carry a load of approximately 450 tons, including its own weight, together with frictionally applied load from settlement of the surrounding ground.

The specialized plant used in sinking is a “Benoto” grab and a “Benoto” tubing machine. The grab is a 35-inch-diameter, single rope type, weighing 1,984 lb. and operated by a crane made for the purpose. The tubing machine consists of a double acting hydraulic jack operated by a hydraulic pump. The jack oscillates a 21-foot-6¼-inch-long lever arm which is clamped to the cylinder.

Cet article décrit le système “Benoto” pour enfoncer des cylindres en acier de 3 pieds 3 pouces de diamètre à travers du gravier aquifère et du limon jusqu'aux roches de fond à une profondeur d'environ 140 pieds au-dessous du niveau du sol.

L'enfoncement d'un cylindre s'effectue par son propre poids tandis qu'on en arrache les matériaux qu'il contient et qu'en même temps on le fait continuellement basculer d'arrière en avant sur son axe vertical selon un angle de 8 degrés.

Quand un cylindre est enfoncé jusqu'aux roches fermes, on le remplit de béon et il forme ainsi un pieu qui doit supporter une charge d'environ 450 tonnes, son propre poids inclus, ainsi que la charge qui s'applique par friction provenant de l'affaissement du sol environnant.

La machinerie spécialisée employée dans l'opération d'enfoncement est une benne-drague “Benoto” et une machine à tuyautage “Benoto.” La drague, qui est du type à un seul cable, a 35 pouces de diamètre, pèse 1,984 livres (anglaises). Une grue spéciale la fait fonctionner. La machine à tuyautage se compose d'un vérin hydraulique à double effet actionné par une pompe hydraulique. Le véin fait osciller un levier de 21 pieds 6 pouces qui est agrafé au cylindre.
A General Plasticity Theory for Clay
Authors: Hansen J. Brinch
Published: October 2009

Synopsis

For fully saturated clay with internal friction and cohesion the equations of a general plasticity theory have been developed, assuming a linear increase of the undrained shear strength with the depth, as well as a sinusoidal variation of this strength with the inclination of the failure plane.

In this general case the “ Rankine ” solution has been investigated and applied to the earthpressure problem. The result confirms the correctness of the usual procedure, which consists of adding or subtracting twice the shear strength, provided that this shear strength is taken as half the compression strength at the depth in question and for shear along the failure plane in question. The inclination of the failure planes is, however, 45° ± ½ φe instead of 45°.

In the special case of homogeneous, isotropical clay (with internal friction) a “ Prandtl ” type solution has been investigated and applied to the foundation pressure problem. Also in this case the result confirms the correctness of the usual formula with a factor (2 + π) on the shear strength, provided that this shear strength is taken as half the compression strength. The rupture-figure is, however, completely different from the ordinary Prandtl figure.

Pour de l'argile arrivée à complète saturation avec frottement interne et cohésion, des équations d'une théorie générale de plasticité ont été. développées, en supposant une augmentation linéaire de la résistance non drainée de cisaillement avec la profondeur, ainsi qu'une variation sinusoidale de cette résistance avec l'inclinaison du plan de fléchissement.

Dans ce cas général des recherches ont été faites sur la solution “ Rankine ” et son application au problème de pression du sol. Le résultat confirme l'exactitude du procédé d'usage, qui consiste à additionner ou à soustraire deux fois l'effort de cisaillement pourvu que cet effort de cisaillement soit pris commé la moitie de la résistance de compression a la profondeur en question et pour le cisaillement le long du plan de flechissement en question. L'inclinaison des plans de flèchissement est pourtant de 45° ± ½ φe au lieu de 45°.

Dans le cas spécial d'argile homogène, isotropique (avec frottement interne) l'on a fait des recherches sur un type de solution “ Prandtl” que l'on a appliquée au problème de la pression de base. Dans ce cas aussi le résultat confirme l'exactitude de la formule habituelle avec un coefficient (2 + π) sur l'effort de cisaillement, pourvu que cet effort de cisaillement soit pris comme la moitié de la résistance de compression. Le coefficient de rupture est, cependant, complètement différent du coefficient ordinaire Prandtl.
The In-Situ Measurement of Young's modulus for rock By a dynamic method
Authors: Brown P. D. , Robertshaw Jack
Published: October 2009

Synopsis

This short article describes a simple method of determining Young';s Modulus of rock foundations in situ. The method relies upon the close correlation which is shown to exist between Young's Modulus and the longitudinal wave velocity in a rock, and involves only the measurement of the longitudinal wave velocity.

A method of measuring the longitudinal wave velocity in a rock is described, with particular reference to measurements recently made on a dam site in Iraq.

Ce bref article décrit une méthode simple pour la détermination du module d'élsticité des fondations de roche in situ. La méthode est basée sur l'étroite corrélation qu'on démontre exister entre le module d'élasticité et la vélocite longitudinale d'ondes dansune roche, et n'implique que la mesure de la vélocité des ondes longitudinales.

On décrit une méthode pour mesurer la vélocité longitudinale des ondes dans une roche, et notamment les mesures effectuées récemment sur un emplacement de barrage en Iraque.
Consolidation Des Sols (Étude Mathématique)
Authors: Mandel J.
Published: October 2009

Synopsis

Terzaghi a donné la solution du problème du tassement d'une couche d'argile dans un cas particulier: celui d'une couche soumise à une pression normale uniforme. Dans ce cas la filtration se fait suivant la direction perpendiculaire à la couche et le phénomène est indépendant des coordonnées dans le plan de la couche. L'auteur de cet article fait une étude générale du problème du tassement; il indique la forme générale de la solution, et précise entièrement celle-ci dans le cas d'une couche plane et d'une force concentrée à la surface du sol.

Terzaghi has given the solution of the problem of the settlement of a stratum of clay in a particular case—that of a stratum subjected to a normal uniform pressure. In this case, the percolation takes place in a direction perpendicular to the stratum and the phenomenon is independent of the co-ordinates of the plane of the stratum. The Author makes a general study of the problem of settlement, and indicates the general form of the solution. He then gives the full solution in the case of a plane stratum and of a force concentrated on the surface of the soil.
An Apparatus for Triaxial-Compression Tests at High Pressures
Authors: Golder H. Q. , Akroyd T. N. W.
Published: October 2009

Synopsis

An apparatus for carrying out triaxial-compression tests on hard soils and soft rocks up to lateral pressures of 1,000 lb per square inch is described. The preparation of samples of these materials is discussed, and some suitable methods of preparation are described. Test results are given, and it is pointed out that, for very strong materials, the range of pressure which is normally employed is insufficient.

Get article donne une description d'un dispositif permettant d'effectuer des essais triaxials sur des sols durs et des roches tendres, les pressions latérales s'élevant jusqu'à 70,3 kg-cm2. On y parle également de la préparation d'échantillons de ces matériaux ainsi que de certaines des méthodes appropriées de préparation.

L'article comprend en outre des résultats d'essais et l'on souligne notamment que, pour des matériaux très résistants, la gamme des pressions utilisées n'est pas suffisante.
Subsoil Exploration for a Bridge Over the Parana River, Argentina
Authors: Moretto Oreste
Published: October 2009

synopsis

A site exploration for a proposed bridge over the Paraná River, in Argentina, offered an opportunity to study the correlation between penetration resistance and the relative density of sand. The method of subsoil exploration used is described and the results obtained are given.

Une reconnaissance d'emplacement du chantier pour la construction envisagée d'un pont sur la Paraná, en Argentine, a fourni l'occasion d'étudier le rapport entre la résistance à la pénetration et la densité relative du sable. La methode de la reconnaissance du sous-sol utilisée fait l'objet d'une description et l'on donne également les résultats obtenus.
The Use of Pore-Pressure Coefficients in Practice
Authors: Bishop A. W.
Published: October 2009

Synopsis

The pore-pressure coefficients defined by Skempton (1954) have been applied to the problems of determining the effective stresses in an earth dam during construction and during rapid draw-down. Reference is made also to several other practical applications of these coefficients.

Les coefficients de pression interstitielle définies par Skempton (1954) ont été appliqués aux problèmes du calcul des tensions efficaces dans une barrage en terre, en tours de construction ainsi que durant un affaissement rapide. Il est fait mention également de diverses autres applications de ces coefficients.
The Seismic Determination of Young's Modulus and Poisson's Ratio for Rocks in Situ
Authors: Evison F. F.
Published: October 2009

Synopsis

The velocities of shear and compressional seismic waves in a rock may together be used to calculate the value of Poisson's ratio in situ, and if the density is known the value of Young's modulus may be calculated as well. Experiments have been carried out in which these two types of wave were generated first by means of an electrically driven vibrator in the volcanic rock ignimbrite, and secondly in the concrete of a dam. From the velocities measured in each case the following elastic constants were calculated: for ignimbrite, µ = 0·41, E = 460,000 lb/sq. in.; for concrete, µ = 0·21, E = 3,600,000 lb/sq. in. The value of E for ignimbrite was much smaller than would have been deduced from the compressional velocity alone, with the usual assumption as to the value of µ, and much larger than that given by the standard static compression test. The value for concrete was nearly the same by all three methods.

Les vélocités des ondes séismiques de cisaillement et de compression dans une roche peuvent être utilisées ensemble pour calculer la valeur du rapport de Poisson in situ, et si la densité est connue la valeur du module de Young peut également être calculée. Des expériences ont été effectuées dans lesquelles on produisit ces deux genres d'ondes à l'aide d'un vibrateur commandé électriquement, en premier dans les roches volcaniques ignimbrite, et en second lieu dans le béton d'un barrage. D'après les vélocités mesurées dans chaque cas les constantes élastiques suivantes furent calculées: pour l'ignimbrite, µ0,41, E 460.000 lb/pouce carré ou 32.200 kg:cm2; pour le béton µ0,21, E 3.600.000 lb/pouce carré: ou 252.000 kg:cm2. La valeur de E pour l'ignimbrite était beaucoup plus petite que celle qui aurait été déduite de la vélocité de compression seule, avec la supposition usuelle concernant la valeur de µ, et beaucoup plus grande que celle donée par l'essai normal de compression statique. La valeur pour le béton était à peu près la même par toutes les trois méthodes.
The Slide in Lodalen, October 6th, 1954
Authors: Sevaldson R. A.
Published: October 2009

Synopsis

The Paper describes a slide in a clay slope near a marshalling yard in Oslo in 1954. The slope was originally excavated about 30 years earlier during the expansion of the rail facilities. Since the slide took place apparently without any sudden external cause, it can be considered as the result of a gradual reduction in stability of the slope during the past years.

Comprehensive field investigations and laboratory studies were carried out in order to determine the properties of the clay.

Stability calculations by the φ = 0-analysis, based on values of the undrained shear strength which could be expected to exist in the slope immediately before the slide give a correct result, but involve a number of uncertain factors. It is, however, inappropriate to use this method for estimating the long-term stability.

Stability analyses by Bishop's method, in terms of effective stresses based on the apparent cohesion and the apparent angle of friction, give approximately correct results. This method is, in addition, appropriate for estimating the long-term stability of the slope.

L'article ci-après décrit un éboulement dans un versant d'argile près d'une gare de manutention dans la banlieue d'Oslo. L'éboulement, qui se produisit apparemment sans cause extétrieure déterminante, doit être considéré comme un phénomène à longue échéance, dû au fait que par suite du déblaiement en vue d'entendre les voies de manutention, le versant d'argile reçut une trop grande pente. I1 fut procédé à d'amples recherches du sol et essais de laboratoire pour déterminer les caractéristiques de l'argile en présence.

Les calculs de stabilité: par les analyses φ = 0, basés sur les valeurs de l'effort de cisaillement non asséché, que l'on pouvait supposer exister dans le talus immédiatement avant l'éboulement, donnent un résultat correct, mais entraînent un nombre de facteurs incertains. Il est toutefois peu approprié d'employer cette méthode pour estimer la stabilité à long terme.

Les analyses de stabilité par la méthode de Bishop en termes d'efforts effectifs basés sur la cohésion apparente et l'angle de frottement apparent donnent des résultats qui sont approximativement corrects. Cette méthode est de plus appropriée pour estimer la stabilitié à long terme du talus.
Volume Changes in Drained Taixial Tests on Granular Materials
Authors: Newland P. L. , Allely B. H.
Published: October 2009

Synopsis

Starting from the basis that the direction of sliding of one particle relative to another is, in general, inclined at an angle to the direction of the applied shear stress, a theory is developed to account for the difference between peak and residual stresses in terms of the volume expansion of the mass during shear. A reason is given to explain why the theory based on energy considerations cannot fully account for this difference.

It is also suggested that the observed differences between the angle of sliding friction øμ (= tan−1μ) and the angle of internal friction øf are explainable in terms of the mode of failure which is itself a function of øμ. The analysis is extended to cover both direct and triaxial shear tests.

Experimental results obtained from triaxial tests on samples of lead shot are presented and the pro-posed theory appears to fit these results, after several modifications have been made to them, better than the theory based on energy considerations.

Tests on a set of samples lubricated with graphite are a novel feature of the experimental programme, and the results from these tests coupled with the results obtained from sliding friction tests are shown to be in general agreement with the proposed theory.

Partant du fait que la direction de glissement d'une particule par rapport à une autre est, en général, inclinée a un angle en direction de l'effort de cisaillement appliqué, une théorie est developpée pour expliquer la difference entre l'effort maximum et l'effort constant en termes du volume d'expan-sion de la masse pendant le cisaillement. On donne une raison pour indiquer pourquoi la theorie basee sur des considerations d'energie ne peut pas expliquer complétement la différence.

I1 est également suggéré que les différences observees entre l'angle de friction de glissement øμ(= tan−1μ) et l'angle de friction interne øf sont explicables en termes du mode de rupture, qui lui- même est fonction de øμ L'analyse est étendue pour couvrir tant les essais directs que les essais & trois axes de cisaillement.

Les résultats expérimentaux obtenus par des essais a trois axes sur des echantillons de grenaille de plomb sont présentés et la théorie proposée prouve qu'elle s'accorde avec ces résultats, après y avoir apporte plusiers modifications, bien mieux que la theorie basée sur des considerations d'energie.

Des expériences sur un jeu d'échantillons lubrifiés au graphite sont une nouveauté du programme expérimental et les résultats de ces expériences, ajoutes à ceux obtenus des experiences de friction de glissement, sont, dans l'ensemble, d'accord avec la theorie proposée.
Foundation Design and Behaviour of Tower Latino Americana in Mexico City
Authors: Zeevaert Leonardo
Published: October 2009

Synopsis

The foundation design for the forty-three storey building Tower Latino Americana in Mexico City introduced new and interesting problems in foundation engineering. The Paper describes the general philosophy adopted in the design of the foundation of this building. A detailed description of subsoil conditions and mechanical properties of the lacustrine deposits encountered at the site is given.

The ground surface subsidence problem and investigations performed to discover the source of compression of the clay deposits are described, and the way this phenomenon was taken into account when consideration was given to the foundation design.

Excavations into the lacustrine volcanic clay deposits in Mexico City produce large heave. The Author describes the procedure used to excavate to a 13-m depth for the foundation structure, and to avoid the heave of the bottom of the excavation and the excessive settlement of adjacent buildings and streets.

Settlement observations are reported—of the building, of the ground surface, and other deepseated strata. Piezometric water-level observa- tions during construction, and afterwards, are also dealt with.

Finally, a comparison of observed and computed settlements is given in an attempt to predict the future behaviour of the foundation of the building.

Le plan de fondation du bâtiment de quarantetrois étages Tour Latino Americana à Mexico a posé de nouveaux et intéressants problèmes de travaux de fondations. L'article décrit la philosophie générale suivie pour le plan de fondation de ce bâtiment. On y donne une description détaillée de l'état du sous-sol et des propriétés mecaniques des dépôts lacustres rencontres sur le chantier.

Le problème d'affaissement de la surface du sol et les recherches faites pour decouvrir l'origine de compression des dépôts d'argile y sent décrits, ainsi que la manière dont ce phénomène fut traité lorsque fut considéré le plan de fondation.

Les excavations dans les dépôts lacustres d'argile volcanique à Mexico produisent de fort soulèvement.

L'auteur décrit la méthode employée pour creuser à 13-m de profondeur afin de mettre en place la structure de fondation, en évitant le soulèvement du fond de l'excavation et le tassement excessif des bâtiments et rues avoisinants.

Y sont rapportées des observations sur le tassement du bâtiment, de la surface du sol et d'autres couches profondes.

On traite aussi des observations piézométrique de niveau d'eau pendant la construction ainsi qu'après.

Enfin, les tassements observés sont comparés aux tassements estimés dans l'intention de prédire le comportement futur de ce bâtiment.
Thermal Treatment as a Means of Improving the Stability of Earth Masses
Authors: Beles A. A. , Stănculescu I. I.
Published: October 2009

Synopsis

The Paper outlines some characteristic aspects of the available methods for improving the stability of earth masses through thermal treatment. Laboratory tests results are discussed, and some of the published data on the technological processes used are described. Details are given on a new procedure of thermal treatment by burning gas oil in borings, using free draught air supply.

The Paper includes the description of some practical application of the new thermal treatment procedure as a method for improving the stability of clay soil masses.

L'article donne un aperçu sur quelques aspects caractéristiques de la méthode à assurer la stabilité des massifs de terre par le traitement thermique. On présente les résultats des essais de laboratoire et on décrit quelques-unes des données publiées sur les processus technologiques utilisés. On détaille un nouveau procédé de traitement thermique; on brule du gas oil dans Ies forages, utilisant un tirage libre d'air.

L'article contient la description de quelques applications pratiques du nouveau procedé de traitement thermique employé comme une méthode d'améliorer la stabilité des massifs d'argile.
The Progress of Consolidation in a Clay Layer Increasing in Thickness with Time
Authors: Gibson R. E.
Published: October 2009

Synopsis

The Paper deals with the one-dimensional consolidation of a clay layer which increases in thickness with time. The pore-water pressures are generated by the increasing weight of superincumbent material and the length of the drainage path varies. Because of these unusual features the standard methods of analysis are inapplicable except in the special instance when the thickness of the layer is proportional to t½.

It is shown that in general the problem can be reduced to a linear integral equation, a solution of which is obtained for the case of deposition at a constant rate. In conclusion an example is given of a numerical procedure for estimating the progress of consolidation in a rolled fill dam during construction.

Cet article traite de la consolidation en une dimension d'une couche argileuse dont l'épaisseur croit en fonction du temps. L'accroissement de la charge, dû au poids de matéria1 qui se superpose, engendre les pressions interstitielles, et concurremment la longueur du parcours de drainage varie. A cause de ces Caractéristiques spéciales, les méthodes ordinaires ne peuvent être appliquées sauf dans le cas particulier ou l'épaisseur de la couche est proportionelle a` t½.

II est démontré qu'un général le problème peut ètre réduit à une équation intégrale linéaire, et une solution est obtenue pour le cas d'une dépôt a taux constant. En conclusion, un exemple expose un procédé numérique pour évaluer la consolidation progressive durant la construction dans un remblai roulé d'un barrage.
The One-Point Method of Determining the value of the Liquid Limit of a Soil
Authors: Norman L. E. J.
Published: October 2009

Synopsis

The Paper describes an analysis made of the data obtained during the determination of the liquid limit of 455 British soils and 49 soils from overseas made with the object of examining the reliability of the one-point method of determining the liauid limits of soils.

It was found that the one-point method was as accurate as the standard method for the soils examined and that the accuracy obtained was usually of the same order as that determined by other workers in the United States of America and Canada. It was found that withsoils with liquid limits exceeding 120% the order of accuracy was not sufficiently good to justify the use of the one-point method with such soils.

For normal classification purposes the method is recommended as a convenient alternative to the standard method and a suggested procedure is given.

Cet article décrit une analyse des données recueillies lors de la determination de la limite de liquidité de 455 sols britanniques et 49 sols d'outre- mer, faite pour examiner la sûrete de la méthode à point unique determinant les limites de liquidité des sols.

On découvrit que la méthode à point unique est aussi precise que la methode courante pour les sols examines et que la precision obtenue était habituellement du même ordre que celle qui fut determinée par d'autres travailleurs aux Etats Unis d'Amérique et au Canada. On découvrit que pour les sols a limite de liquidité dépassant 120% l'ordre de grandeur de la précision n'est pas assez bon pour justifier l'emploi de la méthode a point unique avec de tels sols.

Pour des fins de classement normal on recommande cette mitthode en tant qu'alternative pratique à la méthode courante et on en donne une procédure recommandée.