bluuebunny/crossref_metadata_2025 huggingface dataset:
Bending tests of large diameter fabricated steel cylinders
Authors: Kulak G. L. , Stephens M. J. , Bailey R. W.
Published: August 2008

Columns, stacks, conveyor galleries, and other similar civil engineering structures are often constructed in the form of an unstiffened tube or as a discretely stiffened tube that behaves in an essentially unstiffened manner. Tubes of this type are used extensively in the materials-handling operations of industrial plants. These are fabricated circular steel cylinders, typically 2.4-4 m in diameter, with radius-to-thickness ratios in the range of 150–400. They support and enclose conveyor systems, and they customarily span distances up to about 50 m. The task of the designer is similar to that faced with plate girders: the bending capacity, shear capacity, and the combined effects of shear and bending all must be examined. The results of a test program established to examine the flexural strength of large diameter fabricated steel tubes is reported herein. Although the number of tests is not great, the program is distinguished by the fact that the tests were done using relatively large specimens made in a way similar to that which would be employed in full-size tubes. These tests are believed to represent the best information currently available, and the results should be useful to both designers and other researchers who are approaching the problem using analytical tools. Key words: buckling, conveyors, pipes, steel, structural engineering, tubes.
Fatigue strength of prestressed concrete girder bridges
Authors: Al-Zaid Rajeh Z. , Nowak Andrzej S.
Published: August 2008

A model for evaluating the fatigue life of a prestressed concrete girder bridge is presented. Experimental studies indicate that fatigue is a random phenomenon. Therefore, the approach is based on probabilistic methods. The fatigue life of the prestressed concrete girder is estimated from the fatigue properties of its components, namely, the cast-in-place slab, precast beam, prestressing steel, and, if partially prestressed, the tension reinforcement. The model utilizes the available S–N curves for structural materials and Miner's rule to evaluate the fatigue life under variable amplitude loading. A model for determining the distribution function of time to first cracking is also presented. To demonstrate the developed models, a typical prestressed concrete girder bridge is analyzed. On the basis of this investigation, it is concluded that fatigue in prestressed concrete girder bridges designed according to the American Association of State Highway and Transportation Officials specifications is not a limiting design criterion. Key words: bridges, fatigue, prestressed concrete, structural reliability.
An example of advanced electronic macro spreadsheet programming
Authors: Neis M. E. , Neis V. V. , Wigham J. M.
Published: August 2008

The range of use of electronic spreadsheets to the solution of engineering problems is increasing with the advancements in spreadsheet software and computer hardware. The recent introduction of macro spreadsheets has added problem-solving capabilities of considerable power to spreadsheet applications. This paper illustrates the potential of these macros by presenting a macro spreadsheet solution to a difficult engineering problem: the transient surface wave profile for unsteady flow in a prismatic open channel as solved by the method of characteristics. Command macros, function macros, subroutine macros, formatting, interaction with the user, and data file usage are all involved in the program. The solution utilizes several separate, but interconnected, macro spreadsheets; this assists the user in debugging the program and in making future modifications. Key words: computers, spreadsheets, macro programming, open channel flow, method of characteristics.
Dealing with varying moments of inertia of girders in bridge analysis
Authors: Bakht Baidar , Jaeger Leslie G.
Published: August 2008

In many slab-on-girder bridges, especially those that are continuous over two or more spans, the moment of inertia of a girder varies significantly along the length of the bridge. This paper critically examines the practice of analyzing such bridges for load distribution by methods that make the assumption of constant longitudinal torsional and flexural rigidities. It is found that this practice may not be valid for those slab-on-girder bridges in which variations of the girder moments of inertia are very large.A recommended procedure is given for cases in which the variation in moment of inertia is not too severe. The procedure involves (a) the determination of total bending moments, treating the bridge as a beam of variable moment of inertia, and (b) the determination of an equivalent constant moment of inertia for beams of varying moment of inertia. Using this procedure the load distribution properties of the bridge can be realistically analyzed by those computer-based methods (e.g., orthotropic plate, finite strip, and semicontinuum methods) or manual methods (e.g., AASHTO and Ontario methods) that cannot directly take account of the variation of longitudinal flexural rigidity.The validity of the recommended procedure is established by comparing its results with those of the grillage analysis method that does take account of the variation of the girder moment of inertia. Key words: bridge analysis, girders, load distribution, slab-on-girder bridges.
Behaviour of headed studs in composite beams: push-out tests
Authors: Jayas B. S. , Hosain M. U.
Published: August 2008

This paper briefly summarizes the results of tests conducted on 18 full-size push-out specimens and 4 pull-out specimens. The objective of the project was to study the behaviour of headed studs in composite beams with ribbed metal decks perpendicular and parallel to the steel beam. The longitudinal spacing of the headed studs and the rib geometry of the metal decks were the principal experimental parameters.Five of the push-out specimens had solid concrete slabs, in five specimens the ribbed metal deck was placed parallel to the steel beam, and in the remaining eight specimens the metal deck was perpendicular to the steel beam. In most cases 38 mm deck and 16 × 76 studs were used.Test results obtained by the authors appear to indicate that with some exceptions the current Canadian Standards Association and Load and Resistance Factor Design codes are able to predict stud strength correctly for specimens with solid slabs and with parallel ribbed slabs only when failure occurs owing to stud shearing, i.e., when the studs are spaced sufficiently apart. It is recommended that these codes include a provision to check the possibility of concrete-related failures when the longitudinal stud spacing approaches or falls below six times the stud diameter for solid and parallel ribbed slabs.Stud pull-out was the principal mode of failure in the specimens with perpendicular ribbed metal decks. An equation recently proposed by Hawkins and Mitchell appears to underestimate the capacity for specimens with 38 mm deck. For specimens with 76 mm deck, their equation overestimates the stud capacity. The authors have proposed two separate but similar empirical equations for specimens with 38 and 76 mm deck. Key words: composite beam, headed stud, stud shear capacity, stud pull-out failure, minimum stud spacing, perpendicular deck, parallel deck.
Design of lightweight wooden floors to avoid human discomfort
Authors: Smith Ian , Chui Ying Hei
Published: August 2008

This paper gives "designer usable" methods for predicting the dynamical behaviour of lightweight wood-joist floors covered with semirigidly attached wood-based sheathings of materials such as plywood or waferboard. Included are methods for predicting natural frequencies and root-mean-square (rms) acceleration under a defined forcing function. It is proposed that this rms acceleration be the criterion for estimating user perception based tolerance of a projected design solution in the domestic setting. Case studies suggest that the economic cost of producing more rational designs is small. Consideration is, at this stage, limited to floors that are rectangular in plan and contain no openings nor intermediate support partitions. Suggestions are made as to methods of building floors with acceptable vibrational performances, together with recommendations for further research. Key words: floors, wood, vibrations, human tolerance, design method.
Un modèle pour l'infiltration dans les sols gelés tenant compte de la qualité de l'eau
Authors: Padilla Francisco , Gélinas Pierre
Published: August 2008

The infiltration of water in frozen soils is solved using finite element methods for the numerical solution of water flow, heat, and solute transport in one dimension. These equations are coupled for the solution of Stefan's problem for different conditions of ice in soils. The degrees of freedom of this problem are soil temperature, water pressure, and solute concentration. A model is proposed to simulate the presence and formation of ice lenses in unsaturated and saturated soils. Early results are very promising when compared to analytical solutions.Two extreme cases are considered in applications: very wet and very dry soils. Frost heave and other parameters seem to have been properly simulated. The present model considers special phenomena related to colloidal soils; nevertheless, a comparison with field data is required. Key words: frozen soils, frost heave, unsaturated zone, heat transport, mass transport, Stefan problem, finite elements, phase change.
Head recovery at submerged abrupt conduit outlets
Authors: Kells James A. , Smith C. D.
Published: August 2008

The question of an abrupt expansion in a pipeline from one diameter to a larger diameter is a classical problem dealt with in most undergraduate fluid mechanics texts. A problem not dealt with, but which is far more common in practice, is the abrupt expansion at the terminal end of a pipe where the flow expands into an open channel downstream. It is often assumed that the entire velocity head for the pipe flow is lost. This is not necessarily true. In this paper, the experimental study of an abrupt expansion into an open channel is reported. Several different channel shapes are used in an attempt to determine shape effect, if any. It is concluded that the primary variable affecting the head loss is the ratio of the upstream to downstream flow area, called the area ratio. Key words: abrupt expansion, conduit outlet, head recovery, head loss, area ratio.
The engineering significance of glacier ice-thrusting
Authors: Sauer E. Karl
Published: August 2008

Field evidence in Saskatchewan indicates that glaciotectonic processes result in a significant change in the shear strength properties of the sediments and the boundary conditions for the groundwater regime. Glacier ice-thrusting resulting in the deformation and shearing of bedrock and glacial sediments appears to be widespread throughout southern Saskatchewan and probably elsewhere where continental glaciers overran clay shale or weakly cemented bedrock. Theoretical considerations indicate that wherever a glacier is forced into compressive flow by physical features that tend to decrease flow downstream, shearing thrust planes develop in the ice causing brecciation, slickensides, overthrust faulting, and drag folding of sediments that have been carried up into the ice. The conditions required to produce this phenomenon include upslope movement of the glacier over a concave surface and net ablation in the glacier regime. Three examples of the engineering implications of this process are included where massive landslides were found and it was established that ice-thrusting had occurred. Criteria were then established that would enable geotechnical engineers to identify the presence of this phenomenon during site investigations.
Adfreeze strength of frozen sand to model piles
Authors: Parameswaran V. R.
Published: August 2008

Laboratory measurements of adfreeze strength of Ottawa fine sand to three different types of model piles under constant rates of loading are reported in this paper. Adfreeze strength, [Formula: see text]f, at peak load increased with increasing loading rate (i.e., rate of displacement of cross-head of the testing machine), İ, and followed a power law[Formula: see text]The maximum adfreeze bond strength developed with uncoated wood piles (B.C. fir and spruce). Concrete piles developed adfreeze bond strengths lower than wood but higher than steel and coated piles. Coatings (creosote, paint, etc.) reduced adfreeze bond strength considerably. In decreasing order of adfreeze bond strength, the piles rated as follows: uncoated B.C. fir, uncoated spruce, concrete, unpainted steel cylindrical and H-sections, creosoted B.C. fir, and, finally, painted steel pipe.
Time-dependent deformation of shaly rocks in southern Ontario
Authors: Lo K. Y. , Wai R. S. C. , Palmer J. H. L. , Quigley R. M.
Published: August 2008

Two methods of laboratory measurements of time-dependent deformations of rocks due to the relief of in situ stresses are described. Experiments were performed on specimens taken from seven rock formations in southern Ontario. It was found that some rock types exhibit considerable time-dependent deformation, generally consistent with observed field behaviour. In addition, the swelling behaviour of the shaly rocks is anisotropic and constituent layers of the same rock formation may possess very different swelling characteristics. Mineralogical tests performed showed that the observed swelling behaviours are related to the composition and clay fabric of the rock.For detailed analysis of the test results, a rheological model was employed to represent the time-dependent deformation. Model parameters for three rock types have been obtained.Because the tests are simple and inexpensive to perform, it becomes practical to carry out a large number of tests for the evaluation of potential problems due to time-dependent deformation.
Strip footing on weak clay stabilized with a granular trench or pile
Authors: Madhav M. R. , Vitkar P. P.
Published: August 2008

There are many field situations where at least a moderate increase in the bearing capacity in weak clays is desired. One of the solutions for such situations is stabilization by installing a granular pile or stone column using empirical designs. The plane strain version of a granular pile is a granular trench. In the present investigation a failure mechanism is postulated for the granular trench and analytical expressions are derived for the ultimate bearing capacity of footings on such stabilized soils. Bearing capacity factors are presented for various combinations of the parameters considered. From the present study it has been reaffirmed that a granular trench significantly reinforces weak clay deposits.
Changes in the plasticity of a sample of Champlain clay after selective chemical dissolution to remove amorphous material
Authors: Hendershot W. H. , Carson M. A.
Published: August 2008

Although the effect of amorphous compounds on the undisturbed strength of Champlain clay has received much attention, the role of this amorphous material in the behaviour of the sediment following remoulding has been virtually ignored. Selective dissolution procedures on remoulded specimens revealed that removal of up to 4% amorphous material, primarily iron and silicon compounds, was associated with small decreases in specific surface area and cation exchange capacity, and large decreases in liquid limit and plasticity in ex. Analysis of X-ray diffraction traces indicates some alteration of the crystalline components during NaOH–CBD dissolution, but little alteration occurred with the KOH–NH4Ox method, the procedure which achieved maximum extraction of Fe a d Si in this study. It is tentatively concluded that the presence of amorphous material may be responsible for much of the plasticity displayed by Champlain clay rock flour. As a corollary, natural variability in the content of amorphous material in Champlain clay may be correlated with regional and stratigraphic patterns of sensitivity.
Application of a rock buttress in the design of slopes of a strip coal mine adjacent to a highway
Authors: Ulusay R. , Yolerì M.F. , Doyuran V.
Published: August 2008

Eskihisar open pit mine, located at Yatagan, southwest Turkey, produces thermal coal for a power generating plant. As mining of strips advanced southwards, instability appeared to be highly critical due to the movements in the southeast wall slopes adjacent to the state highway running parallel to the pit boundary. This situation called for an immediate response to initiate a detailed geotechnical investigation program and to redesign the pit slopes. This paper outlines the most probable mode and mechanism of instability along the southeast wall, as well as field and laboratory studies, results of back analysis, discussion of the data requirements, and results of slope stability analyses performed to ensure adequate overall stability. The studies revealed that the most critical failures may occur along two or three planar surfaces, by combination of fault, bedding plane, and localized strata steepening adjacent to the fault, in multiplanar failure mode controlled by faulted blocks. The stability is sensitive to changes in length of the lower part of the basal sliding surface, as well as to the configuration and shear strength of black and highly plastic underclay. The effects of a buttress of intact rock and slope flattening on the stability are compared and discussed. Key words : back analysis, multiplanar failure, shear strength, slope stability, toe buttressing.
On the pullout resistance of geosynthetics
Authors: Fannin R.J. , Raju D.M.
Published: August 2008

Pullout tests are reported on geosynthetic test specimens embedded in a relatively dense, coarse sand sample. The tests are displacement controlled and are performed at different vertical effective stresses. Tests are reported for a smooth and textured geomembrane and for geogrids of a high and low junction strength. Behaviour is compared with an inextensible, rough sheet. Pullout resistance is governed by progressive tensile strain in the geosynthetic which is a result of relative displacement between it and the soil. Values of interface bond that are described by an interaction factor vary significantly and are stress dependent. Both types of geogrid and the textured geomembrane exhibit a similar response to loading at small displacement, and mobilize a much larger interaction factor than the smooth geomembrane. A rationale is suggested for selection of appropriate values in design. Key words : pullout testing, geogrid, geomembrane, interface friction, reinforced soil.
Equivalence of mesh- and fibre-reinforced shotcrete at large deflections
Authors: Kirsten H.A.D.
Published: August 2008

The object of the study was to determine whether extensively deflected mesh- and fibre-reinforced shotcrete as found in mines were equivalent. Full-size panel tests were accordingly carried out, from which it was concluded that uniformly distributed loading was marginally less severe than point loading, mesh reinforcement was superior to fibre reinforcement, Dramix fibre and Melt Extract fibre were similar in reinforcing characteristics, and 30–35 mm was an optimum fibre length. Consistency of fibre content could not be assured in the practical mining situation considered. A maximum content of about 1.5% could be obtained for fibre lengths not exceeding 35 mm. Owing to its greater flexibility, diamond mesh reinforced shotcrete was found to be preferable to fibre-reinforced shotcrete in excavations subject to squeezing conditions. In view of the difficulties associated with assuring the consistency of the fibre content in mining applications, it appears that the sophisticated attributes of fibre-reinforced shotcrete can only be effectively exploited in civil engineering applications in which quality assurance is subject to explicit contractual control. Key words : fibre reinforcement, shotcrete, mesh reinforcement, large deformation.
Uplift of model steel pipelines embedded in polycrystalline ice
Authors: Rajani B. , Morgenstern N.
Published: August 2008

The experimental behaviour of model pipelines embedded in polycrystalline ice is studied to improve the understanding of the behaviour of a chilled buried pipeline subjected to frost heave. Two model pipelines with slightly different radius to thickness ratios were subjected to prescribed displacement rates. Their behaviour was monitored until peak strains corresponding to current acceptable strain limits, often referred to as the wrinkling strains, were exceeded. The sizing of the model pipelines and experimental setup are described and detailed procedures on polycrystalline ice sample preparation are given. Representative core samples of polycrystallineice were tested to determine its elastic and creep properties. The observed and predicted responses of strain histories in the pipeline are compared and acceptable agreement between the responses is obtained. Key words : experimental behaviour, embedded model pipelines, polycrystalline ice, frost heave, uplift resistance, critical strain limits.
Load transfer for piles in sand and the critical depth
Authors: Altaee Ameir , Fellenius Bengt H. , Evgin Erman
Published: August 2008

The authors analyzed the results from a static loading test on a 11.0-m, intrumented, precast concrete pile and presented the findings in two earlier papers. The findings are here extrapolated to verify the dependability of applying the results and analysis methods to predict the detailed behavior of a similar test pile driven 5 m away from the first pile and to a 4.0 m deeper embedment. This paper offers conclusions drawn from the analyses of both piles with regard to residual load and resistance distribution. A primary result of the analyses is the indication that the critical-depth concept is not valid. For full-length piles, the critical-depth concept originates because of neglects in analysis of test data, such as omission of the residual load and testing-sequence history. For tests on short piles and laboratory studies of model piles, a critical depth appears as a result of neglect of the influence of shallow-depth variation of the earth pressure coefficient. Key words : instrumented piles, sand, loading test, residual load, load transfer, finite element, constitutive modelling, critical-depth concept.
Observed and calculated pore pressures and deformations induced by an earth balance shield
Authors: Yi X. , Rowe R. Kerry , Lee K.M.
Published: August 2008

The observed pore pressures and deformations induced by an earth balance shield used to construct the Furongjiang sewer tunnel in soft saturated ground in Shanghai, China, are briefly described. A numerical technique for predicting these pore pressures and deformations is outlined. This approach adopts a coupled viscoplastic-consolidation analysis to describe the time-dependent deformations and strain-hardening behaviour of the soil using parameters obtained from triaxial creep tests. A comparison is then made between numerical results and the results of field measurements, and it is shown that there is encouraging agreement between the calculated and observed response. Key words : tunnelling, finite element, settlements, viscoplastic model, consolidation, field measurement.
Verification and calibration studies for the new CAN/CSA-S472 foundations of offshore structures
Authors: Been K. , Clark J.I. , Livingstone W.R.
Published: August 2008

In June 1992, the Canadian Standards Association (CSA) published a code for the design, construction, and installation of fixed offshore structures. This code is relatively advanced in its application of limit states design to offshore structures. The part dealing with foundations is written as a performance standard. It does not specify resistance factors (or safety factors) to achieve the target reliability of the structure. Although limit states design is common practice among geotechnical engineers, the application of resistance factors is a problem. This paper describes some of the studies and conclusions reached by the Technical Committee in the development of the CSA foundations standard. As a first step, resistance factors were developed by calibration to conventional total factors of safety for the failure mechanisms considered. This approach has severe limitations. In particular, the applicability of safety factors developed for onshore practice or other offshore areas to the ice-dominated environment of Canadian offshore regions is questionable. In addition, many offshore structure designs include consideration of dynamic loading and scour or erosion problems that cannot be satisfactorily dealt with using factors of safety. An example of the problem of applying separate load and resistance factors for a bearing-capacity problem is given to show that load and resistance are not independent of each other. Because of the problems with development of resistance factors, the CSA foundations standard dictates that offshore structure designs include a risk analysis of the foundation system. A simple form of such an analysis for a caisson-retained sand structure is included in the paper. Key words : offshore structures, foundations, standard, safety, limit states design.
Rational design treatment of slides in overconsolidated clays and clay shales
Authors: Brooker Elmer W. , Peck Ralph B.
Published: August 2008

During the early part of the past century, engineers were repeatedly surprised by unforeseen movements of valley slopes on overconsolidated, flat-bedded clays and clay shales. Movements have occurred, and still persist, throughout the Cretaceous Sea area of North America. During the past 20 years the profession has been developed to the point where the element of surprise should not be an issue. However, historically, during construction of bridges and dams, intensive effort was required to moderate and control the movements. Research in the geotechnical community over the past 50 years has led to an understanding of the causes and treatment of the movements. Highly overconsolidated deposits are associated with coefficients of earth pressure at rest of about 2, induced by geologic activities such as erosion and glaciation. The horizontal forces that prevail are a major contributing factor to movement along depositional weak layers beside or beneath valleys. Overconsolidated clays display distinct peak and residual strength values. Progressive reduction of strength from the toe of a slope along a weak layer results in a global reduction of shearing resistance, finally leading to a factor of safety of unity. It has been the experience of the authors that the geologic details and hydrologic environment which prevail in most slides are complex and usually cannot be defined well enough to justify great effort in computational analyses. Nevertheless, evaluation of case records over the vast area of Cretaceous deposition with the aid of geomorphology, air photographs, and records of movements allows useful conclusions to be drawn, leading to a rational design philosophy. This review focuses attention on such a philosophy. Movements in slide areas are progressive or episodic. Often an historic slide area is dormant and may be reactivated by relatively minor construction activity. Other cases involve ground that is gradually reaching a global factor of safety of unity. Inherent in the design philosophy proposed is a decision whether to accept the movements and design the structures to tolerate them (passive design), or to restrain or stop the movements of the slide mass (aggressive design).This approach is described. Detailed and sophisticated computational analyses have been useful in supplementing an understanding of failure mechanisms. In practice, however, there has been an increasing tendency to turn to computer programs, sometimes quite elaborate, without adequate knowledge of geologic, hydrologic, and observational data. Often, if such data are collected and digested, very simple analyses may suffice for the design of preventive or remedial measures. Observations of active slide masses show that they most often move at a rate of about 100 mm/year. In these cases only simple analyses are justified in evaluating possible corrective measures. Key words : slides, clay, shale, overconsolidated, movements.
Mechanisms of massive failure for flowthrough rockfill embankments
Authors: Garga Vinod K. , Hansen David , Townsend D. Ronald
Published: August 2008

A modified wedge method for the analysis of the stability of a downstream slope of a flowthrough rockfill dam is presented. The results from this wedge analysis are compared with results from a conventional Bishop method of analysis, and both are compared with experimental measurements of the forces at incipient failure from model tests performed on simple granular embankments in hydraulic flumes. The proposed wedge method, based on a nonrotational failure mechanism, compared more favourably with experimental observations than did the Bishop method of analysis, based on a rotational failure mechanism. It is also concluded that the Bishop method is very conservative for the analysis of such rockfill slopes. Key words : rockfill embankment, slope failure, bursting forces, model slopes, non-Darcy flow.
Design of reinforced fill systems over voids
Authors: Agaiby Sherif W. , Jones Colin J.F.P.
Published: August 2008

Embankment fill structures are often laid on formations that may develop cavities during their life-span. The use of geosynthetic reinforcement to mitigate the consequences of the formation of such cavities provides an appealing solution to the problem. To properly analyse the problem of reinforced fill overlying cavities, the reinforcement–fill interaction has to be properly addressed and modelled for a realistic solution to be reached. Typically, this problem has been approached by researchers using limit-equilibrium methods. Limited continuum analyses results are available for the problem. This paper presents the results of a systematic parametric continuum analysis that was carried out to study this problem. The parameters that govern the behaviour of reinforced fill systems were identified and varied within their typical ranges. The objective of the study is to provide a comprehensive set of design charts that give insight into the behaviour of reinforced fill systems and highlight the effect of each of the parameters that govern this behaviour. The charts are presented in simple formats that aid the engineer to estimate the expected settlements, reinforcement tension, and width of affected zone for different conditions, as well as obtain a feel for the interaction taking place between the various elements of the system. Key words : reinforced fill, tension membranes, geosynthetics, coral formations, karstic formations, sinkholes.
Analysis of membrane action in reinforced unpaved roads
Authors: Burd H.J.
Published: August 2008

Polymer grid or geotextile reinforcement may be used to improve the performance of reinforced fill layers placed on soft ground. This paper is concerned with the mechanics and design of reinforced unpaved roads built over soft clay, which is a particular application of this reinforced soil technique. A discussion is given of the mechanics of reinforced unpaved roads for the case of a single application of a plane strain, monotonic load, and the design procedures that are currently available for this type of structure are reviewed. A new analytical design model is proposed. This new model is based on a membrane reinforcement mechanism and is appropriate for cases where large surface deformations are acceptable. Results obtained using this new model are shown to compare well with data obtained from previously published laboratory tests. The use of a finite element method to study this type of structure is described, and the results of finite element analysis are used to discuss the accuracy of the proposed analytical model. Key words : soil reinforcement, unpaved roads, membrane, finite elements, reinforcement mechanisms, foundations.
Distribution, origin, and hydraulic influence of fractures in a clay-rich glacial deposit
Authors: McKay L.D. , Fredericia J.
Published: August 2008

In the unconsolidated clay-rich glacial deposits underlying a site in southwestern Ontario, fractures and root casts greatly influence hydraulic conductivity and groundwater flow. The fractures are predominantly vertical and have visible oxidation staining from surface to a depth of 6 m. Root casts commonly occur along fracture surfaces in the upper 3 m, but can also occur as holes in apparently unfractured blocks. The fractures are believed caused mainly by dessication during past periods of low water table. This hypothesis is supported by a decrease in fracture density with depth and the presence of a stiff crust, presumably caused by desiccation-induced consolidation. The random pebble fabric and faint layering indicate deposition in a calm lacustrine environment, which precludes the possibility of the fractures having been caused by overriding ice. Fractures were found below the depth of oxidation staining (6 m) but most of these appear to have been caused by stress-relief due to the excavation and subsequent drying. In the upper 3 m the fractures and root casts are responsible for field-measured hydraulic conductivity values that are up to 3 orders of magnitude greater than measured in the laboratory for samples of the unfractured matrix. High values of field-measured hydraulic conductivity, seasonal head variations greater than 0.5 m, and high tritium content all persist below the depth of root casts, indicating that hydraulically conductive fractures do exist to depths of at least 6 m and possibly as great as 12–15 m, which is well below the depth of oxidation staining. However, there is some uncertainty in this assessment of the extent of hydraulically conductive fractures because of the sensitivity to small leaks in the piezometer installations. Key words : clay, glacial, fractures, desiccation, hydraulic conductivity.
The Edgerton landslides
Authors: Cruden D.M. , Thomson S. , Kim H.J. , Peterson A.E.
Published: August 2008

Observations over 20 years of three contiguous translational slides on the west wall of a 100 m deep valley in the Interior Plains document their evolution into advancing, composite, slow earth-flow earth-slides involving over a million cubic metres of displaced material. Colluvial deposits downslope of the apparent toes of the flows are moving. The reactivation of the abandoned slides in the Upper Cretaceous sedimentary rocks was likely triggered by years of higher than average precipitation following clearing of brush behind the crest of the slope. Back analysis is consistent with fully softened rock in the crowns of the slides and displaced materials at residual strength. Key words : landslide, rock-slide, earth-flow, earth-slide, Interior Plains.
Experiments on surface deformation arising from a subsurface fracture
Authors: Wang Gang , Dusseault Maurice B. , Pindera Jerzy T.
Published: August 2008

Laboratory model simulation of large-scale earth processes is rarely undertaken because of scale effects, nonlinearity, and questions of representativeness with respect to the real case. Hydraulic fractures generate distortion fields that can be measured with high precision both in the laboratory and in the field. A combination of field and laboratory data allows us to test our ability to measure displacements, make forward predictions, and invert real measurements; thus it is important to have some means of simulation, other than purely numerical simulation. This paper contains the results of a set of experiments on the surface deformation arising from a pressurized fracture, using laser holography and Fizeau interferometry of noncontacting techniques to precisely sample the displacement field above a scale model. The results are remarkably accurate and consistent, and compare reasonably well with analytical and numerical model predictions. The techniques have potential applications in geomechanics and geotechnical engineering for laboratory study of various linear and nonlinear problems. Key words : laboratory simulation, holographic, Fizeau interferometry, hydrofractures.
Détermination de la perméabilité non saturée des matériaux argileux à faible porosité
Authors: Robinet J.C. , Rhattas M.
Published: August 2008

The presence of impermeable natural or artificial clayey layers plays a fundamental role in protecting ground water from pollution. In the case of low porosity and partially saturated clays, the experimental determination of transfer coefficient is particularly difficult because of a considerable reduction in hydraulic head and of water–particle interactions that reduce the interstitial water mobility. Experimental work was carried out to obtain, in a simple way, the hydrodynamic characteristics of two clayey formations: Boom and Bassin Parisien. The hydraulic profiles were determined by soaking tests on 300 mm high clayey columns and the sorption–desorption isotherms were evaluated by the saline solution technique on several samples of both clays. The spatio-temporal analysis of the hydraulic profiles reveals the variations in isothermal diffusion coefficient according to the water content. In accordance with the hypothesis of local equilibrium, the sorption–desorption isotherms give the characteristic curve of each formation in a potential versus water content relationship. The total diffusivity combined with retention curves allows to calculate the permeability as a function of the saturation. Key words : clay, sorption–desorption isotherms, soaking tests, diffusion coefficient, permeability.
Negative skin friction from surface settlement measurements in model group tests
Authors: Ergun Mehmet Ufuk , Sönmez Devrim
Published: August 2008

Groups of model wood piles driven to end bearing through dense sand over soft clay were used to determine the relative settlement of the soil surface inside and outside the groups as the soil was compressed by air pressure. Square 30 mm piles at spacings of 2 to 6 times the pile width were used in groups of 3 × 3, 4 × 4, and 5 × 5. The results indicate that pile group effects were negligible at pile spacings at 5 to 6 pile widths. Key words : negative friction, model study, pile groups, sand.
PATTERN EXTRACTION FROM BAG DATABASES
Authors: DELGADO MIGUEL , RUIZ M. DOLORES , SÁNCHEZ DANIEL
Published: August 2008

Many databases in real life involve pairs of the form (item,quantity). This kind of data can be characterized using the theory of bags. We present a general framework for extracting useful knowledge from bag databases using different types of patterns. Here we present different approaches for the task of discovering fuzzy association rules and gradual dependencies in bag databases.
MATHEMATICAL PROGRAMMING APPROACH TO MULTIATTRIBUTE DECISION MAKING UNDER INTUITIONISTIC FUZZY ENVIRONMENTS
Authors: LI DENG-FENG , WANG YONG-CHUN
Published: August 2008

There exists little investigation on multiattribute decision making under intuitionistic fuzzy environments although both crisp and fuzzy multiattribute decision making have achieved a great progress. In this paper, multiattribute decision making problems using intuitionistic fuzzy sets are investigated and the TOPSIS is further extended to develop one new methodology for solving such problems. In this methodology, an interval fractional programming model is constructed on the basis of the relative closeness coefficient using the TOPSIS. Comprehensive evaluation of each alternative, which may be described as an intuitionistic fuzzy set or interval number, is calculated using two auxiliary mathematical programming problems derived from the interval fractional programming model proposed in this paper. Optimal degrees of membership for alternatives are calculated to determine their ranking order using the concept of likelihood based on the ranking method of interval numbers. Implementation process of the method proposed in this paper is illustrated with a numerical example.
ROBUST FUZZY REGRESSION ANALYSIS USING NEURAL NETWORKS
Authors: NASRABADI EBRAHIM , HASHEMI S. MEHDI
Published: August 2008

Some neural network related methods have been applied to nonlinear fuzzy regression analysis by several investigators. The performance of these methods will significantly worsen when the outliers exist in the training data set. In this paper, we propose a training algorithm for fuzzy neural networks with general fuzzy number weights, biases, inputs and outputs for computation of nonlinear fuzzy regression models. First, we define a cost function that is based on the concept of possibility of fuzzy equality between the fuzzy output of fuzzy neural network and the corresponding fuzzy target. Next, a training algorithm is derived from the cost function in a similar manner as the back-propagation algorithm. Last, we examine the ability of our approach by computer simulations on numerical examples. Simulation results show that the proposed algorithm is able to reduce the outlier effects.
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: Kreinovich V.
Published: August 2008

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to vladik@utep.edu, or by regular mail to: V. Kreinovich, Department of Computer Science, University of Texas, El Paso, TX 79968, USA.
Global Carbon Emissions in the Coming Decades: The Case of China
Authors: Levine Mark D. , Aden Nathaniel T.
Published: August 2008

China's annual energy-related carbon emissions surpassed those of the United States in 2006, years ahead of published international and Chinese forecasts. Why were forecasts so greatly in error and what drove the rapid growth of China's energy-related carbon emssions after 2001? The divergence between actual and forecasted carbon emissions underscores the rapid changes that have taken place in China's energy system since 2001. In order to build a more robust understanding of China's energy-related carbon emissions, this article reviews the role of economic restructuring, urbanization, coal dependence, international trade, and central government policies in driving emissions growth.
The Bacteriophage DNA Packaging Motor
Authors: Rao Venigalla B. , Feiss Michael
Published: August 2008

An ATP-powered DNA translocation machine encapsidates the viral genome in the large dsDNA bacteriophages. The essential components include the empty shell, prohead, and the packaging enzyme, terminase. During translocation, terminase is docked on the prohead's portal protein. The translocation ATPase and the concatemer-cutting endonuclease reside in terminase. Remarkably, terminases, portal proteins, and shells of tailed bacteriophages and herpes viruses show conserved features. These DNA viruses may have descended from a common ancestor. Terminase's ATPase consists of a classic nucleotide binding fold, most closely resembling that of monomeric helicases. Intriguing models have been proposed for the mechanism of dsDNA translocation, invoking ATP hydrolysis-driven conformational changes of portal or terminase powering DNA motion. Single-molecule studies show that the packaging motor is fast and powerful. Recent advances permit experiments that can critically test the packaging models. The viral genome translocation mechanism is of general interest, given the parallels between terminases, helicases, and other motor proteins.
Impedance analysis of renal vascular smooth muscle cells
Authors: Balasubramanian Lavanya , Yip Kay-Pong , Hsu Tai-Hsin , Lo Chun-Min
Published: August 2008

Impedance of renal vascular smooth muscle cells (VSMCs) cultured on microelectrodes was measured by electric cell-substrate impedance sensing. Changes in measured impedance as a function of frequency were compared with the calculated values obtained from an extended cell-electrode model to estimate the junctional resistance, distance between the ventral cell surface and the substratum, and apical and basolateral membrane capacitances of renal VSMCs. This cell-electrode model was derived to accommodate the slender and rectangular shape of VSMCs. The calculated changes in impedance ( Zcal) based on the model agreed well with the experimental measurement ( Zexp), and the percentage error defined as |( Zcal − Zexp)/ Zexp| was 1.0%. To test the sensitivity of the new model for capturing changes in cell-cell and cell-substrate interactions induced by changes in cellular environment, we then applied this model to analyze timpedance changes induced by an integrin binding peptide in renal VSMCs. Our result demonstrates that integrin binding peptide decreases junctional resistance between cells, increases the distance between the basolateral cell surface and substratum, and increases the apical membrane capacitance, whereas the basolateral membrane capacitance stays relatively stable. This model provides a generic approach for impedance analysis of cell layers composed of slender, rectangular cells.
Radical-free biology of oxidative stress
Authors: Jones Dean P.
Published: August 2008

Free radical-induced macromolecular damage has been studied extensively as a mechanism of oxidative stress, but large-scale intervention trials with free radical scavenging antioxidant supplements show little benefit in humans. The present review summarizes data supporting a complementary hypothesis for oxidative stress in disease that can occur without free radicals. This hypothesis, which is termed the “redox hypothesis,” is that oxidative stress occurs as a consequence of disruption of thiol redox circuits, which normally function in cell signaling and physiological regulation. The redox states of thiol systems are sensitive to two-electron oxidants and controlled by the thioredoxins (Trx), glutathione (GSH), and cysteine (Cys). Trx and GSH systems are maintained under stable, but nonequilibrium conditions, due to a continuous oxidation of cell thiols at a rate of about 0.5% of the total thiol pool per minute. Redox-sensitive thiols are critical for signal transduction (e.g., H-Ras, PTP-1B), transcription factor binding to DNA (e.g., Nrf-2, nuclear factor-κB), receptor activation (e.g., αIIbβ3 integrin in platelet activation), and other processes. Nonradical oxidants, including peroxides, aldehydes, quinones, and epoxides, are generated enzymatically from both endogenous and exogenous precursors and do not require free radicals as intermediates to oxidize or modify these thiols. Because of the nonequilibrium conditions in the thiol pathways, aberrant generation of nonradical oxidants at rates comparable to normal oxidation may be sufficient to disrupt function. Considerable opportunity exists to elucidate specific thiol control pathways and develop interventional strategies to restore normal redox control and protect against oxidative stress in aging and age-related disease.