bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion transport in silver–lead–borate glass and evidence of ion association
Authors: Kumar Ajay , Shaju K. M. , Chandra Suresh
Published: April 2011

Silver-ion transport in a 60AgI–(30 – x)Ag2O–xPbO–10B2O3 glass system is established using various experimental techniques viz. X-ray diffraction, differential scanning calorimetry, Wagner's polarization method, the E.M.F. method, complex impedance spectroscopy, transient ionic-current measurement, and optical microscopy. The glass formation is limited to x ≤ 6 mol%. The addition of PbO modifies the conductivity as a result of the increase in the ionic mobility and the decrease in the charge carrier concentration due to the formation of more nonbridging oxygen-containing functional groups. From the study of the temperature dependence of the electrical conductivity and the ionic mobility, a decrease in the charge carrier concentration is also observed with increasing temperature. To explaining this, two possible types of ion-association mechanisms are proposed viz. (i) self-association and (ii) network association.
Mechanics of a charged particle on the Kaluza–Klein background
Authors: Vatsya S. R.
Published: April 2011

The path-integral method is used to derive a generalized Schrödinger-type equation from the Kaluza–Klein Lagrangian for a charged particle in an electromagnetic field. The compactness of the fifth dimension and the properties of the physical paths are used to decompose this equation into its infinite components, one of them being similar to the Klein–Gordon equation.
Optical phonons polarized along the c axis of YBa2Cu3O6+x, for x = 0.5 → 0.95
Authors: Homes C. C. , Timusk T. , Bonn D. A. , Liang R. , Hardy W. N.
Published: April 2011

The c-axis polarized phonon spectra of single crystals of YBa2Cu3O6+x, were measured for the doping range x = 0.5 → 0.95, between 10 and 300 K. The low background electronic conductivity, determined by Kramers–Kronig analysis of the reflectance, leads to a rich phonon structure. With decreased doping the five normally-active B1u modes broaden and the high-frequency apical-oxygen mode splits into two components. We associate the higher of these with the two-fold coordinated copper "sticks". The 155 cm−1 low-frequency mode, which involves the apical and the chain oxygens, splits into at least three components with decreasing doping. Some phonon anomalies that occur near Tc in the highly doped material occur well above Tc in the oxygen-reduced systems. An unusual broad phonon band develops in the normal state at ≈ 400 cm−1, which becomes more intense at low doping and low temperatures, borrowing oscillator strength from apical- and plane-oxygen modes resulting in a major transformation of the phonon spectrum below ≈150 K.
Relaxation and aging in lattice glasses
Authors: Walton D.
Published: April 2011

A sequential relaxation model for the susceptibility of site-diluted Ising systems is described. It is shown that the model, which yields an excellent fit to experimental results for the real part of the ac susceptibility of the site-diluted two-dimensional Ising spin glass, Fe0.4Mg0.6Cl2, predicts a change in susceptibility with time during aging that is confirmed by experiments on other spin glasses and the orientational glass KBr0.5CN0.5.
Charge transfer in the presence of a radiation field
Authors: Li S -M , Khou J -G , Zhou Z -F , Chen J , Liu Y -Y
Published: April 2011

In the first Born approximation, the dressing modification in laser-assisted charge exchange collision is investigated. The crosssections for electron capture by a proton from dressed atomic hydrogen and dressed helium targets are calculated within awide energy range. Theoretical results show that with impact energy increasing, the dressing effect leads to increasingly significant cross-section modifications. The modified capture cross sections are increasing functions of the ratio of laser strength to frequency. PACS Nos.: 34.50.Rk; 34.70.+e; 32.80.Wr; and 34.90.+q
Lyapunov and marginal instability in Hamiltonian systems
Authors: Grindlay J
Published: April 2011

The variational equations and the evolution matrix are introduced and used to discuss the stability of a bound Hamiltonian trajectory. Singular-value decomposition is applied to the evolution matrix. Singular values and Lyapunov exponents are defined and their properties described. The singular-value expansion of the phase-space velocity is derived. Singular values and Lyapunov exponents are used to characterize the stability behaviour of five simple systems, namely, the nonlinear oscillator with cubic anharmonicity, the quasi-periodic Mathieu equation, the Hénon-Heilesmodel, the 4+2 linear chain with cubic anharmonicity, and an integrable system of arbitrary order.PACS Nos.: 03.20, 05.20
Cyclic liquefaction of loose gassy sand
Authors: Grozic J LH , Robertson P K , Morgenstern N R
Published: April 2011

Gas can be found in many soils, but none more common than in seabed soils. Gas-charged sediments are known to be widely distributed throughout the world's oceans. Numerous research programs have studied saturated soil response to cyclic loading; however, little is known about the behavior of gassy soils subjected to cyclic loading. The response of loose gassy specimens subjected to cyclic loading was studied in a laboratory program. Triaxial tests were performed on specimens of reconstituted Ottawa sand prepared to various gas contents and densities. The specimens were consolidated and then sheared under undrained cyclic loading. Gas content was measured at the beginning and end of each test using time domain reflectometry. The response of the gassy specimens has been shown to be influenced by the soil state and grain characteristics and the intensity, duration, and frequency of the cyclic loading. The propensity of a soil to liquefy is represented by a cyclic resistance ratio, defined as the cyclic stress ratio to cause liquefaction, or to cause a specified amount of strain. The results of this laboratory program show that the cyclic resistance ratio increases as gas content and density increase. The laboratory study demonstrates that the cyclic liquefaction potential of a soil is reduced by the addition of gas; however, soils containing some gas may still experience cyclic liquefaction provided they are sufficiently loose.Key words: triaxial testing, cyclic liquefaction, Ottawa sand, gassy, unsaturated.
Electrokinetic sedimentation of contaminated Welland River sediment
Authors: Buckland D G , Shang J Q , Mohamedelhassan E
Published: April 2011

An experimental study on electrokinetic sedimentation of contaminated sediment is conducted. The sediment dredged from the Welland River in Ontario is heavily contaminated by metals, oil, and grease as a result of industrial activities over past decades. Characterization of the sediment is presented, followed by descriptions of the sedimentation columns used in the experiments and testing procedure. The application of electrokinetics on the Welland River sediment suspensions significantly increases the free settling velocity (up to 110%) and final solid concentration (up to 33%) and reduces the coefficient of sedimentation (up to 111%) and overall sedimentation time (up to 50%). These changes are functions of the initial solid concentration and applied electric field intensity. Based on the evaluation of all influencing factors, it is concluded that a continuous dc current generates better performance than intermittent current and electrokinetic sedimentation is more effective than chemical coagulation. All other conditions being equal, the combined application of electrokinetics and FeCl3 generated the best dewatering effect. The electrokinetic treatment generates pH changes ranging from pH 6.0 at the anode to pH 9.4 at the cathode which will generate a negligible environmental impact, as most metal contaminants will not be released to water in this pH range.Key words: electrophoresis, electrokinetics, sedimentation, contaminated sediment, waste management.
The effects of organic fluids on physicochemical parameters of fine-grained soils
Authors: Kaya Abidin , Fang Hsai-Yang
Published: April 2011

Researchers have shown that properties of fine-grained soils such as hydraulic conductivity change significantly when the pore fluid is replaced with organic liquids. In general, such changes have been reported as a function of the dielectric constant of the pore fluid and attributed to changes in soil structure. However, mechanisms causing changes in soil structure are yet to be understood. In this paper, the physicochemical properties of kaolinite, bentonite, and a local soil are determined as a function of the dielectric constant of pore fluids to evaluate the mechanisms causing changes in soil structure and, in turn, hydraulic conductivity. The physicochemical parameters determined in this study are cation exchange capacity (CEC), zeta potential (ζ), surface charge density, pore-size distribution, and Atterberg limits. Results show that physicochemical properties change as the dielectric constant of the pore fluid changes, such that as the dielectric constant of the pore fluid approaches that of the soil, the repulsive and attractive forces diminish; yet, there is a net increase in the attractive forces, causing aggregation of the particles. Based on the results of this study, it is suggested that as repulsive forces decrease the soil particles tend to flocculate and form aggregates due to attractive forces among particles, leading to a net increase in the effective flow area, resulting in increased hydraulic conductivity of the soil - pore fluid system.Key words: fine-grained soils, diffuse double layer, attractive forces, physicochemical parameters, CEC, zeta potential.
Interpretation of axial Statnamic load test using an automatic signal matching technique
Authors: Naggar M Hesham El , Baldinelli Michael JV
Published: April 2011

The Statnamic (STN) load test is characterized by a relatively long duration and low pile velocity and acceleration compared with the dynamic load test. The estimation of the static capacity of piles and their static performance characteristics from dynamic loading tests usually requires a signal matching process. In this process, the soil parameters are varied until an acceptable match between the computed and measured responses is achieved. The soil properties obtained are then used to characterize the static behaviour of the pile. In this paper, an approach is presented to analyze the response of flexible and rigid piles during the STN load test. In this approach, a one-dimensional model is used to represent the pile-soil system accounting for nonlinear soil behaviour, slippage at the pile-soil interface, and energy dissipation through wave propagation and different types of damping. The postpeak resistance of certain types of soils is also considered in the analysis. An automatic matching technique (AMT) was developed to facilitate the signal matching process for the analysis of pile response during the STN load test. The proposed AMT has several advantages, including reducing the bias in the results due to the initial selection of the soil parameters; increasing the accuracy and reliability of computed pile capacity; and reducing computational time, thus allowing for the analysis of the test results in the field. It is then possible to compute the pile capacity and make a timely decision on its suitability. The proposed approach was used to analyze the results of six STN load tests, and the comparison between the measured and computed results was good.Key words: piles, Statnamic, pile load test, signal matching, transient load, capacity.
Ground sampling program at the CANLEX test sites
Authors: (Fear) Wride C E , Hofmann B A , Sego D C , Plewes H D , Konrad J -M , Biggar K W , Robertson P K , Monahan P A
Published: April 2011

One of the primary objectives of the Canadian Liquefaction Experiment (CANLEX) project was to develop and evaluate undisturbed sampling techniques as part of the overall goal to focus and coordinate Canadian geotechnical expertise on the topic of soil liquefaction. Six sites were selected by the CANLEX project in an attempt to characterize various deposits of loose sandy soil. The sites consisted of a variety of soil deposits, including hydraulically placed sand deposits associated with the oil sands industry, natural sand deposits in the Fraser River Delta, and hydraulically placed sand deposits associated with the hard-rock mining industry. At each site, a target zone was selected and various methods of ground sampling were performed. These included ground freezing and sampling, fixed piston tube sampling, Christensen double-tube core sampling, large-diameter sampling using the Laval sampler, and sonic (rotary-vibratory) continuous coring. Ground freezing and sampling was performed at all six sites; the other methods were used at only some sites. Geophysical (gamma-gamma) logging was also performed in boreholes near the freeze pipe to independently measure in situ void ratios. This paper describes the techniques used in the ground-freezing and various sampling programs and presents a summary of the results. Comparisons of void ratios measured for various types of samples and using geophysical logging are also made.Key words: CANLEX, ground freezing, sampling, geophysical logging, void ratio.
Influence of compaction conditions on pore-size distribution and saturated hydraulic conductivity of a glacial till
Authors: Watabe Y , Leroueil S , Le Bihan J -P
Published: April 2011

The paper examines the hydraulic conductivity of a nonplastic till from northern Quebec. It is shown that the hydraulic conductivity is strongly influenced by the compaction degree of saturation, and the variation of hydraulic conductivity with void ratio is influenced by compaction conditions. Determination of pore-size distributions and microphotographs provide evidence that changes in hydraulic conductivity are related to the fabric of the compacted specimens and macroporosity developing when the soil is compacted at degrees of saturation less than that at the optimum.Key words: till, hydraulic conductivity, microfabric.
Alternative method of determining resilient modulus of subbase soils using a static triaxial test
Authors: Kim Dong-Soo , Kweon Gi-Chul , Rhee Suckkeun
Published: April 2011

The cyclic test for the determination of resilient modulus (MR) is often too complex and time-consuming to be applicable on a production basis. Therefore, the development of a simple and reliable alternative MRtesting technique is essential for the application in the mechanistic design of a flexible pavement system. Seven disturbed subbase soils were collected from the actual pavement projects for testing. To evaluate the effect of particle size on MR, standard MRtests with various maximum particle sizes and specimen diameters were performed using three subbase soils. The resilient moduli determined from various specimen sizes with the same particle-size distribution were almost identical. However, the value of the slope parameter k2in the bulk stress model was constant, but the value of k1increased with a decrease in maximum particle size. The effects of mean effective stress, loading frequency, and number of loading cycles on modulus were evaluated from torsional shear (TS), triaxial (TX), and MRtests. The alternative MRtesting procedure using the static TX test was proposed considering deformational characteristics of subbase soils. The predicted MRvalues from the proposed method matched well with those determined by the standard MRtest, showing the capability of the proposed method for determining MR.Key words: resilient modulus (MR), alternative MRtest, subbase soils, triaxial compression test, deformational characteristics, particle size.
Estimation of liquefaction-induced horizontal displacements using artificial neural networks
Authors: Chiru-Danzer M , Juang C H , Christopher R A , Suber J
Published: April 2011

In the present study, artificial neural network (ANN) models based on field performance data are developed for predicting liquefaction-induced horizontal displacements. A database consisting of 443 measurements of horizontal displacements forms the basis for ANN modeling and analysis. The ANN model resulted in predictive capabilities that surpass those of published methods. A sensitivity analysis of the ANN model is conducted to evaluate the effect of each individual input variable on the calculated horizontal displacement. The newly developed ANN model is compared with and shown to be more accurate than other existing methods in predicting liquefaction-induced horizontal displacements.Key words: liquefaction, artificial neural networks, lateral spreading.
The equivalence of a jointed shield-driven tunnel lining to a continuous ring structure
Authors: Lee K M , Ge X W
Published: April 2011

This paper presents a new method of determining the correction factor to approximate a jointed, shield-driven tunnel lining as a continuous ring structure under plane strain conditions. An earth pressure distribution pattern is proposed which is developed based on the long-term behavior of shallow tunnels constructed in soft clays as observed in the field. The "force method" was used to determine the internal forces and displacements of jointed, shield-driven tunnels. Either the vertical or the horizontal displacement of the tunnel lining can be used as a common matching parameter. Factors such as joint stiffness, soil resistance, joint distribution, number of joints, and tunnel geometry can be considered by the proposed method. Simplified design equations for the estimation of equivalence factors are also proposed for the typical tunnel lining geometry of urban subway tunnels. The proposed equivalence method was evaluated by comparing it with the results of laboratory tests.Key words: shield-driven tunnel, jointed segmental lining, effective bending rigidity ratio, equivalence factor, lining internal force, earth pressure distribution.
A method for locating critical slip surfaces in slope stability analysis
Authors: Zhu Da-Yong
Published: April 2011

This paper presents a new method for locating critical slip surfaces of general shapes in slope stability analysis. On the basis of the principle of optimality, along with the method of slices, a critical slip field (CSF) in a slope is postulated which consists of a family of slip surfaces having maximum values of unbalanced thrust forces at exit points on the slope face. A numerical procedure is developed for constructing the CSF. The critical slip surface having minimum factor of safety is included in the CSF. All the critical slip surfaces corresponding to all of the exit points are thus determined consecutively, resulting in a global critical slip field (GCSF) which exhibits both global and local slope stability. Comparisons with other methods are made which indicate the high efficiency and accuracy of the proposed approach. Applications of the proposed method to two case examples are given, the results of which demonstrate its applicability to practical engineering.Key words: slope, stability, analysis, factor of safety, critical slip field.
A case history of shallow sloughing within cut slopes of an irrigation canal in salt-rich clayey colluvium
Authors: Globa R S , Barbour S L
Published: April 2011

An investigation and remediation of instability along cut slopes of an irrigation canal in salt-rich clayey colluvium in southern Alberta is described. Random sloughing of the canal side slopes began to occur 2 years after construction over a 7500 m length of canal and was nearly continuous over a 2500 m length 3 years later. The sloughs are shallow seated and most had the appearance of a "mud" flow. Soil salinity also developed along the canal slopes due to capillarity and evaporation. Failure of the clay slopes in the cut sections is attributed to swelling, dispersion, and softening of the subgrade due to exposure of the salt-laden clays to fresh water. In contrast, 600 m of salt-rich clayey colluvium compacted as a clay liner on the canal side slopes showed no evidence of sloughing and salt loading after 9 years of service. Good soil compaction inhibited softening and slope instability in these salt-rich soils. Results from detailed site investigations and observations, and the interplay of soil chemistry and geology, facilitated the selection of a satisfactory method of repair. Repairs consisted of reconstructing 2500 m of canal by overexcavating the canal subgrade and replacing those soils with compacted soil.Key words: clays, salts, dispersive, sloughing, salinity, compaction.
Empirical settlement predictions in overconsolidated Champlain Sea clays
Authors: Morissette Luc , St-Louis Michel W , McRostie Gordon C
Published: April 2011

Using settlement observations published for several embankments on marine clays of the Champlain Sea, an empirical model is proposed to estimate long-term settlements. The effect of the overconsolidation ratio is taken into consideration within the model. Footing- and raft-type foundation cases are considered to give guidelines when using the model for these foundation types. A specific embankment resting on a foundation of high water content clay with a high compressibility index demonstrates that a correction factor should be applied under these conditions.Key words: settlement, embankment, Champlain Sea clay, consolidation, empirical model.
Deterministic and probabilistic treatments of multiplanar pitwall failures at Himmetoglu (Turkey) coal mine
Authors: Tuncay Ergün , Ulusay Resat
Published: April 2011

This paper describes the investigation of a large and progressive slope failure in the south sidewall of the Himmetoglu coal mine in northwest Turkey. A number of slope instabilities leading to interruptions in mining have been experienced at the mine. Geotechnical investigations consisted of structural mapping, observations of instabilities, review of detailed groundwater information, long-term monitoring of slope movement, and back-analysis of the various failure modes. Deterministic and probabilistic approaches based on the limiting-equilibrium method were employed to examine various slope profiles and excavation sequences for achieving better stability conditions. Analysis of the movement monitoring records and geotechnical information indicated that the failure of the south sidewall slope developed by a combination of sliding along the bedding planes in the hanging wall and faults in the mode of multiplanar sliding. The movement history and the results from the back-analysis of the failures revealed that the stability of the slope was highly sensitive to changes in the length of the lower part of the sliding surface, and the shear strength reduced to residual values along the discontinuity surfaces 8-10 m above the coal seam at the time of failure. The results of the analysis both from deterministic and probabilistic approaches suggest that an excavation sequence consisting of a number of stripping stages from the uppermost benches and advancing to the toe of the slope may provide the resistance to stabilize the overall slope. Simple and preliminary economic assessments based on the overburden costs in conjunction with the deterministic and probabilistic approaches are briefly discussed.Key words: back-analysis, deterministic approach, Himmetoglu coalfield, monitoring, multiplanar failure, probabilistic approach, shear strength, slope stability.
A Study of a Large Compacted Clay Embankment-Fill Failure
Authors: Insley Alan E
Published: April 2011

The paper describes the failure during construction of a proposed 70 ft. high railway embankment fill. The fill was built of a uniform clay of medium plasticity which was used at an average moisture content of 3 per cent greater than had been provided for in the design. The fill failed under its own weight when it reached a height of 55 feet.In order to assist in the design of stabilizing works three test holes were drilled in the fill and soil samples recovered. Properties of field compacted and laboratory compacted soil samples are compared. The age of both types of samples is shown to have a significant effect on the test results.Both total and effective stress analyses of the embankment at failure have been performed using the laboratory values of soil strength. The total stress analysis gives a safety factor of 1.0 at failure whereas the effective stress analysis gives a safety factor of 1.2. The hazards of choosing the correct value of laboratory shear strength for the total stress analysis are discussed.
Settlement of Mat Foundation on Thick Stratum of Sensitive Clay
Authors: Casagrande L , Firing P , Schoof G , Tttrcke E John
Published: April 2011

Foundation investigations for an industrial plant on a thick stratum of preconsolidated, sensitive clay are presented. In spite of the fact that the effective stresses in the clay caused by the building load remained below the average preconsolidation pressure of the clay, the settlement of the buildings locally appreciably exceeded the anticipated order of magnitude. It is shown that a drop in the groundwater level by a few feet would result in the effective stresses exceeding the preconsolidation pressure within the upper portion of the clay stratum. With such an assumption, the consolidation would not be governed by the very flat recompression branch of the consolidation curve, but in part also by the steep virgin compression branch of the consolidation curve. It is concluded that, when dealing with preconsolidated, sensitive clays, the total effective stresses caused by a proposed structure should be kept within a safe margin below the average preconsolidation pressure in order to make provision for any unforeseen load increase such as might arise from a drop in the groundwater elevation.
The Corrosiveness of Muskeg Waters: A Review
Authors: MacFarlane L C
Published: April 2011

Muskeg waters are generally acidic and potentially corrosive to concrete and metal structures. The amount of dissolved salts and free carbon dioxide in the water is an important factor in its aggressive attack on concrete. Although pH measurements are not the only criterion of aggressiveness, they are a reasonable indication in many instances of potential severity. A good defence against an aggressive environment is a high quality, very dense concrete. High alumina concrete and air-entraining agencies provide further protection in extremely aggressive environments. Surface treatments of concrete have not proved to be very successful over a long period of time.Corrosion of metals in a muskeg environment is an electrochemical action; the type and rate of corrosion are functions of the property of the metal as well as the soil and water conditions. Factors such as dissolved salts, pH, total acidity, resistivity, aeration, and presence of anaerobic bacteria influence corrosion. Optimum protection to metals in an aggressive environment is provided by a combination of a surface coating and cathodic protection.
Predicting Unfrozen Water Contents in Frozen Soils
Authors: Dillon Howard B , Andersland O B
Published: April 2011

A relationship between temperature and certain soil properties including specific surface area, activity ratio, and the expandable clay lattice, is presented for predicting the unfrozen water content of frozen soils. Data on experimental calorimetric determinations for ice content of two frozen clays and a frozen silty clay are given. Predicted unfrozen water contents are compared with experimental values for eleven soils with good agreement in all cases. Temperatures close to and above the freezing point depression of the soil are excluded. Knowledge of the unfrozen water content in frozen soils permits a more realistic approach to a variety of problems in frozen soil mechanics.
Some factors affecting compacted clay swelling
Authors: Yevnin A. , Zaslavsky D.
Published: April 2011

Volume change after saturation was determined on specimens of a statically compacted clay soil. It was found that density after swelling increases linearly with increasing initial density, initial moisture content, and increasing logarithm of applied loading pressure. An empirical equation with five coefficients and a constant, found with the aid of a computer, represents the results with a coefficient of correlation close to 1. An equation for the swelling pressure was also obtained from this equation. Results of specimens which consolidated did not fit the lines obtained for swelling. The relationships obtained were explained by the influence of particle reorientation and moisture content on swelling tendency.
Transient temperature distribution in insulated pavements—predictions vs. observations
Authors: Ho D. M. , Harr M. E. , Leonards G. A.
Published: April 2011

Based on a finite difference technique, computer programs have been developed whereby temperature variations in layered systems as a function of position and time may be computed under conditions of both one- and two-dimensional heat flow by conduction. No limitations are imposed on the number of layers, or on the form of the initial and boundary temperature conditions. Variations in thermal properties of the materials with temperature and location, and the non-linear relation between amount of water frozen as a function of temperature, are directly taken into account. Comparison of predictions with actual measurements demonstrate that accurate forecasts of temperature distributions as a function of time can be made when prevailing ambient conditions are known. Even if the site conditions can be evaluated only approximately sufficiently reliable predictions can be made for design purposes.
A tunnel roof failure in till
Authors: Matheson David S.
Published: April 2011

A failure of an unsupported section of a tunnel roof in till is described. The failure was preceded by the formation of longitudinal cracks in the tunnel roof and consisted of a series of falls of discrete blocks from the roof. The presence of sand lenses in the till appears to affect adversely the stability of the tunnel roof.
Spread footings on "reinforced" soil
Authors: Kuzmanović B. O. , Balla À.
Published: April 2011

In case of foundations on thick layer of weak or medium quality, short tubes or sheet-pile mantles encompassing the footings and of small wall-thickness driven into the ground can increase considerably the bearing capacity of the soil. The footings are in this way artificially deepened and the horizontal displacements of the subsoil within the tube or mantle are confined. Thus, only vertical compression is possible within the "reinforcement" of the soil. The paper produces theoretical solution for the stress conditions and vertical settlement. Two illustrative examples with model tests are also included.
Geographical Distribution of Post-Glacial Slumping in Southern Alberta
Authors: Beaty C. B.
Published: April 2011

Study of more than 100 post-glacial landslides of the slump variety in the plains of southern Alberta reveals that a remarkably high proportion (87%) has occurred on slopes of northerly, northeasterly, easterly, and southeasterly aspect. While lithologic and engineering properties of the Upper Cretaceous sediments and Pleistocene glacial mantle of this area undoubtedly have conditioned the geological behavior of the earth materials affected, it is here contended that microclimatic factors favoring the accumulation and retention of snow on slopes of particular exposure, or aspect, have more strongly controlled the geographical distribution of the observed slumps. Reasons for and consequences of microclimatic control are discussed.
Consolidation of Soils Under Cyclic Loading
Authors: Wilson N. E. , Elgohary M. M.
Published: April 2011

A theoretical solution for the progress of consolidation of a saturated soil layer subjected to cyclic loading is obtained.Consolidation, proceeding inwards from the drainage face, is slower than consolidation under an equivalent sustained loading because positive and negative pore-water pressures, produced during the loaded and unloaded portion of the cycle, cause flow of water from and into the soil. An equilibrium, or finalized, consolidation ratio is reached which is dependent on the pattern of loading cycle; it is not possible to reach 100% consolidation under cyclic loading.
Directional Variation in Undrained Shear Strength and Fabric of Winnipeg Upper Brown Clay
Authors: Loh A. K. , Holt R. T.
Published: April 2011

The undrained shear strength and the fabric of a lacustrine clay from Winnipeg, Manitoba, have been determined with respect to the orientation of the natural bedding plane. Unconfined compression tests show that both the undrained shear strength and the normalized secant modulus of 'undisturbed' clay were anisotropic. The fabric, determined by X-ray diffraction analysis, was also found to be anisotropic in the 'undisturbed' samples. The same material in the remolded condition was isotropic with respect to both undrained shear strength and fabric. Observations of the failure plane have been used to calculate the resolved shear stress on the failure plane, and the results agree qualitatively with prediction, according to Jaeger's weak plane hypothesis. The variation of undrained shear strength with orientation may be due to (1) the clay fabric and (2) stratification, although these two factors may be interdependent.
Mud Creek Bridge foundation movements
Authors: Bozozuk M.
Published: April 2011

A 400 ft (122 m) long, five-span concrete bridge over Mud Creek, supported on end bearing steel piles, was instrumented to measure horizontal movements of its foundations. Fifteen years of observations show that the abutments and piers have moved downslope and rocked back and forth through a small vertical angle about their bases. The net convergence of the abutments is about 4 cm. The horizontal movements were caused by soil creep in the marine clays of the steep valley slopes. The change in verticality of the piers was attributed to the expansion and contraction of the bridge deck due to seasonal temperature variations. The steel end bearing batter piles were ineffective in maintaining the piers and abutments in their original positions.
Geotechnical aspects of coal waste embankments
Authors: Holubec Igor
Published: April 2011

The expanding consumption of energy has created new demands for coal and increasing activity in the coal mining industry. However, the mining of coal is accompanied by coal wastes which are dumped in the form of coal waste embankments. The present concern for safety and the environment requires an analysis of the geotechnical problems associated with the construction of these embankments to assure acceptable engineering design. This paper discusses the properties of the coal wastes and the behaviour of coal waste embankments which differ from the common earth embankments that the geotechnical engineer has to deal with.
Model tests on anchored walls retaining overconsolidated sands
Authors: Anderson W. F. , Hanna T. H. , Shah S.A.
Published: April 2011

This paper reports the findings of two series of tests which are part of a continuing study into the behaviour of laboratory scale anchored retaining walls supporting cohesionless soil. In each test field construction was simulated and the behaviour of the wall, anchors, and soil was monitored. The behaviour of a wall supported by horizontal anchors has been examined as the overconsolidation ratio of the retained sand increases. The effect of anchor inclination has also been examined when the wall supports overconsolidated sand. The tests showed that the soil stress history had a very significant effect on the wall and retained sand behaviour.
Breakout of submerged structures buried to a shallow depth
Authors: Byrne Peter M. , Finn W. D. Liam
Published: April 2011

The results from a testing program designed to simulate the problem of lifting an object embedded in the ocean floor are presented and examined herein. The breakout force, defined as the force in excess of the submerged weight required to dislodge the object, was found to depend on the shear strength of the soil or sediment. The maximum breakout force occurs for undrained conditions and can be estimated from bearing capacity equations.The uplift pressure is transferred to the sediments by a reduction in pore-water pressure. If the reduction in pressure is limited by infiltration of water, or any other process, then a reduction in the breakout pressure will result.The reduction in breakout pressure that occurs when time for infiltration is allowed can be estimated from available solution curves from theory of consolidation.
Utilisation du pénétromètre statique dans les Basses Terres du Saint-Laurent
Authors: Maranda Rémy , Dion Denis-Jacques
Published: April 2011

The resistance obtained from static cone penetration tests is compared to the in situ vane shear strength, for the soft to firm clays in the St. Lawrence Lowlands.The average factor Nk, obtained on five sites, varies between values of 2.5–18.4. As a result of this study it is not possible to propose a unique value of Nk to be assigned to Champlain Sea clays. As pointed out by Schmertmann and confirmed in the present analysis, the correlation between field vane and static cone penetration tests must be defined for each site.The soft deposits of the St. Lawrence Lowlands are well suited for studies by means of static cone penetration tests, which are very effective for determining the stratigraphy on the basis of the variations of the point resistance and the friction ratio. [Journal translation]
Dolostone popouts in asphalt, Kingston, Ontario
Authors: VanDine D. F. , Harrison C. M. Truax
Published: April 2011

Standard physical tests for aggregate indicate that most of the carbonate bedrock in the Kingston, Ontario area meets the requirements for asphaltic coarse aggregate. However, when used, some of the aggregate particles have proven to be prone to aggregate loss, also called popping. Studies utilizing the polarizing microscope, the scanning electron microscope, and X-ray diffraction and fluorescence techniques indicate that the aggregate particles which are prone to popping contain a significantly higher proportion of dolomite than calcite, and the crystals are much better formed. The large dolomite crystals result in a poorer aggregate–bitumen bond and contribute to an increased probability of splitting of the aggregate. Both conditions cause aggregate loss from the road surface.
Curve-fitting and laboratory data
Authors: Graham J. , Pinkney R. B. , Lew K. V. , Trainor P. G. S.
Published: April 2011

Evaluation of soil properties from laboratory tests requires the use of empirical procedures. It has proved difficult to establish procedures for identifying yield stresses that are independent of the stress path and the method of plotting. Minicomputers and automatic curve-fitting techniques have been proposed for rational, repeatable, inexpensive results. However, conclusions drawn from the tests still depend strongly on the curve-fitting procedures. Care and judgement are necessary.
A further comparison of shear-wave velocities
Authors: Larkin T. J. , Taylor P. W.
Published: April 2011

In a previous paper by the same authors the values of the shear-wave velocity in natural soils found from laboratory tests were compared with wave velocities measured in situ. Dynamic free-vibration torsion tests were carried out in the laboratory on undisturbed 150 × 75 mm soil samples. Downhole seismic tests were performed at the site to measure the velocity of propagation of low strain shear waves from a surface wave source. Differences between laboratory and field values of the shear-wave velocity were considered to be due to sample disturbance. Further work has established that, provided system compliance in the laboratory apparatus is allowed for, laboratory and field values agree reasonably well. The test results are analysed again with account being taken of the stiffness of the laboratory apparatus.
Stress-deformation predictions for the LG 4 main dam
Authors: Paré J. J. , Verma N. S. , Keira H. M. S. , McConnell A. D.
Published: April 2011

The LG 4 dam, the second largest structure on the La Grande Complex of the James Bay hydroelectric development, is 125 m high, about 4 km long, and is composed of 19 × 106 m3 of fill materials.The design of the dam is characterised by (i) a zoned earth–rockfill section based on a judicious use of the limited quantities of various materials available, (ii) a 70 m high abutment in the river valley with a steep inclination of about 55°, and (iii) a 50 m high section of the dam with its axis curved in the downstream direction.Detailed stress-deformation analyses were carried out in the critical sections of the dam using finite element methods to verify any presence of arching and hydraulic fracturing potentials in the nonplastic till core. An interesting aspect of these analyses was the fact that the material properties were established based on laboratory testing as well as the observed deformation behaviour of the already completed 156 m high LG 2 main dam.The analyses have indicated that the design has adequate reserve of safety against hydraulic fracturing and arching. Nevertheless, the design sections and material placement requirements were optimised, where necessary, to ensure a satisfactory behaviour of the dam. The instrumentation design was also adapted to the findings of this study. Keywords: earth dam, steep abutment, stress-strain, hydraulic fracturing, arching.
Horizontal drains to stabilize clay slopes
Authors: Lau K. C. , Kenney T. C.
Published: April 2011

Five horizontal drains were installed in a natural clay slope and the piezometric heads in the slope were monitored with piezometers. Decreases of piezometric head in the vicinity of the drains were measured and indicated that horizontal drains can be used to improve the stability of clay slopes.Based on the theory of consolidation, estimates were made of the changes of piezometric head within the test slope due to the installation of drains. Good comparisons were obtained between the predicted and the measured values, demonstrating that the method of prediction can be used with confidence for design purposes. The three-dimensional pattern of piezometric levels was averaged to give an equivalent two-dimensional pattern, and this was used in slope stability calculations to determine the improvement in safety factor of the slope.The effectiveness of horizontal drains depends on the spacing and diameter of the drains, and on their location relative to the critical slip zone.The study has shown that installation of horizontal drains is a viable method of improving the stability of certain clay slopes. Keywords: slope, clay, stability, drains, field test, theory.
Comparison of geogrid and geotextile reinforced earth slabs
Authors: Guido Vito A. , Chang Dong K. , Sweeney Michael A.
Published: April 2011

Presented herein is a comparison of the results of laboratory model tests used to study the bearing capacity of geogrid and geotextile reinforced earth slabs. The parameters studied were the coefficient of friction between the geotextile and the soil, pull-out resistance between the geogrid and the soil, depth below the footing of the first layer of reinforcement, vertical spacing of the layers, number of layers, width size of a square sheet of reinforcement, and tensile strength of the reinforcement. For both geogrids and geotextiles, after an optimum number of layers or width of reinforcement, the bearing capacity did not increase. In addition, the bearing capacity was largest for those geogrid and geotextile reinforced earth slabs where the first layer was closest to the footing and the spacing between the layers was the smallest. Bearing capacity increased directly with increasing reinforcement tensile strength for the geotextile; however, for the geogrid, aperture size and reinforcement tensile strength must be looked at simultaneously. Key words: reinforced earth slab, geogrid, geotextile, bearing capacity, pull-out, friction.
In situ creep properties in ice-rich permafrost soil
Authors: Savigny K. W. , Morgenstern N. R.
Published: April 2011

An in situ analysis of naturally occurring creep has been carried out at the proposed Canadian Arctic Gas pipeline crossing of Great Bear River in the Northwest Territories. This is the third of four papers that describe the study. The borehole inclinometer system and monitoring procedures used to determine in situ movement are described. Significant factors affecting the accuracy of the system are assessed. External factors causing movement of the inclinometer casing are also assessed and movements caused by these factors are separated from natural ground movements. The magnitude and nature of naturally occurring creep deformations are discussed.

Key words: Mackenzie Valley, pipelines, slopes, permafrost, soils, geotechnical, inclinometers, creep.
Stability of the north slope and portal at the Edmonton light rail transit crossing of the North Saskatchewan River
Authors: Gerber Gloria E. , Tweedie Robin W. , Bean Stephen M. , Thomson Stan , Eisenstein Zdenek
Published: April 2011

The North Portal for the Edmonton South Light Rail Transit (SLRT) extension is located on the north slope of the North Saskatchewan River Valley west of the High Level Bridge. There was no evidence that the north slope at this location had experienced major, deep-seated slope movements prior to SLRT construction. Since commencement of the North Portal construction, translational slope movements along near-horizontal bentonite layers within the bedrock have developed. Initiation and acceleration of slope movement are believed to be due to the earthwork activities, coupled with precipitation and associated rise in groundwater table. As an interim measure, four deep wells were installed close to the toe of the upper slope in May 1989. The piezometric levels observed after installation of the wells suggest that the drilling of the wells hydraulically connected the various coal–bentonite layers and effectively lowered the higher perched water in the upper coal?bentonite layer. Subsequent slope inclinometer measurements indicate negligible slope movements since the well installations. This paper describes the detailed geotechnical investigations, slope stability assessments, instrumentation, and monitoring records over a 5-year period during and after construction. The paper also describes the implementation of the stabilizing measures and their effects on slope stability. Key words : South Light Rail Transit, North Saskatchewan River Valley, coal–bentonite layers, slope stability, vertical wells.
Behaviour of flexible piles in layered clays under eccentric and inclined loads
Authors: Sastry V.V.R.N. , Meyerhof G.G.
Published: April 2011

The lateral soil pressures, bending moments, pile displacements at the ground surface, and the bearing capacity of instrumented vertical single flexible model piles in a layered clay system consisting of medium clay overlying soft clay under vertical eccentric and central inclined loads have been investigated. The results of these load tests are compared with theoretical estimates based on the concept of the effective embedment depth of equivalent rigid piles for ultimate and elastic cases. Reasonable agreement has been found between the observed and predicted behaviour of flexible piles. The analyses are also compared with the results of some field case records. Key words : bearing capacity, clay, instrumentation, model test, pile.