bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of the exothermic hydration process of Portland cement
Authors: Swaddiwudhipong S. , Chen D. , Zhang M. H.
Published: October 2009

A numerical model is proposed to simulate the exothermic hydration process of cement and temperature rise in mass concrete pours. The hydration reaction of each major mineral compound found in Portland cement, C3S, C2S, C3A and C4AF, is considered. The hydration of each mineral compound is characterised by its two material functions, namely, the thermal activity and the reference rate of heat of hydration. The influences of various factors on the exothermic hydration process are taken into consideration. The applicability of the proposed model is verified by a series of adiabatic temperature rise tests. With the establishment of this approach, it is possible to simulate the exothermic hydration process of Portland cement and the temperature rise directly on the basis of intrinsic mechanism of hydration, chemical composition of cement and mix proportion of concrete mixture.
Effect of leaching conditions and curing time on the leaching of heavy metals in fly ash cement mortars
Authors: Nagataki S. , Yu Q. , Hisada M.
Published: October 2009

The main aspect in respect of environmental compatibility and impact of cement-based materials is the leaching of inorganic compounds when they are contact with environmental waters. The leaching of heavy metals Cr (total chromium and of Cr6+), Pb, Cd, Zn, Mn, Co, V, Ti, Ni and Cu in fly ash cement mortars has been investigated by tank leaching and shaken extraction test methods; comparisons are made between the leachability of heavy metals under different pH conditions and of metals from specimens at different curing ages. In addition, a pH controlled shaken extraction test method is proposed; an advantage of this method is that leachant pH remains nearly constant at 6.6 ± 0.3 throughout the extraction process, leading to the diminution of the impact of pH variation of leachant on the leachability of heavy metals. The results of this study mainly indicate that: (a) heavy metals do leach from the tested cement mortars, but the amount leached is small; with increasing fly ash addition and water to binder ratio the leaching of heavy metals from cement mortars increases; (b) in a tank leaching test, the leaching of heavy metals from fly ash cement mortars is also a diffusion controlled process; compared with the tank leaching test, a shaken extraction test can extract more toxic heavy metals from hardened mortars; (c) the leachability of some heavy metals is greatly dependent on leachant pH: for example at pH around 7, leaching of Mn, Zn, total Cr (Cr for short in the following), Cr6+ and Pb will be much increased in comparison to that at pH over 12; (d) the leaching of Co, total Cr and Cr6+ from cement mortars is reduced with curing age, but no evident effect of curing age on the leaching of Cd, Ti, Ni, Mn, Zn and V has been observed; and (e) increased leaching of both Cr and Cr6+ will occur when cement mortars have been carbonated.
History of high-alumina cement. Part 1: Problems and the Stone report
Authors: Neville A.
Published: October 2009

The paper is published in two parts. Part I presents a lead-up to the Stone Committee. A brief description of high-alumina cement (HAC) is given and the problems with its use in structures are outlined. The body of the Stone Committee report is then dealt with and some more widely applicable conclusions of the report are discussed. Part II (Engineering History and Heritage, 2009) discusses the background to HAC problems in the light of the Stone Committee report as well as the present-day situation.
Deformations of model reinforced-soil retaining walls due to creep and reinforcement pullout
Authors: Kazimierowicz-Frankowska K.
Published: October 2009

The paper describes experimental investigations of vertical reinforced soil walls. The structures were built at small scale, under laboratory conditions. Horizontal displacements on the surface of the walls were measured. The theoretical analysis of the experimental results is elaborated. The influence of two elements (reinforcement creep and reinforcement pullout) determining the magnitude and pattern of deformation are selected and described. Good agreement between the theory and experiments is obtained.
Performance of different geosynthetic reinforcement materials in sand foundations
Authors: Dash S. K. , Rajagopal K. , Krishnaswamy N. R.
Published: October 2009

This paper presents the results of laboratory model tests carried out to study the relative performance of different forms of reinforcement (i.e. geocell, planar and randomly distributed mesh elements) in sand beds under strip loading. The results demonstrate that geocell reinforcement is the most advantageous soil reinforcement technique of those investigated. With the provision of geocell reinforcement, failure was not observed even at a settlement equal to about 45% of the footing width and a load as high as eight times the ultimate capacity of the unreinforced soil, whereas, with planar reinforcement, failure took place at a settlement of about 15% of the footing width and a load of about four times the ultimate capacity of the unreinforced soil. For the case with randomly distributed reinforcement mesh, failure was recorded at a load of about 1.8 times the ultimate capacity of the unreinforced soil and at a settlement of about 10% of the footing width.
Internal and interface shear strengths of unreinforced and needle-punched geosynthetic clay liners
Authors: Chiu P. , Fox P. J.
Published: October 2009

This paper presents information from a large database that has been compiled on internal and interface shear strengths of geosynthetic clay liners (GCLs). The data were obtained from the literature, GCL manufacturers, and the authors' own tests, and are representative of the most common materials and interfaces used in the construction of landfills and other facilities that incorporate GCLs as hydraulic barriers. Internal shear strengths are presented for unreinforced and needle-punched GCLs. Interface shear strengths are presented for needle-punched GCLs placed against smooth geomembranes, textured geomembranes, drainage geocomposites, and soil. Peak and large-displacement shear strengths are reported, along with displacements at peak strength and post-peak strength ratios. The database is useful for: (1) gaining insight into the shear behavior of GCLs; (2) illustrating the variability of GCL shear test results; (3) obtaining preliminary strength parameters prior to conducting project-specific shear tests for final design; and (4) comparing with the results of future shear tests on similar or new GCL products.
Lower-bound shear strength for geosynthetic clay liners in base liners
Authors: Gilbert R. B. , Wright S. G. , Shields M. K. , Obermeyer J. E.
Published: October 2009

The objective of this paper is to establish the minimum available shear strength for any type of geosynthetic clay liner (GCL) in a base liner. Direct shear tests are conducted on very thin (nominally 1 mm thick) specimens of reconstituted bentonite placed against a smooth geomembrane to measure the drained, residual strength of this interface. The use of thin specimens minimizes the time required to achieve drained conditions, and also minimizes the shear displacement required to mobilize the residual strength; testing times were several weeks and residual strengths were mobilized within 10 mm of shear displacement. The Mohr–Coulomb strength envelope developed from these test results corresponds to a secant friction angle of 4.7° over a range of effective normal stresses from 250 to 1500 kPa. Limited published information for the shear strength of bentonite and GCLs at these effective normal stresses supports the use of this envelope as a lower-bound strength for all types of GCL. This envelope establishes a conservative design check for slope stability and a benchmark for evaluating product-specific and project-specific test results with GCLs.
Reliability-based stability analysis considering GCL shear strength variability
Authors: McCartney J. S. , Zornberg J. G. , Swan R. H. , Gilbert R. B.
Published: October 2009

The impact of different levels of uncertainty in geosynthetic clay liner (GCL) shear strength on landfill stability is evaluated in this study. The uncertainty in shear strength of the interface governing landfill stability is defined using statistical parameters obtained from a significant database of GCL internal and GCL–geomembrane interface large-scale direct shear tests. Uncertainty in GCL shear strength arises from material variability within a single product type and between different product types. For a given product type, uncertainty arises from material differences among specimens from the same manufacturing lot as well as among specimens from different manufacturing lots. In addition, uncertainty was observed to arise from differences in test procedures such as hydration, consolidation and shear displacement rate. A framework for incorporating the observed laboratory shear strength variability into realistic field applications is presented. Reliability-based stability analyses were used to assess the impact of uncertainty in laboratory GCL shear strength test results on conventional design methodologies. Specifically, the impact of uncertainty on the relationships between the conventional safety factor and the probability of failure is assessed. Owing to the high shear strength variability observed in the database, high probability of failure values were found to correspond to safety factors typically used in geotechnical practice.
Hydraulic conductivity of a dense prehydrated GCL permeated with aggressive inorganic solutions
Authors: Kolstad D. C. , Benson C. H. , Edil T. B. , Jo H. Y.
Published: October 2009

A series of swell and hydraulic conductivity tests were conducted with aggressive aqueous solutions (1 M CaCl2, 1 M NaCl, HCl solution with pH 1.2, and NaOH solution with pH 13.1) and deionised water (DI) on two GCLs. One GCL is moistened with an aqueous solution and calendered during manufacturing to form a dense prehydrated (DPH) GCL having a mass of dry bentonite per area (MA) of 6.0 kg/m2. The other is a conventional GCL containing air-dried granular bentonite with MA = 4.3 kg/m2. The montmorillonite fraction of the bentonite is similar in both GCLs (81% conventional, 89% DPH). Comparable free swell was obtained with both bentonites in the NaCl, CaCl2 and acidic (HCl) solutions. However, with the basic (NaOH) solution, free swell of bentonite from the DPH GCL was 90% larger than that from the conventional GCL. The hydraulic conductivity tests were conducted for approximately 300 days. The DPH GCL had much lower hydraulic conductivity to all permeant liquids than the conventional GCL. For example, the hydraulic conductivity of the DPH GCL to 1 M CaCl2 is 3.7 × 10−12 m/s, whereas it is 9.1 × 10−7 m/s for the conventional GCL. The hydraulic conductivity of the DPH GCL to DI water is also three times lower than that of the conventional GCL (4.1 × 10−12 compared with 1 × 10−11 m/s).
Forensic analysis of excessive leakage from lagoons lined with a composite GCL
Authors: Benson C. H. , Jo H. Y. , Abichou T.
Published: October 2009

A forensic investigation of excessive leakage from two lagoons is described. The lagoons were lined with a composite geosynthetic clay liner (GCL) consisting of a thin geomembrane laminated to one side of a conventional GCL (i.e. granular bentonite encased between two geotextiles). The GCL was installed with the geomembrane in contact with the subgrade. Layers of sand (150 mm) and gravel (300 mm) were placed on top of the GCL to protect it from wave action. Field-scale leakage rates were estimated by monitoring water levels with a graduated rod and by measuring the pressure at the bottom of each lagoon using pressure transducers. In addition, leakage through the GCL panels was measured in situ with sealed double-ring infiltrometers and in the laboratory using flexible-wall permeameters. Leakage rates for the overlaps were measured in the laboratory with flow box tests on GCL specimens from the lagoons. Tests were also conducted to assess the swelling capacity and ionic composition of the exchange complex of the bentonite component of the GCL, the ionic composition of the lagoon water, and the carbonate content of the soils adjacent to the GCL. Inspection of the GCL revealed minimal damage and showed that the installation was in general accordance with the manufacturer's recommendations. However, one of the lagoons had no supplemental bentonite in the panel overlaps, and the other lagoon had supplemental bentonite in less than one-half of the overlaps. Comparison of leakage rates estimated with the pressure transducers and those computed using the field and laboratory test data indicates that leakage through the overlaps without supplemental bentonite was the most likely cause of the excessive leakage. Leakage rates from overlaps without bentonite were as much as eight times higher than leakage rates from overlaps containing bentonite. Extensive ion exchange also occurred in the bentonite, but this factor appears not to have affected the leakage rate because of the hydraulic impedance provided by the geomembrane. Water contained in the lagoons is believed to be the primary source of the divalent and polyvalent ions involved in cation exchange.
A predictive model for seismic displacement of reinforced slopes
Authors: Paulsen S. B. , Kramer S. L.
Published: October 2009

Geosynthetic-reinforced soil structures have increased greatly in popularity over the past 20 years. Their adoption for use as permanent structures in seismically active areas, however, has been hindered by uncertainty regarding appropriate seismic design procedures. The development of such procedures requires analytical models capable of predicting the pertinent seismic response of geosynthetic-reinforced structures as a function of all of the significant variables that can be controlled by the designer. Operating under the assumption that permanent deformation is the best indicator of post-earthquake serviceability, this paper describes the development and validation of a practical model for estimation of the permanent displacement of reinforced slopes subjected to earthquake loading. The ability of the model to reasonably predict yield acceleration and time histories of permanent displacement in model tests is demonstrated, and its potential use as a design tool is discussed. A companion paper illustrates the practical use of the model.
Seismic performance evaluation of reinforced slopes
Authors: Kramer S. L. , Paulsen S. B.
Published: October 2009

The field of earthquake engineering is moving towards performance-based concepts for design and evaluation of buildings and bridges, and also geotechnical structures. Rather than basing a design or evaluation on a single ‘design’ seismic event or hazard level, performance-based earthquake engineering considers all possible hazard levels, including those less likely and more likely to occur than the design level. This paper illustrates the way in which the basic concepts of performance-based earthquake engineering can be applied to an evaluation of a reinforced slope. In doing so, it illustrates the practical use of a model for prediction of the permanent displacement of reinforced slopes that is described in a companion paper.
Determining the design parameters for geosynthetic reinforcements subject to multi-stage actions using the isochronous strain energy approach
Authors: McGown A. , Khan A. J. , Kupec J.
Published: October 2009

Geosynthetic-reinforced soil structures may be required to resist multi-stage actions, such as sustained plus traffic loading or sustained plus seismic loading. Current design codes/methods do not recognise possible differences that may exist between the response of geosynthetics to multi-stage actions and to single-stage actions. In this paper, it is suggested that the isochronous strain energy approach can be used to better interpret the load–strain–time behaviour of geosynthetics subject to multi-stage actions. Test data from sustained plus cyclic loading and sustained plus short-term loading are presented and analysed using the isochronous strain energy approach. Based on these analyses, two design methods are developed to take account of the various responses of geosynthetics to different forms of multi-stage loading.
Analysis of beams on reinforced granular beds
Authors: Maheshwari P. , Basudhar P. K. , Chandra S.
Published: October 2009

This paper presents a model for estimating the flexural response of beams resting on reinforced beds with reinforcing elements, such as geogrids, which are idealised as beams with smooth surface characteristics. The lower poor strata and the upper dense soil are modelled using Winkler springs of different stiffnesses. Taking a surcharge load on the reinforcing elements has incorporated the effect of depth of placement of the reinforced layer. The governing differential equations to find the response of the model have been derived, and closed-form analytical solutions are found subjected to appropriate boundary and continuity conditions. A particular case of the present study matches identically when compared with the solution obtained by Hetenyi for an infinite beam on an elastic foundation. For the range of parameters considered, the results show that practically no change occurs in the normalised deflection of upper and lower beams when the normalised length ratio of beams exceeds 1.5. Further, it is shown that the various parameters—the ratio of flexural rigidity of upper and lower beam, the ratio of stiffness of the upper and lower soil layers, and the ratio of the length of upper and lower beams and placement depth of the lower reinforcement—significantly affect the combined response of the model.
Peak versus residual interface strengths for landfill liner and cover design
Authors: Stark T. D. , Choi H.
Published: October 2009

The rationale for using peak, residual, or a combination of these shear strengths for the analysis of geosynthetic-lined slopes and design recommendations for landfill liner and cover systems is presented herein. Landfill liner systems using geosynthetics that contain sideslopes are recommended to be designed using the methodology presented by Stark and Poeppel: (1) assign residual shear strengths to the sideslopes and peak shear strengths to the base of the liner system and satisfy a factor of safety greater than 1.5; and also (2) assign residual strengths to the sideslopes and base of the liner system and satisfy a factor of safety greater than unity. The authors recommend that the stability of landfill cover systems be analysed using peak shear strengths with a factor of safety greater than 1.5 because of the absence of large detrimental shear displacement along the weakest interface. If, for some reason, the slope angle of the cover system exceeds the friction angle of the weakest interface, or large displacements such as construction-induced displacements or seismically induced displacements are expected, a residual shear strength with a factor of safety greater than unity should be used for the cover design. In both liner and cover designs a peak composite failure envelope that describes the weakest interface should be used to represent the peak shear strength, and the residual failure that corresponds to the peak composite failure envelope should be used instead of the lowest residual failure envelope.
Analysis and design of veneer cover soils
Authors: Koerner R. M. , Soong T.-Y.
Published: October 2009

Cover soil sliding on slopes underlain by geosynthetics is obviously an unacceptable situation and, if the number of occurrences becomes excessive, can eventually reflect poorly on the entire technology. Steeply sloped leachate collection layers and final covers of landfills are situations where incidents of such sliding have occurred. Paradoxically, the analytic formulation of the situation is quite straightforward. This paper presents an analysis of the common problem of a veneer of cover soil (0.3 to 1.0 m thick) on a geosynthetic material at a given slope angle and length. The paper then presents different scenarios that create lower FS (factor of safety) -values than the gravitational stresses of the above situation, e.g. equipment loads, seepage forces and seismic loads. As a counterpoint, different scenarios that create higher FS-values also are presented, e.g. toe berms, tapered thicknesses and veneer reinforcement. In this latter category, a subdivision is made into intentional reinforcement (using geogrids or high-strength geotextiles) and non-intentional reinforcement (cases where geosynthetics overlay a weak interface within a multilined slope). A standard numeric example is used in each of the above situations to illustrate the various influences on the resulting FS-value. In many cases, design curves are also formulated. Suggested minimum FS-values are presented for final closures of landfills, waste piles, leach pads, etc., which are the situations where veneer slides of this type are the most serious. Hopefully, the paper will serve as a vehicle to bring a greater awareness to this situation so as to avert such slides from occurring in the future. Note: This paper was initially published as the Giroud Lecture in the Proceedings of the Sixth International Geosynthetics Conference held in Atlanta, USA, in 1998.
Strain-hardening behaviour of fibre-reinforced sand in view of filament geometry
Authors: Consoli N. C. , Festugato L. , Heineck K. S.
Published: October 2009

The results from a series of laboratory drained standard triaxial tests conducted on sand specimens reinforced with randomly oriented discrete fibres are presented. The purpose of the testing programme was to quantify the stress–strain–strength behaviour of polypropylene fibre reinforced sand specimens considering different fibre lengths (up to 50 mm) and diameters (from 0.023 mm to 0.1 mm fibre), resulting in a large spectrum of aspect ratios (up to approximately 2200). Fibre reinforced specimens exhibited either strain-softening or strain-hardening characteristics, depending on the specific ranges of aspect ratio. Generally, longer fibres (high aspect ratios) produce higher strengths and strain-hardening behaviour in sand, allowing the mixture to be used as a geomaterial for embankments over soft soil, in which the material must withstand large deformations without losing its strength. However, very thin fibres (such as 0.023 mm diameter), longer than 24 mm, tangle during mixture, significantly reducing the effects of the fibres on the soil behaviour.
A new optical fibre sensor to assess the stability of geogrid-reinforced soil walls
Authors: Yashima A. , Tsuji S. , Yoshida K. , Yokota Y.
Published: October 2009

ABSTRACT: It is not easy to assess the stability of vertical soil walls reinforced by geogrids during and after construction. This paper describes a unique monitoring system called an ‘optical fibre sensor geogrid' in which an optical fibre sensor is installed within a longitudinal member of a geogrid reinforcement material. The structure of the optical fibre sensor and the measuring method to record strain in the geogrid are described. Laboratory tests were first carried out to assess the accuracy of geogrid strain measurements using the optical fibre sensor method. Optical fibre sensor geogrids were then used to measure the strain in embedded geogrid layers in three reinforced soil walls constructed in the field. The system allows the stability of reinforced soil walls to be monitored continuously during and after construction, and a stability evaluation index to be assigned to the walls based on peak strain readings.
Seismic behaviour of rigid-faced reinforced soil retaining wall models: reinforcement effect
Authors: Murali Krishna A. , Madhavi Latha G.
Published: October 2009

ABSTRACT: This paper presents the results of shaking table tests on models of rigid-faced reinforced soil retaining walls in which reinforcement materials of different tensile strength were used. The construction of the model retaining walls in a laminar box mounted on a shaking table, the instrumentation and the results from the shaking table tests are described in detail and the effects of the reinforcement parameters on the acceleration response at different elevations of the retaining wall, horizontal soil pressures and face deformations are presented. It was observed from these tests that the horizontal face displacement response of the rigid-faced retaining walls was significantly affected by the inclusion of reinforcement and even low-strength polymer reinforcement was found to be efficient in significantly reducing the deformation of the face. The acceleration amplifications were, however, observed to be less influenced by the reinforcement parameters. The results obtained from this study are helpful in understanding the relative performance of reinforced soil retaining walls under the different test conditions used in the experiments.
A general expression for geosynthetic strain due to deflection
Authors: Shukla S.K. , Sivakugan N.
Published: October 2009

ABSTRACT: Giroud [Geosynthetics International, 2, No. 3, 635–641, 1995] presented expressions for the strain within a geosynthetic layer assuming it to take the shape of a circular or parabolic arc. A more realistic situation would be one in which the deflected shape consists of both circular and parabolic arcs. This technical note presents an expression for the geosynthetic strain for a combination of parabolic and circular shapes of the deflected geosynthetic, which is commonly observed in many field applications of geosynthetics. The special simplified cases of this general equation, expected in field situations, are discussed in detail. The variation of geosynthetic strain with relative deflection, defined as a ratio of rut depth (maximum deflection, r) to the initial length (L0) of the geosynthetic, is presented to show the application limits of special simplified cases of the general equation. It is observed that the geosynthetic strain significantly depends on the shape of the deflected geosynthetic, especially at large rut depths. It is therefore recommended that the deflected geosynthetic shape considered must be exactly the same as the one observed or expected in the field application under consideration, especially at large strain levels. It is also shown that the approximate expression presented by Giroud holds for all possible shapes considered in this note, for small strains.
Electro-Osmosis in Soils
Authors: Casagrande Ing. L.
Published: October 2009

Summary

The present paper shows that, from a practical point of view, the electro-osmotic transport of water may be assumed to be constant for all soils. The magnitude of the osmotic permeability was found to be ke=5 × 10−5 cm. per sec. for for 1 volt per cm. By comparing ke, with the hydraulic permeability the heights to which the water can be shifted by electro-osmosis were computed and also measured by laboratory tests. For this purpose a special apparatus was constructed. The fact that with colloidal materials agreement between theoretical equilibrium heads and test results exist only for the short interval of time immediately after applying an electric potential was attributed to the development of cracks within the mass of material.

The possibility of diverting the flow of pore-water away from cuttings is discussed and illustrated by practical examples. Some indications are given of the magnitude of the required consumption of energy for a few arrangements of electrodes.

An explanation is also offered for the favourable effect of electro-osmosis on the consolidation of soft soil deposits.
Seepage into a Sheeted Excavation
Authors: McNamee John
Published: October 2009

Summary

A number of problems of steady two-dimensional seepage flow around sheeted excavations in porous media have been investigated at the Building Research Station in recent years. This paper presents a general survey of the work carried out and summarizes the more important results which have been achieved. The assumptions of the theory of seepage flow are reviewed briefly and the difficulty of interpreting the practical value of theoretical results is discussed. Some relaxation solutions for one type of problem are given and graphs have been prepared in order to facilitate the application of equilibrium criteria.

The application of the theory in the safe design of sheeted excavations is considered and some practical suggestions are offered.
Stresses in Rock About Cavities
Authors: Karl Teraghi , Richart F. E.
Published: October 2009

Synopsis

The article contains a discussion of the influenceof the shape of cavities, such as tunnels or spheroidal chambers, on the state of stress in the surrounding rock. The mathematical methods which have been used for computing the stresses are given in an appendix.

The results of the computations show that the stresses in the rock surrounding spheroidal cavities are lower than those in the rock about tunnels with the same cross-section, located at the same depth. As the ratio between the height and the diameter of a spheroidal cavity decreases, the stresses in the rock adjacent to the equator increase, but the height and width of the zone of stress concentration decreases. If the rock located within this zone is not strong enough to sustain the stresses, it flows or it is crushed, but the local failure has little influence on the state of stress in the rock above the roof of the cavity.

The most important error involved in the determination of the stresses is due to the uncertainties involved in the evaluation of the stresses which prevailed in the rock prior to the excavation of a cavity.

L'article examine l'influence de la forme de cavitiés, telles que tunnels ou caves sphéroīdales, sur le régime des tensions existant dans le roc environment. Une description des méthodes de calcul employeés pour calculer les tensions est donnee en Annexe.

Les résultats montrent que les tensions existant dans le rot autour d'une cavité sphéroīdale sont mains élevées que celles qui existent autour d'un tunnel de même section transversale et situé á la même profondeur. A mesure que le rapport entre la hauteur et le diametre diminue, les tensions existant dans le roc contigu a l'équateur augmentent mais la largeur et la hauteur de la zone de concentration des tensions diminuent. Si le rot est incapable de résister a ces tensions il se produit un écoulement ou un écrasement mais cette détérioration localisée n'influence guére le regime des tensions dans le rot au dessus de la cavité.

La source principale d'erreurs dans la détermination des tensions est l’incertitude concernant l'évaluation des tensions prédominantes dans le roc avant l'excavation.
Landslips in Norwegian Quick-Clays
Authors: Holmsen Per
Published: October 2009

Synopsis

In Norway, quick-clay deposits occasionally cause large landslips, or rather, landslides. This article attempts to give an outline of the mode of occurrence, the geographical distribution, some common features as to the mechanism, and supposed causes of the slips. Particular reference is given to the famous landslide in Værdalen, north of Trondheim, in 1893, where nearly 3 square kilo-metres of cultivated land, and about 55 million metres cubic metres were transformed into a heavy liquid, washing down the valley towards the fjord. One hundred and eleven persons lost their lives in this catastrophe.

En Norvège, des dépôts d'argiles mouvantes causent de temps en temps des affaisements importants ou, plutôt, des éboulements. Cet article essaie de donner un aperçu de la maniée dont ils se produisent, la répartition géographique, quelques traits communs quant au mécanisme, et des causes supposées de ces éboulements. L'on peut spécialement titer les fameux éboulemcnts de Værdalen, au Nord de Trondheim, en 1893, oú presque 3 kilo-métres carrés de terres cultivees et environ 55 millions de métres cubes furent transformés en un lourd liquide noyant la vallée vers le fiord. Cent onze personnes perdirent leurs vies dans cette catastrophe.
Considerations on the Sensitivity of Norwegian Quick-Clays
Authors: Rosenqvist I. TH.
Published: October 2009

Synopsis

The article gives an account, for the first time in English, of the work on sensitivity of the Norwegian quick-clays, published in 1946. These quick-clays are characterised by extreme sensitivities. They are of marine origin, but are found to differ from normal clays in having a low content of dissolved electrolytes, the greater part of the original salt having been removed by diffusion into moving ground-water, subsequent to deposition. The quick-clays do not differ appreciably in their mineralogy or grain size from normal clays of the same origin, and are sometimes found as lenticular bodies in normal clays. Their thixotropy is usually unimportant. A theory is outlined for the formation of the quick-clays.

L'article donne un compte-rendu, pour la première fois en Anglais, des travaux sur la sensibilité des argiles mouvantes norvègiens, publiés en 1946. Ces argiles mouvantes se caractèrisent par leur extrême sensibilité. Elles sont d'origine maritime, mais l'on a trouvé qu'elles différaient des argiles normales par un contenu peu élevé d'electrolytes dissoutes, la plus grande partie du se1 originel ayant été enlevee par la diffusion dans les nappes d'eau souterraines mouvantes par suite de dépôts.

Les argiles mouvantes ne différent pas de manière appréciable par leur minéralogie ou la taille de leur grain d'argiles normales de même origine, et on les trouve quelquefois, en tant que corps lenticulaires, dans les argiles normales. Leur thixotropy est habituellement peu important. Une théorie sur la formation des argiles mouvantes est esquissée.
The Bearing-Capacity Failure Of The Transcona Elevator
Authors: Peck R. B. , Bryant F. G.
Published: October 2009

Synopsis

In 1913, a grain elevator near Winnipeg, Canada, experienced a bearing-capacity failure during its first loading. The foundation consisted of a large rectangular raft resting on a plastic clay deposit. The load at failure is known. This article presents the results of tests made to determine the properties of the clay, and demonstrates that the failure occured at a pressure corresponding to the computed ultimate bearing-capacity of the clay.

The article is accommpanied by a supplementary not by Mr L. Scott White— an eye-witness of the incident.

En 1913 la rupture d'un silo près de Winnipeg, Canada, a eu lieu dont la cause était l'insuffisance de la force portante. Le silo était fondé sur unradier supporté par une couche d'argile plastique La charge au moment dela rup est connue.

Les qualités de L'argile sont indiquées par les resultats presentés ci-dessous des essais de sol sur des énchantillons intacts.

Ces résultats indiquent que la rupture a eu lieu sous une charge égale à la force portante limite calculée de l´argile.

L'article est accompagné d'une note supplémentaire par M. L. Scott White, qui était témoin à l'incident.
Some Investigations on Granular Soils With Particular Reference to the Compressed-Air Sand Sampler
Authors: Nixon I. K.
Published: October 2009

Synopsis

A new tool, much simpler than any previous type, for taking undisturbed samples of sand from below the water-table was introduced in 1948. Some investigations are described where its use has been important: (1) The crushing of a concrete sewer buried in sand. (2) Compaction from pile driving in a medium sand, resulting in a change of density from about 85 lb. per cubic foot to 101 lb. per cubic foot. (3) Measurement of the natural density of the Bracklesham sands. (4) The examination of laminated soils for ground-water lowering schemes. Continnous undisturbed samples have become an essential requirement when estimating the permeabili of laminated soils.

The use of the sand sampler on about 15 investigations has proved it to be very satisfactory, and no modifications have been necessary. All types of sand except coarse sand have been sampled. Occasionally, the examination of samples has revealed distinctive grain structures indicative of the lack of disturbance from the sampling. The relationship between the measured and in-situ density appears satisfactory for medium and loose deposits, but there is an indication that the measured densities are lower than the in-situ for dense deposits. Numerous samples have been taken from depths down to 100 feet, and one from a depth of 130 feet.

Une nouvelle machine-outil, et beaucoup moins compliquee que tout autre type anterieur, pour le prelevement des echantillons de sable intacts de dessous la nappe phreatique, fut introduite en 1948. Les resultats de quelques easais pour la realisation desquels l'emploi de cette outil a constitue une application importante, sont presentes: (1) l'crasement d'un dgout en beton enfonce dans la sable; (2) consolidation par suite de pilotage dans une sable moyenne, amenant a une variation de densite d'environ 85 livres par pied carre a 101 livres par pied ccarre; (3) la mesure de la densite propre des sables. de Bracklesham; (4) l'examen des sols laminaires pour des projets d'abaissement de la nappe phreatique. II faut des echantillons continns et intacts pour la determination de la permeabilite des sols laminaires. L'efficacite de l'chantilleur a sable s'est revelee comme satisfaisante pendant environ 15 essais, et aucunes modifications ne semblent necessaires. On a preleve des echantillons de toutes sortes de sable, sauf de la sable grossiere. De temps a autre, l'examen des echantillons a revele des structures de grain distinctives–ce qui indique qu'ils restent inacts apres l'chantillage. Le rapport entre la densite measuree et la densites sur place somble etre satisfaisant pour les couches measurees moyennes et molles, mais il apparait que les densites measurees sont plus faibles que les densites sur place pour des wuches epaisses. On a preleve dans une profondeur jusqu'a 100 pieds un grand nombre d'chautillons, dont un a une profondeur de 13 pieds.
Influence of Roughness of Base and Ground-Water Conditions On The Ultimate Bearing Capacity of Foundations
Authors: Meyerhof G. G.
Published: October 2009

Synopsis

Theoretical methods for estimating the effect of roughness of the base on the bearing capacity are outlined in the first part of the Paper and compared with the results of some loading tests on model footings.

In the second part of the Paper theoretical analyses of the influence of ground-water conditions on the bearing capacity of cohesionless material are summarised and compared with the main results of laboratory and some field loading tests on sand.

Dans la première partie du Document I'auteur expose dans leurs grandes lignes les méthodes théoriques propres à l'éevaluation de l'effet de la rugosité de la base sur la capacité portant et les compare avec les résultats de certains essais de charge sur des modèles de semelles.

Dam la seconde partie du Document, des analyses théoriques de l'influence des conditions avec nappes d'eau souterraines snr la capacité portante des matéeriaux non cohérents sont résumées et comparées avecles principaux résultats d'essais en laboratoire et de certains essais sur place de charge snr sable.
Evalution of Conefficients of Subgrade Reaction
Authors: Terzaghi Karl
Published: October 2009

Synopsis

The theories of vertical and horizontal subgrade reaction are based on the simplifying assumptions that the subgrade obeys Hooke's law, and that the subgrade reaction on the base of a rigid centrally loaded plate resting on the horizontal surface of the subgrade has the same value at every point of the base. Although these assumptions are not rigorously correct, the theories of subgrade reaction can be used for obtaining approximate solutions of many practical problems, such as the computation of the stresses in continuous footings acted upon by concentrated loads, or in piles that are intended to transfer horizontal load on to the subgrade. However, in order to get reasonably accurate results, the coefficients of subgrade reaction must be assigned values compatible with the deformation characteristics of the subgrade and the dimensions of the loaded area.

The Paper contains a discussion of the factors which determine the value of the coefficients of both vertical and horizontal subgrade reaction of cohesionless sand and stiff clay, and numerical values are proposed for the constants which appear in the equations defining these coefficients. It contains also brief reviews of the practical application of the theories of subgrade reaction.

Les théories de réaction verticale et horizontale des soubassement de terrassement sont fondées sur des hypothéses de simplification selon lesquelles la plateforme obéit à la loi de Hooke et que la réaction de soubassement sur la base d';une plaque rigide chargée centralement et reposant sur la surface horizontale de la soubassemcnt a la même valeur en tout point de cette base. Bien que ces hypothéses ne soient pas strictement correctes, les théories sur la réaction de soubassement peuvent être utilisées pour obtenir des solutions approximatives de nombreux problémes pratiques tels que le calcul des efforts dans des empattements continus sur lesquels agissent des charges concentrées ou dans des pieux qui ont pour but de transfércr la charge horizontale sur la soubassement. Toutefois, afin d'obtenir des semelles de fondation raisonnablement pécis, les coefficients de réaction de soubassement doivent recevoir des valeurs compatibles avec les caractéristiques de déeformation de la soubassement et avec les dimensions de la surface chargée.

Ce document comprend un examen des facteurs déterminant la valeur des coefficients à la fois de réaction verticale et de réaction horizontale de soubassement pour du sable non-cohérent et de I'argile raide. Y figurent en outre des valeurs suggérées pour les constantes apparaissant dans les équations qui définissent ces coefficients. Le Document donne aussi de brefs exposés sur l'application pratique des théories de réaction de soubassement.
Phenomena Connected with the Settlement Driven Piles
Authors: Bullen F. R.
Published: October 2009

Synopsis

Examination of many loading records has thrown light upon the frictional and toe values of the bearing capacity of a pile. The static toe values have been related to the elastic characteristics of the ground, and a connection found between these characteristics and the quake of the ground at the toe of the pile during driving.

L'examen de nombreux rapports de charge a élucidé les valeurs de frottement et du pied de la capacité portante d'un pieu. On a établi les rapports entre les valeurs statiques du pied et les caractéristiques élastiques du sol, et on a trouvé. une relation entre ces caractéristiques et le tremblement du sol au pied du pieu pendant l'enfoncement.
A Contribution to the Analysis of Stress in a Circular Tunnel
Authors: Morgan H. D.
Published: October 2009

Synopsis

In recent years progress has been made in the evolution of methods of tunnel lining which represent a marked departure from the traditional cast-iron lining. In designing such tunnel linings, it is necessary to relate the effects of stiffness of the lining to the characteristics of the ground since the strength of the lining is related to both factors.

In making a theoretical study of this problem it is necessary first to consider the effects on the state of stress in the ground around the tunnel due to its construction and the manner in which subsequent deformation of the tunnel lining may occur. Equations are then presented relating the stress set up in a tunnel lining directly to the stiffness of the lining and the elastic properties of the surrounding ground. Since the newer forms of tunnel lining are, on the whole, less stiff than the traditional lining, it is also necessary to consider the question of the stability of the lining. Known methods of analysis for critical external pressure on a thin tube have been developed to relate to a thin tube in an elastic medium.

Where a tunnel is driven in clay, long-term effects of consolidation settlement have also to be considered and relationships are established between the ultimate stress in a tunnel and the consolidation characteristics of the ground.

Field tests are being carried out which are expected to provide information on the application and limitations of the theoretical treatment.

Au cours de ces derniéres années l'évolution des méthodes de revêtement des tunnels a fait des progrès qui représentent une déviation nette de revêtements traditionnels en fonte. Dans la conception des tels revêtements de tunnels, il faut établir un rapport des effets de rigidité du revêtement aux caractéristiques du sol car la solidité du revétement est en rapport avec ces deux facteurs.

Pour faire une étude théorique de ce problême, il faut considérer d'abord les effets sur la condition de tension dans le sol autour du tunnel à cause de sa construction et de la maniére dont peuvent se produire les déformations consécutives du revêtement du tunnel.

Comme dans l'ensemble les nouvelles sortes de revêtements de tunnel sont moins rigides que les revêtements traditionnels, il faut considérer aussi la question de la stabilité du revêtement. Desméthodes d'analyse connues pour la pression extérieure critique sur un tube mince ont été développée pour établir un rapport avec un tube mince dans un milieu élastique.

Où on perce un tunnel dans l'argile, les effets à long terme de tassement d` à la consolidation doivent aussi être considérés et on établit des relations entre la tension limite de rupture dans un tunnel et des caractéristiques de consolidation du sol.

On est en train de faire des essais de chantier dont on attend des renseignements sur l'application et les limitations du traitement théorique.
Frictional Resistance of Bored Piles in Expansive Clays
Authors: Mohan Dinesh , Chandra Subhash
Published: October 2009

Synopsis

A series of loading and pull-out tests were carried out on cast-in-situ bored concrete piles in highly expansive clays (black cotton soils) at four different sites in India. It was found that the frictional resistance has the same value in pushing and pulling and is about half the average shear strength of the soil along the pile shaft.

Laboratory and field investigations show that the reduction in frictional resistance is due partly to the softening of the clay adjacent to the pile shaft and partly to the loss of adhesion between the concrete and the soil.

Une série d'essais de charge et d'arrachement a été faite sur des piles de béton en forage coulées sur place dans des argiles fortement expansibles (sols de “Cotton Noir”) à quatre endroits différent aux Indes. On a trouvé que la résistance à la friction a la même valeur en poussée et en traction et est d'environ moitié de la résistance moyenne au cisaillement du sol adjacent au puits de forage.

Les recherches de laboratoire et sur le terrain montrent que la diminution de la résistance à la friction est dûe en partie au ramollissement de l'argile adjacente au puits de la pile et en partie à la perte de l'adhesion entre le béton et le sol.