bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutron-diffraction studies on liquid, glassy, and crystalline Ca0.4K0.6(NO3)1.4
Authors: Kartini E. , Collins M. F. , Collier B. , Mezei F. , Svensson E. C.
Published: April 2011

The temperature dependence of neutron diffraction by Ca0.4K0.6(NO3)1.4, in the liquid and glassy states, was measured together with the time dependence of the transformation to the crystalline states. The measurements were performed over the range of Q from 0.2 to 5.5 Å−1 (1 Å = 10−10 m) for temperatures between 300 and 573 K. On cooling, a glass was formed with a glass transition temperature of Tg = 335 K; on heating, two crystalline phases formed at 375 ± 5 K with melting points of 425 and 444 K. As the temperature increased the height of the main peak in the diffraction pattern decreased, its position shifted to lower Q, and its width increases. Each of these parameters varies linearly with temperature. The metastability of the system was exemplified by the crystallization process, which did not occur on cooling, but which did occur on first cooling to 300 K and then on heating to 375 K. The time dependence of the growth of the crystalline powder peaks shows that there are two characteristic growth patterns, with each observed peak coming from one of two compounds. We also report on studies of quenched and heat-treated Ca0.4K0.6(NO3)1.4 by thermal analysis and X-ray diffraction.
Impulse approximation neutron scattering from N2
Authors: Cowley R. A. , Zinkin M. P. , Eccleston R. S. , Evans A. C. , Harris M. J.
Published: April 2011

We present the results of a detailed investigation of the inelastic neutron scattering from diatomic N2, at wave-vector transfers in the range Q = 20–100 Å−1 (1Å = 10−10 m). At intermediate Q, the scattering shows structure arising from the vibrational modes of the molecule, while at large Q the scattering is well described by the impulse approximation for the individual atoms, despite the fact that the corresponding energy transfers are considerably less than the maximum molecular excitation energies. We find good agreement for all Q with a calculation incorporating the internal rotational and vibrational modes of the molecule explicitly.
The phase diagram of RbFeCl3 in a magnetic field perpendicular to the chain direction
Authors: Dorner B. , Schmid B. , Kakurai K. , Petitgrand D.
Published: April 2011

The temperature dependence of the position and line width of antiferromagnetic Bragg peaks were measured at different applied magnetic fields up to 1.4 T by means of elastic neutron scattering. Three different types of temperature dependences were observed that can be attributed to the commensurate–incommensurate, commensurate–paramagnetic, and incommensurate–paramagnetic phase transitions. Below 0.3 T the transition goes from commensurate to incommensurate. Between 0.3 and 0.5 T a phase boundary was observed, but there is some doubt as to whether the structure at temperatures below this boundary is commensurate. Between 0.5 and 1.2 T the phase transition goes directly from commensurate to paramagnetic at around 2.5 K. For fields higher than 1.3 T and temperatures above 1.5 K no commensurate phase could be identified. But above 1.2 T and still at 1.4 T there exists an incommensurate phase. Based on these temperature dependences at different magnetic fields, phase boundaries in the H–T phase space are proposed and compared with the phase diagram obtained by previous susceptibility measurements.
Giant thermomechanical effect in normal liquid 3He
Authors: Sawkey D L , Deptuck D , Greenwood D , Harrison J P
Published: April 2011

Measurements are presented of the thermomechanical coefficient of normalliquid 3He confined in a porous plug preplated with four monolayersof 4He. These nonmagnetic monolayers displace the magnetic solid-like3He monolayers that are adjacent to the pore surfaces when the plugis filled with pure 3He. In the low-temperature limit (T <= 10mK) the coefficient can be described by Δ P/Δ T ~ s/6vwhere Δ P is the pressure difference across the plug generated bythe temperature difference Δ T, and s and v are the molarentropy and molar volume. This low-temperature limit corresponds to thecondition d <<lq where d is the pore diameter and lq isthe bulk liquid 3He quasiparticle mean free path; that is, thequasiparticles are predominantly boundary scattered in the pores. Themeasured coefficient is half that calculated by Edwards Culman and He. When compared with this new experimental result for the 4He-platedporous plug, the earlier result for pure liquid 3He is strikinglylarger (by up to 30x at 2~mK). This enhancement is reminiscent ofthe giant thermopowers measured in Kondo and other dilute magneticalloys. It is speculated that the enhanced thermomechanical coefficientfor pure liquid 3He is due to magnetic scattering of the 3Hequasiparticles by the two magnetic solid-like 3He monolayers adjacentto the pore surfaces.

PACS Nos.: 67.55.-s and 67.55.Hc
Transition rates in singly ionized titanium
Authors: Luke T M
Published: April 2011

Rates have been calculated for electric dipole transitions in Ti II between the fine structure levels of the terms 4p z 4Go, 4 Fo, 2Fo, 2Do, 4Do, and 2Go to the levels of the groundterm 4s a 4F and comparisons are made with the most recent available observations as well as with the calculations of Kurucz. These are the only other calculations available for this ion. To include certain configurations with more than two open shells, new approximations are necessitated by the complexity of the algebra. The approximations used are described and the results of calculations are given to demonstrate their effectiveness and accuracy. It will be shown that the CPU time reductions are very substantial, sufficient to make the inclusion of potentially important configurations feasible where it would not be so otherwise.The loss in accuracy in the situations examined is negligible. New results for transition rates that have not been measured are presented.PACS Nos.: 32.70.Cs, 32.70.Fw
Asymptotic expansion of the Mathieu and prolate spheroidal eigenvalues for large parameter c
Authors: Do-Nhat T
Published: April 2011

The asymptotic expansions of the Mathieu eigenfunctions and the prolate spheroidal wave functions can be expanded in terms of the parabolic cylinder functions, from which their asymptotic eigenvalue can be expressed in an inverse power series of c, where the parameter c is proportional to the operating wave number. Analytical expressions of the eigenvalues, as well as those of the expansion coefficients of the eigenfunctions, are derived and verified with numerical results.PACS. No.: 2.30 MV
Prediction and mapping of landslide hazard
Authors: Wu Tien H , Abdel-Latif Mohamed A
Published: April 2011

The paper describes a mechanics-based methodology for prediction of landslide hazard on hillside slopes. The principal components are estimation of infiltration and groundwater response, and estimation of safety factor and failure probability. Predictions with the models are made by using the best estimates of the input parameters and the associated uncertainties. The uncertainties about the inputs and the sensitivities of the model outputs to uncertainties about the inputs are evaluated and translated into failure probability. Our objective was to provide a method that can be used to estimate landslide hazard over a large area prior to making detailed site investigations. The method was applied to slopes along the South Fork of Tilton River, in the Cascade Mountains of Washington State. Predicted hazards were compared with results of a landslide inventory. The data used in the examples were derived from published sources. However, the procedures developed are not limited to this condition and can readily incorporate additional information derived from more detailed investigations.Key words: failure probability, groundwater, hazard, landslides, mapping, slope stability.
Tension tests on wedge-piles in sensitive clays
Authors: Hamouche K K , Leroueil S , Roy M
Published: April 2011

The wedge-pile, a piling system in which a pile is expanded once jacked or driven into the ground, was developed at Imperial College, England. The expansion of the pile generates an increase in bearing capacity of the piling system which is closely related to the soil type. In the present study, the wedge-pile system has been tested in three sensitive Champlain clay deposits of different overconsolidation ratios. The piles were tested in tension and the test results show that in such deposits the average increase in pull-out capacity is about 30%, which is relatively small. An approach for predicting the enhancement in pull-out capacity using a closed-end self-boring pressuremeter is proposed. Simulation of the wedge-pile before and after its expansion was performed using this tool and showed that the increase in radial effective stress due to pressuremeter expansion appears to be in good agreement with the increase in the friction mobilized during pile tests.Key words: sensitive clay, wedge-pile, traction test, skin friction, pressuremeter, holding test.
The 1999 R.M. Hardy Lecture: The implementation of unsaturated soil mechanics into geotechnical engineering
Authors: Fredlund Delwyn G
Published: April 2011

The implementation of unsaturated soil mechanics into geotechnical engineering practice requires that there be a paradigm shift from classical soil mechanics methodology. The primary drawback to implementation has been the excessive costs required to experimentally measure unsaturated soil properties. The use of the soil-water characteristic curve has been shown to be the key to the implementation of unsaturated soil mechanics. Numerous techniques have been proposed and studied for the assessment of the soil-water characteristic curves. These techniques range from direct laboratory measurement to indirect estimation from grain-size curves and knowledge-based database systems. The soil-water characteristic curve can then be used for the estimation of unsaturated soil property functions. Theoretically based techniques have been proposed for the estimation of soil property functions such as (i) coefficient of permeability, (ii) water storage modulus, and (iii) shear strength. Gradually these estimations are producing acceptable procedures for geotechnical engineering practices for unsaturated soils. The moisture flux ground surface boundary condition is likewise becoming a part of the solution of most problems involving unsaturated soils. The implementation process for unsaturated soils will still require years of collaboration between researchers and practicing geotechnical engineers.Key words: unsaturated soil mechanics, soil suction, unsaturated soil property functions, negative pore-water pressure, matric suction, soil-water characteristic curve.
The statistics of embankment dam failures and accidents
Authors: Foster Mark , Fell Robin , Spannagle Matt
Published: April 2011

The paper describes the results of a statistical analysis of failures and accidents of embankment dams, specifically concentrating on those incidents involving piping and slope instability. The compilation of dam incidents includes details on the characteristics of the dams, including dam zoning, filters, core soil types, compaction, foundation cutoff, and foundation geology. An assessment of the characteristics of the world population of dams was also carried out. By comparing the characteristics of the dams which have experienced failures and accidents to those of the population of dams, it was possible to assess the relative influence of particular factors on the likelihood of piping and slope instability.Key words: dams, failures, piping, instability database.
Field static load tests on drilled shaft founded on or socketed into rock
Authors: Zhan Caizhao , Yin Jian-Hua
Published: April 2011

The Mass Transit Railway Corporation proposes to construct the Tseung Kwan O Depot (TKD) within Area 86 reclamation at Tseung Kwan O as part of the Tseung Kwan O Extension. The proposed foundation for the TKD comprises about 1000 large-diameter, bored, cast in situ, drilled shafts founded on or socketed into rock. To confirm the design allowable end bearing capacity and rock socket side resistance for the drilled shaft foundations, two test piles were constructed and tested. Both test piles were instrumented with strain gauges and rod extensometers. This paper presents the static compressive load test results on both test piles. The test results indicate that an end bearing capacity of 20.8 MPa (design allowable 7.5 MPa) and rock socket side resistance 2.63 MPa (design allowable 0.75 MPa) are achieved during the pile load tests with no sign of failure.Key words: drilled shaft, static load test, end bearing capacity, rock socket, rock socket side resistance, load transfer.
Evaluation of axial performance of tapered piles from centrifuge tests
Authors: Naggar M Hesham El , Sakr Mohammed
Published: April 2011

The performance of tapered piles under axial compressive loading was investigated using centrifuge model tests. Model tapered and cylindrical piles were installed in cohesionless soil and subjected to axial loading. The objectives of this study were to understand the performance characteristics of tapered piles and develop a rational approach for their design. The results of axial compressive loading tests on 12 one-tenth scale model piles with different taper angles in a centrifuge setup are presented and discussed. Six piles were instrumented and six piles were not. The load distribution along the shaft of instrumented piles was measured and the results were compared with an analytical solution in terms of the taper coefficient Kt. The comparison showed a reasonable agreement between Ktvalues established from the experiments and those obtained from the analytical solution. A simple rational approach was proposed for the design of tapered piles. The proposed approach was used to calculate the bearing capacity of the tested piles, and reasonable agreement with the measured values was obtained. The results of this study suggest that the pile taper should be limited to the top 20-25 pile diameters of the pile length for optimum efficiency.Key words: tapered piles, pile capacity, axial performance, centrifuge modeling, shaft resistance.
Risk-based liquefaction potential evaluation using standard penetration tests
Authors: Juang C Hsein , Chen Caroline J , Jiang Tao , Andrus Ronald D
Published: April 2011

In this paper, a new approach is presented for developing a liquefaction limit state function, which defines a boundary that separates liquefaction from no-liquefaction occurrence. The new approach is developed using a database consisting of 243 field liquefaction performance cases at sites where standard penetration tests (SPT) had been conducted. This database is first used to train and test an artificial neural network for predicting the occurrence of liquefaction or no liquefaction. The successfully trained neural network is then used to establish a liquefaction limit state function. Based on the developed limit state function, mapping functions that relate calculated factors of safety to probability of liquefaction are established. The established mapping functions form a basis for the development of a risk-based chart for liquefaction potential evaluation.Key words: probability, risk-based design, liquefaction potential, SPT, artificial neural network.
Empirical modeling of the compaction curve of cohesive soils
Authors: Basheer I A
Published: April 2011

Compaction curves (or densitymoisture relationships) of cohesive soils are essential components for establishing practical and reliable criteria for effective control of field compaction. In this paper, modules built from empirical models for simulating the compaction curves of cohesive soils based on easily measured basic soil properties and compaction energy were developed using both statistical regression and artificial neural networks (ANNs) techniques. A large number of compaction curves pertaining to a wide variety of fine-grained soils were collected and used in modeling. The developed modules were able to predict compaction curves of soils with good accuracy, with the ANN-based module outperforming the statistical-based analog. The compaction modules were utilized to inquire about the compactibility behavior of fine-grained soils in relation to their properties and the compaction energy used. Besides their use as independent compaction curve predictors, the compaction modules can be used as supplementary units in numerical models for solving geotechnical engineering problems and as tools useful in preliminary design phases and feasibility studies.Key words: cohesive soils, compaction curve, modeling, neural networks, regression.
A possible physical meaning of Case damping in pile dynamics
Authors: Zhang Limin , McVay Michael C , Ng Charles WW
Published: April 2011

This paper presents some possible interpretations of the physical meaning of the lumped, toe, and skin Case damping factors, jcL, jct, and jcs, respectively, which are extensively utilized in the dynamic analysis of pile driveability and capacity. A single degree of freedom model is employed to relate the Case damping to the hysteretic damping ratios of soil and pile materials. This relation and the damping ratios of soils and piles show that the Case damping factors for piles in sandy and clayey soils may overlap at all strain magnitudes. Coupling of pile toe and skin resistance is analyzed, and the jcLfactor is found to be a function of the skin and toe resistance ratio of the pile. Consequently, the jcLfactor is an important indicator with which the skin friction and toe resistance of piles can be separated. A database of 133 cases of dynamic pile tests in Florida has been used to substantiate the analyses and interpretations. The effects of the assumptions made in this paper are also discussed.Key words: pile dynamics, wave equation, Case damping, hysteretic damping, bearing capacity, skin friction.
Characterization of the disturbed zone in a large rock excavation for the Three Gorges Project
Authors: Deng J H , Lee C F , Ge X R
Published: April 2011

Excavation in a rock mass leads to the perturbation of the stress regime, often creating a stress-relieved, locally weakened zone known as the disturbed zone. This paper presents the results of in situ studies that were carried out both in the central rock barrier (or separation block) between the shiplift and the temporary shiplock and in the northern slope of the permanent shiplock of the Three Gorges Project. The vertical extent of the disturbed zone was determined jointly by cross-hole seismic wave penetration testing and borehole elastic modulus testing, and the horizontal extent was assessed by monitoring and evaluating the deformation characteristics. Compared with the undisturbed rock mass, the P-wave velocity of the disturbed zone was reduced by 3438% and the borehole elastic modulus by 1231%. The reductions were caused by the opening of primary structural planes or the extension of apertures due to local sliding along the structural planes. In the disturbed zone, no newly formed fractured planes were found. The observed disturbed zone was compared with the tensile stress zones and the shear-damaged zones calculated by the finite element method. A rock reinforcement scheme was recommended and implemented.Key words: disturbed zone, mechanical properties, brittle rock mass, excavation, finite element method, reinforcement.
Characterization of Singapore, Bangkok, and Ariake clays
Authors: Tanaka Hiroyuki , Locat Jacques , Shibuya Satoru , Soon Tan Thiam , Shiwakoti Dinesh R
Published: April 2011

A soil investigation was carried out at two sites in Singapore and Bangkok, Southeast Asia, and the results were compared with those from a site in Ariake, Japan. Soil samples at all the sites were retrieved using the Japanese sampling method to nullify the effect of sampling on sample quality. From the laboratory tests, consolidation characteristics and undrained shear strength were measured. In addition to the mechanical tests, X-ray diffraction and scanning electron microscope tests were carried out to identify clay minerals and to study their microstructure. Great differences in physical and mechanical properties of these clays were observed, which may be attributed to the difference in their clay mineral components and variation in the sedimentation environment.Key words: site investigation, marine clay, undrained shear strength, anisotropy, consolidation, clay mineral.
Static liquefaction as a possible explanation for the Merriespruit tailings dam failure
Authors: Fourie A B , Blight G E , Papageorgiou G
Published: April 2011

In 1994 the Merriespruit gold tailings dam in South Africa failed, resulting in 17 deaths. The post-failure investigation provided no explanation as to why the catastrophic flow failure, which contradicted all previous experiences of failures of gold tailings dams in South Africa, occurred. The documented history of the dam describes insufficient freeboard provision and often poor pool control, which is argued to have resulted in some areas of the dam having high in situ void ratios. Some of the undrained triaxial tests carried out on specimens obtained from zones adjacent to the failure scar exhibited nondilative behaviour. Laboratory triaxial tests that were conducted on reconstituted specimens and are reported in a companion paper defined a series of steady state lines that were dependent on the particle-size distribution of the tailings. Void ratios obtained from undisturbed samples taken during the post-failure investigation are compared with these steady state lines and it is shown that an appreciable percentage of the specimens were likely to have been contractant. The inference drawn is that a large volume of tailings was in a metastable state in situ and overtopping and erosion of the impoundment wall exposed this material, resulting in static liquefaction of the tailings and a consequent flow failure.Key words: static liquefaction, gold tailings, Merriespruit, failure.
Confining stress and static shear effects in cyclic liquefaction
Authors: Vaid Y P , Stedman J D , Sivathayalan S
Published: April 2011

Liquefaction resistance of a sand under cyclic loading is assessed and the effects of the levels of confining pressure and static shear on resistance to liquefaction are investigated. Site-specific values of the resistance under specified levels of confining and static shear stresses are measured in the laboratory. The measured values are compared with those which would be predicted by the application of empirical multiplying factors Kσand Kαto the reference resistance at 100 kPa effective confining stress with no static shear. It is shown that Kσand Kαare not independent, as assumed in current practice. The combined factor Kσ× Kαresulting from the empirical method is shown to underestimate the cyclic resistance ratio regardless of the initial density and confining and static shear levels. The degree of conservatism is most dramatic at looser density states.Key words: sand, liquefaction, static, cyclic, static shear, confining stress.
Landslides in weakly cemented glaciolacustrine sediments, Morkill River valley, British Columbia
Authors: Froese Corey R , Cruden David M
Published: April 2011

Slopes in weakly cemented glaciolacustrine sediments in the Morkill River valley in the Canadian Rocky Mountains stand at up to 70°. Based on field and laboratory observations it appears that a contributing factor to instability is the softening of the soils by frost action and the leaching of calcite cement. Field density profiles demonstrated increased density and carbonate content with an increase in depth. Laboratory tests of carbonate content indicated a positive correlation between calcium carbonate and density in the glaciolacustrine sediments. The relationship was strongest in sands, in which leaching and dissolution were important components of softening. In clays, frost action was the dominant component of softening. Freeze-thaw tests showed a 50% decrease in strength after one cycle of freeze and thaw in the silts and clays.Key words: landslide, cemented, glaciolacustrine sediments, British Columbia.
A new procedure for computing the factor of safety using the Morgenstern-Price method
Authors: Zhu D Y , Lee C F , Qian Q H , Zou Z S , Sun F
Published: April 2011

By employing the same assumption regarding interslice forces as that used in the Morgenstern-Price method, two concise recurrence relations between interslice forces and interslice moments are derived which satisfy both force and moment equilibrium conditions. The Newton-Raphson method is used for determining the factor of safety and the associated scaling parameter of the interslice force function. Algebraic derivatives required in the solution process are evolved in a recursive manner which can be easily implemented in a computer program. The choices of initial values of safety factor and scaling parameter are suggested. The procedure proposed in this paper proves to be efficient and solutions converge rapidly.Key words: slope, stability, factor of safety, limit equilibrium method.
Fracture toughness of frozen base and subbase soils in pavement
Authors: Konrad Jean-Marie , Cummings Julie
Published: April 2011

Temperature distribution in the pavement structure, moisture distribution in granular soils, modulus of the asphalt concrete, and fracture toughness of material in the pavement structure strongly influence the propagation and spacing of thermal contraction cracks. Fracture toughness was determined for frozen sand (subbase layer) and frozen crushed stone (base layer) by adapting established fracture mechanics test procedures recommended in American Society for Testing and Materials standard test method E399-83 for metals. It was established that fracture toughness increases with decreasing temperature and increasing volumetric ice content. For a temperature of 5°C, the fracture toughness of frozen crushed stone increased almost linearly from 0.05 to 0.40 MPa·m0.5 when the volumetric ice content increased from 6 to 14%. For frozen sand, the fracture toughness KIC in a wedge-opening mode increased from 0.04 to 0.70 MPa·m0.5 when the volumetric ice content increased from 8 to 28%. It was also established that the fracture toughness of frozen soil decreases with decreasing soil average grain size according to a logarithmic law.Key words: fracture, toughness, experimental, frozen, granular soil, pavement.
A user's approach to assess numerical codes for saturated and unsaturated seepage conditions
Authors: Chapuis Robert P , Chenaf Djaouida , Bussière Bruno , Aubertin Michel , Crespo Rodolfo
Published: April 2011

Numerical models are useful tools to evaluate problems and design remedial measures relative to groundwater seepage. They provide information for decision-making and guidance for collecting new data. Most users do not know in detail how the numerical code works. However, they must be sure that it gives reliable predictions for the problem under study. The major questions relative to the computer calculations are as follows: Can the results of the code be trusted? Under which conditions and to what extent are its predictions uncertain? This paper describes an approach that can be followed by model users to evaluate the results of a groundwater numerical code. This approach is relatively general, although each code is unique and may require specific controls. It begins with simple problems and progressively moves towards more complex problems: from steady-state to unsteady-state conditions, from one- to three-dimensional problems, and from saturated to saturatedunsaturated conditions. This approach is illustrated with a commercial code that passed the successive tests.Key words: groundwater, numerical code, quality control, saturated and unsaturated seepage.
Failure of an Embankment Founded on Varved Clay
Authors: Lo K Y , Stermac A G
Published: April 2011

During the construction of a 19 ft. high roadway embankment at New Liskeard, Northern Ontario, on varved clay, a failure involving half the width of the embankment occurred, extending for a length of 350 ft. A comprehensive investigation was carried out, including continuous sampling and in situ vane tests at 2 ft. intervals to locate the failure zone.Stability analyses were carried out both for the failed and the stable side of the embankment, assuming different values of fill strength and depth of tension cracks.Prior to construction, 30 piezometers and 14 settlement gauges were installed at a section close to the failure region. Extrapolation of the pore-pressures measured at this location to the failure section enabled the stability study to be performed in terms of effective stresses. Analyses were also carried out for the instrumented section both in terms of total and effective stresses.The results of this study show that: (a) The discrepancy between in situ vane and laboratory tests carried out in the varved clay stratum is of the same order of magnitude as those experienced in homogeneous deposits. (b) The [Formula: see text] analysis gives approximately correct factors of safety in all the cases analysed when both fill strength and effect of tension cracks are taken into account. (c) The factors of safety given by effective stress analysis appear to be too high.The remedial measures subsequently carried out for the failure region are described.
A Till Cofferdam in the St. Lawrence River
Authors: Sutcliffe F H
Published: April 2011

This paper deals with the design, construction, and performance of a drydock in the St. Lawrence River enclosed by a till dyke dumped in water. Alternative designs and methods of selecting a suitable till are discussed. Construction procedures are described along with the installation of a two-stage wellpoint system to intercept seepage through the riverbed beneath the dyke. Particular emphasis is placed upon the methods of control and observations taken both during and after construction.It is concluded that a till dyke dumped in water can form as table and impermeable mass; however, care must be taken to apply any surcharge slowly to allow time for the dissipation of pore pressures in the underwater till.
The Variability of Natural Soils
Authors: Lumb Peter
Published: April 2011

The variations in properties of four typical natural soils are shown to be random variations about a mean or linear trend, related to the “normal” or “Gaussian” statistical distribution. Examples are given of soil properties following the normal, log-normal, and bi-normal distributions. Properties studied include Atterberg limits, grading, and, for undisturbed samples, strength and compressibility characteristics.A rational basis for the choice of a design parameter, such as strength or compressibility, is the probability that the parameter could be less than the design value. For any particular probability the design parameter can be determined using the normal distribution.In the case of bearing capacity estimates, an analysis of the conventional factor of safety suggests that a suitable value of probability or “risk” of failure for design is of the order of 10−2 to 10−3 per cent.In the case of settlement estimates, upper and lower bounds to the magnitude and rate of settlement can be associated with a particular probability or risk.
Landslide on the Toulnustouc River, Quebec
Authors: Conlon Robert J
Published: April 2011

A landslide in a very stiff beat extra-sensitive (or quick) deposit of fine-grained estuarine sediments involved approximately five million cubic yards of soil. The overall instability is attributed to a mechanism of progressive failure. It is reasoned that the propagation of a failure surface and the development of a failure scarp all occurred while the landslide mass remained intact. The whole mass then moved down and out, completely blocking the Toulnustouc River within a few minutes.The particularly high strength of the Toulnustouc estuarine sediments, with natural undrained shear strength values of the order of 8000 lb./sq.ft., together with a remoulded consistency of a viscous liquid, offered a somewhat unique opportunity to study the mechanical behaviour of the structure of a sensitive soil. On the basis of the test results, the concept of an “open, cementation-bonded structure” is developed. This concept is used not only to understand the behaviour of the laboratory samples, but also to understand the mechanism of the landslide. It is believed that this conceit of soil structure may be applicable to all sensitive Canadian marine and estuarine clays.
The Measurement of Pore Water Pressures Adjacent to a Driven Pile
Authors: Hanna T H
Published: April 2011

Two experiences with the use of a new piezometer are reported. The principle of operation is similar to the Geonor piezometer in that water permeates through a porous membrane. The main difference lies in the method of construction and installation. This instrument was designed for measuring the water pressures adjacent to a driven steel pile. To achieve this, the piezometer is welded to the outside face of the pile and driven with the pile. The installation technique was satisfactory and the instrument is considered successful. A number of different applications and modifications are proposed and these are enumerated briefly. Finally the sensitivity of the instrument is considered in the Appendix.
Settlement of a Furnace Foundation, Sorel, Quebec
Authors: Golder H Q , Osler J C
Published: April 2011

The Smelter of Quebec Iron and Titanium Corporation at St. Joseph de Sorel, Quebec, is located in an area which is underlain by about 80 feet of compact stratified sand, silt, and clay, followed by at least 150 feet of Leda clay. Five furnaces were constructed during 1950–52, and four more furnaces have been added subsequently. Settlement records spanning some fifteen years are available for the original furnaces.Recently, it was decided to replace No. 1 Furnace with a new unit, the weight of which will be slightly more than twice that of the existing furnace. The present furnace is founded on 32 Franki piles of 75 tons capacity; the piles are 22 feet long and are cut off about 5 feet below ground level. As it was desired to incorporate the existing piles in the foundation for the new furnace it was necessary to know whether new piles could be driven and loaded together with the existing piles without causing overstressing of the latter, which had been preloaded by the weight of the existing furnace.A settlement analysis of the existing furnace foundation was undertaken, in which sensible agreement was obtained with the observed settlements. Predictions of the rebound of the existing furnace foundation during demolition were made and these were in approximate agreement with field observations. Finally, an estimate of the settlement which the new furnace will experience was made.A significant feature of the problem is that a large portion of the total settlement experienced to date is due to consolidation of the underlying Leda clay stratum, despite the fact that the furnace foundation areas are small in size compared to the thickness of the overlying granular deposits, thereby inducing only small increases in pressure in relation to the existing overburden pressure.
Performance Monitoring of a Deep Cofferdam in Sensitive Clay
Authors: Pappas N D , Sexsmith D P
Published: April 2011

A deep, steel sheet piled, figure-eight cofferdam with circular steel wales was installed as a temporary substructure during the construction of the City of Ottawa Pollution Control Centre Project. A program of strain monitoring was developed and carried out and the results, including inferred soil pressures, are presented.
THE PORE PRESSURE – STRAIN RELATIONSHIP OF NORMALLY CONSOLIDATED UNDISTURBED CLAYS: PART I. THEORETICAL CONSIDERATIONS
Authors: Lo K. Y.
Published: April 2011

This paper presents a critical review of the current theories of predicting pore pressures in saturated clays. These theories are generalized and examined and their limitations discussed. It is shown mathematically that the pore pressure induced by shear may be expressed as a sole function of major principal strain, and this approach eliminates the anomalies inherent in the "stress theories" for pore pressure. A hypothesis is also developed to provide a possible mechanism of pore pressure set up in undisturbed normally-consolidated clays.
THE PORE PRESSURE – STRAIN RELATIONSHIP OF NORMALLY CONSOLIDATED UNDISTURBED CLAYS: PART II. EXPERIMENTAL INVESTIGATION AND PRACTICAL APPLICATIONS
Authors: Lo K. Y.
Published: April 2011

Experimental results on normally-consolidated undisturbed clays of various sensitivities are presented and analyzed using the approach developed in Part I. It is shown that, both for isotropically and anisotropically consolidated samples, the pore pressure ratio – strain relationship is independent of the magnitude of consolidation pressures, time of sustained stress, time of consolidation and intrinsic anisotropy under both plane strain and axially-symmetric stress conditions. The effect of the intermediate principal stress may be taken easily into account so that the pore pressure set up under plane strain condition may be estimated from results of laboratory triaxial tests. The effect of strain rate was found to be small for the clays tested, and becomes insignificant at large strains.The relevance of each of these conclusions in relation to practical problems are discussed. The use of the pore pressure – strain approach in practice in general, and for some class of field problems in which the approach is especially suited, are pointed out.
Outardes 4 — Barrage principal
Authors: Dussault R. , Larocque G. S. , Ouimet J. M.
Published: April 2011

The following article deals with the design and construction of the main dam at the Outardes 4 development. The structure is an earth and rockfill dam reaching a maximum height of 400 ft (~121.9 m). The characteristics of the site, the choice of the type of structure, the principal properties of the materials, the typical cross-section, and stability analysis are either mentioned or described. The construction and control methods are discussed and a brief description of the instrumentation in the dam is also given.
Safety factors and the probability distribution of soil strength
Authors: Lumb Peter
Published: April 2011

For soils exhibiting both cohesive and frictional components of strength, the natural variabilities of the components are compared for soil in the undisturbed state and as compacted in earth dams. The probability distributions of the components are shown to agree more closely with a theoretical beta distribution than with the commonly assumed normal distribution.The cohesive and frictional components can be regarded as independent variables and the design safety factor interpreted in terms of probabilities. Assuming equal probabilities for each component leads to the use of partial safety factors which are larger for the cohesive part than for the frictional part. For long-term stability problems limiting partial safety factors corresponding to zero probability can be obtained.The undrained strength of clays also agrees with a beta distribution but in this case there are no limiting safety factors, and some non-zero probability must be associated with the design.
Investigation of heave in Billings shale by mineralogical and iogeochemical methods
Authors: Penner E. , Gillott J. E. , Eden W. J.
Published: April 2011

A building founded on Billings Shale has suffered nearly 4 in. (10 cm) of heave to its basement floor slab. The heaved zone was thought to be associated with a fault zone in the shale, ear which the rock was fractured and contained extensive pyrite intrusions. Investigations have shown the heave to be due to the weathering of the pyrite in the presence of autotrophic bacteria. Factors creating a favorable environment for this complex weathering process are discussed.
Coupled Rocking and Lateral Vibrations of Embedded Footings
Authors: Urlich C. M. , Kuhlemeyer R. L.
Published: April 2011

A numerical model is described that was utilized to solve the problem of steady state coupled rocking and lateral vibrations of footings embedded into an elastic half space. The good accuracy of the model is confirmed by comparing results obtained for footings founded on the surface of the half space with corresponding results obtained by Veletsos and Wei (J. Soil Mech. Found. Div. Am. Soc. Civ. Eng. 97, pp. 1227–1249, 1971). The results indicate that embedded footings behave dynamically in a manner that cannot be properly predicted by the use of an appropriate embedded footing static spring constant in conjunction with displacement functions obtained for surface footings.
Prediction of Foundation Deformations in Edmonton Using an In Situ Pressure Probe
Authors: Eisenstein Z. , Morrison N. A.
Published: April 2011

For overconsolidated soils and soft rocks the instantaneous component of foundation settlement or heave is a substantial part of the total deformation. Hence, for such cases large portions of the total deformation can be estimated using the theory of elasticity if representative moduli can be determined. However, deformation moduli, especially in overconsolidated soils, are susceptible to sample disturbance and this severely restricts the accuracy of predicting foundation deformation based on laboratory test results. In Edmonton, settlements of large buildings are overestimated 10–30 times if oedometer results are used. Therefore an in situ pressure probe technique has been used to measure moduli of instantaneous deformation in boreholes penetrating foundation strata near two multi-storey buildings in Edmonton — the C.N. and A.G.T. Towers. For these structures records of either settlements (C.N. Tower) or excavation heave (A.G.T. Tower) were available. The moduli obtained from in situ pressuremeter tests were used in the finite element analysis. The results agree remarkably well with field observations and demonstrate the applicability of this method in practice. The economics of the pressure probe investigation technique is competitive with existing methods.
Settlement Performance of Two Embankments on Deep Compressible Soils
Authors: Samson Laval , Garneau Raymond
Published: April 2011

The Autoroute de la Rive Nord on the north shore of the St. Lawrence River traverses deep deposits of compressible soils in the Berthierville area. Where the four-lane autoroute spans a railroad spur line and Highway 41, the upper 60 ft (18 m) of subsoil consists of layers of silty sand, silty clay, sand and silt, stratified silty clay and sand, and overlies 182 ft (55 m) of marine clay. The distance between the railway and Highway 41 is 400 ft (120 m), and the overpasses are connected by a granular fill. This fill has a total height of 35 ft (10.7 m), and, for stability reasons, required stage construction and stabilizing berms. A 25 ft (7.6 m) temporary preloading fill was also placed on Highway 41 to increase the shear strength of an underlying upper clay layer as required for steep slope design at the overpass abutments.Laboratory testing indicated that the upper 60 ft (18 m) of the foundation soils are normally consolidated fluvial deposits and that large settlements of the embankments were to be expected. The lower marine clay is overconsolidated by 0.8 ton/ft2 (0.8 kg/cm2).Periodic observations taken since the beginning of construction in 1964 show that the autoroute embankment has settled 7.4 ft (2.26 m) and that settlement is continuing at a gradually decreasing rate. Deep settlement gauges and piezometers show that most of the settlements are due to the consolidation of the upper 60 ft (18 m) of soil. The lower marine clay is consolidating at a much lower rate and will cause settlements for many years.Analysis of field observations demonstrates that the measured settlements are attributed to the primary consolidation of the compressible strata resulting from the dissipation of pore pressure. In general, the measured settlements compare favorably with the predictions based on laboratory tests. Field and laboratory soil properties are also compared.This paper presents a detailed record of the laboratory investigation and field observations made in conjunction with the construction of the permanent autoroute embankment and the temporary preloading fill. Extensive field studies on negative skin friction on piles have been conducted at the same site, and the results have been reported elsewhere.
An Experience with Heave of Cast In Situ Expanded Base Piles
Authors: Brzezinski L. S. , Shector L. , Macphie H. L. , Noot H. J. Vander
Published: April 2011

On a project just west of the City of Montreal pile heave was experienced during the installation of groups of cast in situ cased expanded base concrete piles, driven through about 30 ft (9 m) of sensitive marine clay to end bearing in a glacial till formation. The paper describes the observed heave occurrence and discusses factors affecting pile and soil heave. Of special interest is the behavior of the piles during retapping since a number had final refusal elevations which were both high and low with respect to initially installed elevations. Possible explanations for this behavior and considerations pertinent to installation procedure, site inspection, load testing, and specifications for this type of pile are discussed within the paper.
Pore Pressures and Strains After Repeated Loading of Saturated Clay
Authors: Wilson Nyal E. , Greenwood John R.
Published: April 2011

Repeated and sustained loading tests on undrained samples of normally consolidated lacustrine clay are used to prove the existence of a relationship between pore water pressures and axial strains.The behavior of the clay is studied by investigating the pore pressure and strain responses under repeated loading, and comparing them with the responses from the more usual sustained loading. Samples under repeated loading fail at a stress below the compressive strength of the material as obtained from a standard strength test.It has been shown that, for a repeated stress level below a critical value a nonfailure equilibrium state is reached, closed stress–strain hysteresis loops occur and the soil behavior is essentially elastic. For a repeated stress above the critical value, the effective stress failure envelope is reached and each loading cycle leads to further nonrecoverable deformations and ultimate failure.The pore pressures and axial strains produced by loading may be divided into recoverable and nonrecoverable components; both components of pore water pressure are linearly related to the axial strain provided the sample is not close to failure and there is a gradual increase in axial strains and pore pressures with time. This relationship is explained by a simple mechanistic picture.The pore pressures due to the application of a shear stress may be considered as a combination of an elastic recoverable component, due to the elastic response of the soil grain structure, and a plastic nonrecoverable component due to a partial collapse of the grain structure with subsequent transfer of stresses from the failed grain contacts to the pore water. There are coresponding axial strains occurring due to the elastic response of the soil grain structure and the partial collapse of the structure.Experimental proof of the pore pressure versus strain relationship is presented by means of a series of loading tests on normally consolidated lacustrine silty clay samples tested under undrained triaxial conditions.
A Device for the Constant Rate of Penetration Test for Piles
Authors: Garneau Raymond , Samson Laval
Published: April 2011

An apparatus was set up for load testing piles at constant rate of penetration (C.R.P. test). The testing equipment consists of a hydraulic jack fed by a high pressure electrical pump equipped with a flow regulator. Examples of pile test results are given.
Particularités rencontrées dans la région de Montréal résultant de l'arrachement d'écailles de roc par la glaciation
Authors: Durand Marc , Ballivy Gérard
Published: April 2011

Several cases of abrupt changes in the bedrock topography were encountered during the excavation of the Metro extension; they are described briefly and their importance on design from preliminary surveys is discussed. The authors comment on their origin which is related to the low dip of the bedding, the presence of a weak layer at depth, and to the horizontal force exerted by glaciers.