bluuebunny/crossref_metadata_2025 huggingface dataset:
A linear log d  log w model for the determination of consistency limits of soils
Authors: Feng Tao-Wei
Published: April 2011

A linear logarithmlogarithm model for the fall cone penetration depth versus water content relationship (flow curve) has been developed based on the results of an experimental study using the British fall cone apparatus. The fall cone flow curve is expressed by a simple equation with parameters m and c, which represent the slope of the flow curve and the water content at a penetration depth of 1 mm, respectively. For a soil, the flow curve can be determined by applying a linear regression analysis to at least four data points with penetration depths approximately evenly distributed between 25 and 3 mm. It is shown in this paper that both the liquid limit and the plastic limit determined from the linear logarithmlogarithm flow curve are in close agreement with those determined from conventional methods. A one-point method for determination of the liquid limit is developed from the model and is verified by applying statistical analysis to a large volume of experimental data.Key words: fall cone, laboratory tests, consistency limits, clays.
Soil Mechanics aspects of the Red River Floodway
Authors: Mishtak J
Published: April 2011

The Floodway will be a 30-mile-long diversion channel in Lake Agassiz lacustrine clays, designed to protect the Greater Winnipeg Area against future flooding. The main soil engineering design problem was the selection of slopes for the diversion channel which would have long-term stability. The paper describes two general methods of investigation: (a) a study of the inclination of natural river banks in the Winnipeg area, and (b) field stability studies of slopes in a freshly excavated trench instrumented with alignment hubs, slope indicators, and piezometers. Some laboratory soil test results are also given. The studies indicate that a design slope of 6 horizontal to 1 vertical for most of the Floodway should be stable.
An Experimental Study of the Load Distribution in Pile Groups in Sand
Authors: Beredugo Y O
Published: April 2011

A series of model tests was carried out to determine the distribution of load among piles grouped in sand. The effects of initial sand density, pile roughness, driving order, spacing, and the position of the pile in the group on the load distribution were studied. The results showed that, for small loads, the load distribution was random. As the load increased, the distribution was governed mainly by the driving order, but as the ultimate group load was approached the effect of driving order diminished and the position of the pile in the group became the predominant factor on which the load distribution depended.In general the centre (or centre core) piles of a group carried the greatest proportion of the load at the ultimate group load while the corner piles carried the least proportion. Beyond the ultimate group load, there was a redistribution of the load in such a way that all piles carried an approximately equal share of the load irrespective of their driving order and position. As the spacing was increased, the distribution tended to become independent of both driving order and pile position, and all piles carried an approximately equal share of the load. Initial soil density, pile roughness, and group size were found to affect the total group loads, but had no effect on the load distribution.
The Performance of a Timber Crib Founded on Soft Very Sensitive Lacustrine Clay
Authors: Brzezinski L. S
Published: April 2011

As part of the development of a site in northern Quebec for a paper mill and associated townsite, a separate water intake structure and pumping works were required to serve the townsite. A timber crib intake structure was constructed approximately 200 ft. offshore in a lake, founded on very soft to soft clay, of high moisture content and sensitivity.The clay is a late glacial freshwater sediment which has been consolidated by pressures probably not exceeding the existing overburden pressure. Careful sampling and testing of the clay, however, indicated a two-part consolidation curve, with the break occurring at a point about 400 lb./sq. ft. in excess of the in situ overburden pressure. Beyond the break in the oedometer curve the compression index was up to 30 times greater than in the initial portion, being a maximum of 3.0 to 3.5.The crib was founded on a sand and gravel mattress, keyed into the lake bottom, the resulting net stress increase on the clay being slightly within the inferred range of apparent preconsolidation established by laboratory tests. Performance readings on the crib for a period of about a year after construction have substantiated the field existence of an apparent preconsolidation of about the order of magnitude predicted by laboratory tests.
Settlement Observations at Kars Bridge
Authors: Eden W J , Poorooshasb H B
Published: April 2011

A 26 ft. high approach fill was constructed in November 1959 for a bridge over the Rideau river near Kars, Ontario. The fill was placed over 50 ft. of Leda clay, the lower 30 ft. of which was extremely sensitive and compressible. Prior testing indicated that the preconsolidation pressure of the clay would be exceeded.Settlement gauges and piezometers under the fill have been observed since the start of construction. After 7½ years, 20 in. of settlement has occurred under the centre of the fill. Settlements are continuing at an appreciable rate although the excess pore water pressure has dissipated to a low level and is nearly constant through the clay layer.The field observations of settlement and pore water pressure are compared with values calculated and a closed form solution to the process of consolidation obtained by a heat balance integral technique and by considering the clay layer to be a rigid plastic.
FOUNDATION ANCHOR PILES IN CLAY-SHALES
Authors: Jaspar J. L. , Shtenko V. W.
Published: April 2011

Earth dams and appurtenant structures in the Prairie Provinces are often constructed on a clay-shale foundation. Concrete structures such as spillways may be damaged due to swelling of the foundation or to differential movements. Various protective devices have been installed to reduce and control the amount of swelling and differential heave beneath structures. Hold down piles have been used, which were mainly reinforced concrete with the bottom flared out. This type, which could take little strain, often became ineffective either through breakage or slippage. To overcome this problem, anchor piles were designed to stretch a certain extent without failure due to load applied through swelling of the shale. It was not intended that this type of pile would eliminate swelling, but that it would reduce the rate and amount of swelling or differential movement. The design includes recommendations regarding depth of anchoring, pile spacing, and size of anchor rod for various bell sizes.
Étude des sables submergés par échantillonnage non remanié
Authors: Tavenas F. , Capelle J. F. , Rochelle P. La
Published: April 2011

The aim of this paper is to present a method of investigation of submerged sand deposits based on undisturbed sampling by an ancient but not widely used technique. After a rapid description of the equipment and technique, three case histories where this method was used are considered. These lead to some important remarks concerning the quality of the samples, the limits of applicability of the method, and finally the validity of the well-known relationships between standard penetration index and relative density, friction angle, or modulus of elasticity of sands.
The Uplift Capacity of Foundations Under Oblique Loads
Authors: Meyerhof G. G.
Published: April 2011

The previous theory of vertical uplift capacity of foundations has been extended to foundations under oblique loads. The analysis is compared with the results of model and some field tests on rigid anchors and piles in sand and clay. The influence of load inclination on the uplift resistance can be represented by an interaction relationship between the vertical and horizontal components of the ultimate load.
Temporary and Permanent Earth Anchors: Three Monitored Installations
Authors: Trow William A.
Published: April 2011

This paper presents the results of measurements of earth anchor performance for three separate installations in Metropolitan Toronto. The first case records the results of instrumentation on the high grout pressure Bauer anchor used to support an approximately 30 ft (9.1 m) deep excavation in dense fine sand. The second presents the load measurements made on low grout pressure earth anchors installed in very stiff clay of a 29 ft (8.8 m) excavation. The third installation involved measurements on permanent vertical anchors set in extremely dense silt till.In the first instance the average measured load was somewhat lower than the installed load and the design assumption. In the second case, in the stiff clay, the load was somewhat higher than the design value but this was attributed to the probability of load transfer because of inadequate support at lower levels. In this case, considerable variation and possible overstressing of anchor wires was noted.A very high uplift resistance was recorded for the permanent anchors in dense till. Control of groundwater during installation of these anchors was the principal lesson learned from this work.
Accurate Measurement of Displacement
Authors: Wilson Gilbert
Published: April 2011

The effects of lateral displacements on building structures is presently receiving considerable attention.A method is described whereby very accurate measurements of lateral displacement can be made economically.The tensioning device of the Potts Mark II Bore Hole Extensometer is graduated to 0.001 in. (0.0025 cm). Some relatively inexpensive hardware has permitted this instrument to be adapted to measuring horizontal displacements using steel tape (or invar tape where temperature changes occur). Reference points can be mounted on the columns of existing buildings or in bore holes (if movements of the ground surface are required).Reference points may be spaced anywhere from a few feet apart to over 100 ft (30 m).Measurements can be taken by one person and, over distances of 20 ft (6 m), displacements can be measured to an accuracy of ±0.0005 in. (0.001 cm) under ideal conditions.
Study of Bridge Foundation Performance Under Dynamic Loading
Authors: Dodds Robert B. , Ganapathy G. V.
Published: April 2011

Seismographic equipment was used to study the response of a railway bridge under dynamic train loading and thereby to determine the performance of the foundations of the bridge. The same methods were used to determine the effectiveness of remedial work done on the bridge piers and on the subsoil beneath the piers.The bridge was constructed in 1898 and is a three-span, masonry and stone arch bridge, 273 ft (83.2 m) in length. The east abutment is founded on bedrock, however, the west abutment and two piers in the river bed are founded on deep alluvial deposits.Seismographic studies indicated relatively large movements of one pier which were attributed to foundation scouring. A program of grouting the pier subgrade confirmed this assessment. Subsequent seismographic studies confirmed the effectiveness of the remedial works undertaken. The studies of the bridge responses under dynamic train loading provided sufficient data that scour areas beneath a pier could be pinpointed.The technique applied on this project determined bridge pier foundation conditions much more quickly and economically than a normal program of exploratory drill holes. The same technique could be used to assess the behavior of individual components of a bridge structure.
Behavior of an embankment on New York varved clay
Authors: Leathers Francis D. , Ladd Charles C.
Published: April 2011

The foundation soils for an embankment in New York State constructed on preconsolidated varved clay were instrumented to determine pore pressures and settlements during and after construction. Four embankment cross sections, three of which had sand drains, are analyzed in this paper. Predictions of the in situ undrained pore pressures, initial settlements and final consolidation settlements are presented and compared with the results of field measurements. Undrained pore pressures and initial settlements are predicted using the finite element program FEECON for plane strain embankment conditions and elastic theory for three-dimensional embankment conditions. Final consolidation settlements are predicted using a modification of the Skempton–Bjerrum approach. At cross sections with sand drains, predicted undrained pore pressures are adjusted to account for the effect of the sand drains. In addition, vertical and horizontal coefficients of consolidation are determined from the field measurements and compared with laboratory values of vertical coefficients of consolidation. The results of the investigation indicate that the proposed prediction techniques yield reasonable predictions of undrained pore pressure and initial settlement. Additional case studies are required in order to evaluate the predictive methods for the rate and amount of consolidation settlement.
Geotechnical study of an abandoned limestone mine for crude oil storage
Authors: Bawden W. F. , McCreath D. R.
Published: April 2011

The Ironton limestone mine in southern Ohio lies at a depth of approximately 150 m below the surface within the limestones of the Maxville (Mississippian) Formation. The mine was abandoned in 1970 after 60 years of operation. In 1976, the Federal Energy Administration awarded a contract to evaluate the potential of the mine for the storage of crude oil as a part of the U.S. Strategic Oil Storage Program. The paper reviews the geotechnical studies that were undertaken to assess the key questions of whether or not containment of the oil could be assured, and whether or not the mine would remain structurally stable over the life of the storage project.Piezometric data obtained from drilling investigations confirmed that the Maxville limestone, and the over- and underlying formations, were fully saturated. Although some lowering of piezometric levels had occurred over the mine workings, the measured hydrostatic pressures and calculated gradients were found to be sufficiently high to provide positive oil and vapor containment.Based upon in-mine mapping and simple computations, the stability of the mine was determined to be acceptable. It was concluded that bulk oil storage at Ironton mine is technically feasible with minimal costs for remedial geotechnical work.
A new approach to the stability analysis of embankments on sensitive clays
Authors: Trak B. , Rochelle P. La , Tavenas F. , Leroueil S. , Roy M.
Published: April 2011

The new approach to the stability analysis of embankments on sensitive clays, which is presented in this paper, is based on an interpretation of Bjerrum's data made by Mesri, which led to the observation that the available strength at failure under an embankment is nearly independent of the plasticity index and is a function of the preconsolidation pressure of the clay deposit. The new method is found to give good results in sensitive clays, but does not seem to be applicable to soft layered organic, cohesive soils.
Shear strength of the weathered Champlain clay measured in a large diameter triaxial test
Authors: Lafleur J. , Lefebvre G. , Marcotte M. , Silvestri V.
Published: April 2011

This paper describes the sampling procedure and the results of large diameter (150 mm) CID triaxial tests made on samples recovered from the weathered clay crust of the Champlain sea deposits.A visual inspection of the fissures at the depth of sampling (3 m) revealed two types of discontinuities: (a) sub-vertical joints containing black organic matter, spaced approximately every 10 cm, and (b) closed microfissures, randomly distributed in spacing and direction. In order to recover unremoulded samples of this material and avoid a difficult retrimming in the laboratory, a double core barrel 150 mm in diameter (the same as that of the triaxial cell base) was used. Eight compression tests under low confining stresses were made; they showed that the post-peak strength parameters were substantially higher than those back-calculated from a landslide involving the same weathered crust. Examination of the shape of the failure planes and of the stress–strain curves led to the conclusion that, in spite of the large sample size, the propagation of the fractures was controlled by the intact clay matrix rather than by the fissures. Since this was not believed to reproduce the actual field behaviour, a complementary test programme was undertaken, which indicated that the strength parameters were better evaluated from CID tests performed in the normally consolidated range. Keywords: fissured clays, weathering, landslides, triaxial test, shear strength parameters, sampling, back-analysis.
Compaction of alluvial sands by deep blasting
Authors: Solymar Z. V.
Published: April 2011

The Jebba Hydroelectric Development, Nigeria, presently under construction, features a 42 m high zoned rockfill embankment founded on river alluvium up to 70 m in depth. The riverbed alluvium comprises fine- to medium- to coarse-grained, quartzitic sands with traces of gravel. The relative densities of the sands vary appreciably in both the vertical and horizontal directions. During the dam design it was found that it would be necessary to densify the loose to medium dense portion of the river sands to maintain settlements within acceptable limits and to withstand design earthquake forces. The top 25 m of the river alluvium is densified by the vibrocompaction method, and below this level down to depths of 40 m the alluvium is densified by blasting. There is no precedent found in the literature for densification by blasting at such depth. This paper presents details of a test program and the production work. Test results conclusively show increases in static cone penetration resistance in loose sand layers several months after blasting. Keywords: cohesionless soils, compaction, dam foundation, deep blasting, densification (soil), penetration tests, sands.
A study of delayed failure in a cut slope in stiff clay
Authors: Thomson S. , Kjartanson B. H.
Published: April 2011

A first-time, delayed failure occurred in a 7 m deep cut in overconsolidated glacial lake sediments. Remedial work on this landslide allowed a detailed examination of a large part of the slip surface. The backscarp section was readily divisible into two major zones on the basis of macrostructure of the soil. The upper zone was highly fractured and displayed a blocky or nugget structure. The lower zone, while not totally intact, did not display the nugget structure. A third zone in the toe area was subsequently defined. The three zones were sampled and each was described in detail with regard to textural, compositional, and structural features.The samples were tested in triaxial and direct shear tests and the results indicated that relatively distinct strength parameters existed for each zone. The upper and toe zone results were interpreted as having a bimodal failure envelope on a Mohr diagram. Stability analyses were carried out using the strength parameters determined from the testing program. The slope failure may be best accounted for by a slip plane mobilizing virtually zero cohesion with a high angle of shearing resistance in the toe and upper zones and partially softened parameters in the lower or central zone. Key words: delayed failure, shear strength, slope stability, weathering.
Closed-system freezing of soil in earth dams and canals
Authors: Jones Chester W.
Published: April 2011

Field and associated laboratory experiences with closed-system freezing in earth embankment dams and canals are presented. This type of freezing can cause a redistribution of soil density and moisture, which needs to be considered in the design of soil structures used as water barriers in cold regions. Frost-depth measurements made during the winter of 1978–1979 on two earth dams during interruption of their construction and on the Teton Dam remnant in the State of Idaho, U.S.A., are shown, along with associated soil conditions, air-freezing indexes, and insulating effects of snow and, for one dam, a loose soil cover. Some trends of density and moisture changes near the embankment surfaces were established. Keeping in mind known effects of freezing on soils, the paper raises questions about possible changes in soil density and shrinkage of embankments in contact with bedrock abutments that might adversely affect the safety of earth dams.Key words: dams (earth), canals, frost action, frost protection, soil density, soil moisture, soil shrinkage, soil tests, Teton Dam.
Rôle du scellement dans les ancrages actifs scellés dans le rocher
Authors: Ballivy Gérard , Benmokrane Brahim , Aitcin Pierre Claude
Published: April 2011

The dimensioning of anchor bars grouted in rock takes into account the mechanical properties of the three components steel, grout, and rock. The allowable bond strength at the rock–grout interface recommended by different national codes is generally selected according to the type of rocks and assuming an ordinary cement grout. In the present approach, the influence of the type of grout on the pull-out strength of anchor bars in a sound rock mass with mechanical properties equal or higher than the grout is considered. This experimental study shows that certain cement grouts can develop pull-out strength clearly higher than those obtained with epoxy grouts for example. Key words: rock mass, grouted anchors, cement grouts, epoxy grouts, pull-out test, creep test. [Journal translation]
An embankment failure on soft fissured clay
Authors: Crooks J. H. A. , Been K. , Mickleborough B. W. , Dean J. P.
Published: April 2011

Construction at the Genesee Power Project near Edmonton required 13 m high approach fills on soft clay for a roadway overpass structure. During construction, the north approach fill failed at a height of about 12 m. An investigation of the failure was carried out and a monitoring program instigated for further fill construction and piling for the overpass structure.The in situ mass strength of the soft clay was found to be controlled by defects such as slickensides rather than the intact strength. A translational mode of failure is considered most likely to have occurred, with computations based on c′ = 0 and [Formula: see text] determined from normally consolidated samples yielding the appropriate factors of safety to account for the failure. "Tearing" of the fill and overconsolidated crust due to the translational failure mechanism, with associated reduced average shear strengths, also occurred.Monitoring data for construction after the failure are presented and discussed. The effective stress path/yield envelope approach was used to assess the data. An empirical performance criterion for the site was developed for the overpass structure based on the observed deformation rates and computed factors of safety. Key words: embankment, stability, clay, failure, translational failure, effective stress path, fissured.
Field pile load tests in saline permafrost. II. Analysis of results
Authors: Biggar K. W. , Sego D. C.
Published: April 2011

The results obtained from 14 pile load tests carried out in saline permafrost at Iqaluit, Northwest Territories, are analyzed with respect to (i) the development of load along the length of the piles as determined from strain gauges mounted along the embedded portion of the piles; (ii) the time-dependent displacement of the piles under a constant load; and (iii) the performance of grout as a backfill material. The grout used as a backfill material cured adequately and provided sufficient bond strength between the anchor and the grout to cause either the anchor to yield or failure in the surrounding frozen soil. The development of load along the pile resulted in a nearly uniform stress distribution for smooth-surfaced piles but was highly nonuniform when lugs were added. Time-dependent displacement of the piles without lugs can be described using a power-law relationship. Key words : permafrost, saline, pile, load test, field, in situ capacity, load transfer.
Cyclic analysis of axially loaded piles in calcareous soils
Authors: Lee C. Y. , Poulos H. G.
Published: April 2011

This paper describes a simple nonlinear pile-soil interface model incorporated into a modified boundary element analysis to simulate the behaviour of piles in calcareous soils subjected to both static and cyclic loading. A shaft resistance degradation model and a cyclic secant soil modulus degradation model are proposed, and implemented in the nonlinear analysis. Parametric solutions are presented which examine the overall characteristics of axial pile response determined from the nonlinear analysis. Comparisons are made between the theoretical predictions and the measured results of laboratory model tests and published field tests of grouted piles in calcareous soils. These comparisons enable some conclusions to be drawn regarding the suitability of alternative nonlinear analyses. Key words : grouted piles, cyclic loading, calcareous soils, nonlinear analysis.
Effect of fines content on frost heave
Authors: Tester Robert E , Gaskin Paul N
Published: April 2011

In regions of seasonal frost the integrity of pavement structures is dependent on the resistance of base and subbase soils to frost action. This note describes the results of performing the U.S. Army Cold Regions Research and Engineering Laboratory CRREL II laboratory freezing test on a crushed limestone with a varying fines content. Frost heave increased linearly as fines content increased. Under the CRREL frost susceptibility criterion, the crushed gravel was satisfactory with up to 8% fines. A greater fines content resulted in an unsatisfactory classification.

Key words: frost susceptibility, fines content, road base.
Flow slide prediction method: influence of slope geometry
Authors: Stoutjesdijk T P , de Groot M B , Lindenberg J
Published: April 2011

A quasi-two-dimensional method is presented for predicting liquefaction flow slides in a slope with saturated loose sand. The initial stresses at the start of the actual flow slide process are predicted assuming completely drained conditions during the gradual change in slope geometry caused by erosion or sedimentation. The condition for a flow slide is considered to be the presence of at least one sand element in a metastable stress state, i.e., a state in which the undrained response to any quick change in load, however small it may be, consists of a sudden large increase in pore pressure. The metastability of any sand element is predicted as a function of its constitutive properties, its location in the slope, and the slope geometry. The constitutive properties are derived from dry triaxial tests and basically describe the liquefiability (brittleness) of the sand. The metastability criterion for a soil element in a slope is different from that under triaxial loading. Flow slides observed in large-scale tests occurred at the conditions predicted with the model.Key words: loose sand, flow slides, liquefaction, collapse, slope instability.
Consolidation of soil under depth-dependent ramp load
Authors: Zhu Guofu , Yin Jian-Hua
Published: April 2011

This technical note presents a mathematical solution for the consolidation analysis of a soil layer with a change in vertical total stress that varies linearly with depth and time and then remains unchanged after a certain period of time. The solution is described in detail. Results are presented as figures and tables for practical applications.Key words: consolidation, pore-water pressure, average degree of consolidation, total stress, clay, soil.
Note: Natural heavy-metal release by sulphide oxidation in the High Arctic
Authors: Elberling Bo , Langdahl Bjarne Riis
Published: April 2011

An assessment of the environmental impact of the weathering of sulphide-rich rocks at Citronen Fjord, North Greenland, provided information on sulphide oxidation rates and metal release from outcrops of sediment-hosted, stratiform ore that may be mined for its zinc content. In situ oxygen uptake rates were measured at the surface of partly weathered sulphide-rich outcrops and compared with metal contents in streams and soil water. The oxygen uptake rates measured during August 1996 were of the same order of magnitude as those reported from mine tailings at lower latitudes. The variation in metal concentrations and pH of the drainage waters reflects the spatial variation in sulphide oxidation and carbonate buffering. High weathering rates of sulphide minerals occur in the High Arctic during the summer, and release of heavy metals must be considered a potential environmental issue if mining is initiated.Key words: sulphide oxidation, pyrite, sphalerite, oxygen, High Arctic, zinc.
Experimental investigation of shell foundations on dry sand
Authors: Hanna Adel , Abdel-Rahman Mohamed
Published: April 2011

Shells are usually used as structural elements in buildings. In Germany they showed remarkable resistance to the effects of bombing during World War II. About 1 decade later, the possibility of employing shells in foundation engineering was explored. Surveys of the literature indicate that shell foundations have been employed effectively in different parts of the world and were proven to provide an overall economical alternative to the conventional flat foundations. However, the geotechnical design of these footings remained the same as for their respective flat ones. Accordingly, the advantages of shell geometry in foundation engineering has not yet been explored in the design of these footings. The objective of the present study is to examine the overall geotechnical behavior of three types of shell foundations resting on sand under axial loading conditions, namely, triangular, conical, and pyramidal shells. Furthermore, the resulting bearing capacities and settlements will be compared with conventional strip, circular, and square flat foundations. The present paper presents an experimental study on nine foundation models tested on loose, medium, and dense sand states. The influence of shell configuration and embedment depth on the ultimate bearing capacity and settlement will be presented. The results of the present experimental investigation have shown the admirable performance of shell foundations with respect to ultimate bearing capacity and settlement characteristics. Shell foundations provide higher resistance to lateral loading as compared with flat ones, and thus they will perform better in earthquake regions.Key words: shell foundation, experimental investigation, bearing capacity, settlement, sand, geotechnical engineering.
Hydrogeology of a thick clay till and Cretaceous clay sequence, Saskatchewan, Canada
Authors: Shaw R Joel , Hendry M Jim
Published: April 2011

Clay-rich glacial till and Cretaceous clay are common throughout the Interior Plains of North America. Quantifying groundwater flow through these aquitards has implications for solute transport in aquitards and protection of underlying aquifers. Groundwater flow through a two-tiered aquitard system was investigated using laboratory and field methods at a test site in Saskatchewan, Canada. The aquitard system consists of 80 m of uniform, plastic clay-rich Battleford till (deposited 12-18 ka BP) disconformably overlying 77 m of late Cretaceous plastic marine clay (Snakebite Member, deposited 70-72 Ma BP). The upper 3-4 m of till is oxidized and fractured whereas the remainder is unoxidized. For the scales investigated, results suggested that hydraulic conductivity, K, is independent of scale for relatively thick till and clay bedrock deposits. Analysis of slug tests in the unoxidized till and laboratory tests on cores of unoxidized till yielded geometric mean K values of 5.4 × 10-11 and 2.7 × 10-11 m/s, respectively. Laboratory K tests of clay samples yielded a geometric mean K of 4.3 × 10-12 m/s. Bulk K of the clay was estimated to be 2.3 × 10-12 m/s assuming steady-state flow through the till and clay. The present-day groundwater velocity through the aquitard system was estimated to be between 0.5 and 0.8 m/10 ka downward based on the measured K values, measured hydraulic gradients, and measured porosities. Results suggested that pore water in much of the till was introduced during or shortly after glaciation.Key words: hydrogeology, aquitards, Cretaceous clay, Battleford till, hydrogeologic properties, geotechnical properties.
Physical and mechanical properties of a compacted silty sand with low bentonite fraction
Authors: de Magistris Filippo Santucci , Silvestri Francesco , Vinale Filippo
Published: April 2011

Compacted granular soils with small additions of bentonite have been used to build geotechnical structures such as impervious liners and cores of zoned earth dams. This paper presents a laboratory study showing how physical and mechanical characteristics of a silty sand are modified by a low percentage of bentonite. The effects of the addition of bentonite on the silty sand are reflected by an increase in the plasticity index, a reduction in maximum modified Proctor density, and a decrease in hydraulic conductivity. The most significant consequences on the mechanical properties are an increase of compressibility and secondary consolidation coefficients, and a reduction in shear strength. Different mixtures were either dynamically compacted at the optimum water content (compacted samples) or prepared after slurry consolidation from the minimum density (remoulded samples). Although the compacted and remoulded specimens show different isotropic compression lines, their critical-state lines in the v:p':q space are identical, where v is specific volume, p' is average effective stress, and q is deviator stress. Comparisons of the mechanical parameters with the existing literature database show that the compression coefficients of the remoulded mixtures are comparable to those of normally consolidated clayey soils of similar plasticity; nevertheless, those of the compacted mixtures are considerably lower. Also, the slopes of their critical-state lines in the q:p' plane are in good agreement with those predicted by empirical correlations for fine-grained soils.Key words: bentonite, silty sand, compaction, physical properties, compressibility, critical state.
Écoulement à surface libre dans un massif de sol soumis à la marée : comparaison théorie-expérimentation
Authors: Rezzoug A , Alexis A , Thomas P
Published: April 2011

We analyze analytically and numerically the stress distribution along the plug-rock interface and within an axially loaded plug emplaced in a borehole in rock. Experiments show that the interface strength increases with decreasing plug radius and with increasing plug length. Axial strength decreases as a power law of plug radius. An increase in the modulus ratio (ratio of plug modulus to rock modulus) increases the interface strength, until it levels off at a ratio of about 5.0. For short plugs, the tensile stresses may reach a magnitude significant to be of concern for long-term stability of the plug and of the host rock. Out studies suggest designing friction plugs with a length to radius ratio of at least 8.0. In practice, especially for short-term performance, e.g., emergency flood control or temporary diversions, a ratio of 8.0 may not be necessary or justified. For permanent abandonment plugs, it is essential to reduce the tensile stresses in the plug and in the host rock to a level that will minimize the risk of long-term deterioration. We recommend in situ experiments on larger diameter plugs to assess the validity of the proposed size effect extrapolation obtained in this study. Key words: borehole plugging (sealing), shaft seal design, plug-rock interface strength, axial strength, bond strength, cement grout.
Diffusion and adsorption of benzene in Regina clay
Authors: Donahue Robert B , Barbour S Lee , Headley John V
Published: April 2011

The diffusion and adsorption coefficients for benzene were measured for a glaciolacustrine clay using the single- and double-reservoir methods, batch tests, and organic carbon content correlations. Single- and double-reservoir diffusion test cells and experimental procedures were specifically developed for volatile organic chemicals. Analytical methods based on solvent extraction with gas chromatography - flame ionization detection and purge and trap gas chromatography - mass spectrometry were used for the analysis of aqueous benzene solutions in the 0.5 µg/L to 500 mg/L range. The measured effective diffusion coefficient was 0.01 m2/a (3.2 × 10-6 cm2/s), and adsorption coefficients ranged from 0.1 to 1.0 mL/g. The diffusion cell tests indicate relatively low levels of retardation for benzene as it moves in clay soils with low organic carbon content.Key words: adsorption, diffusion, benzene, Regina clay.
Uplift behaviour of tapered piles established from model tests
Authors: El Naggar M Hesham , Wei Jin Qi
Published: April 2011

Tapered piles have a substantial advantage with regard to their load-carrying capacity in the downward frictional mode. The uplift performance of tapered piles, however, has not been fully understood. This paper describes the results of an experimental investigation into the characteristics of the uplift performance of tapered piles. Three instrumented steel piles with different degrees of taper were installed in cohesionless soil and subjected to compressive and tensile load tests. The soil was contained in a steel soil chamber and pressurized using an air bladder to facilitate modelling the confining pressures pertinent to larger embedment depths. The results of this study indicated that the pile axial uplift capacity increased with an increase in the confining pressure for all piles examined in this study. The ratios of uplift to compressive load for tapered piles were less than those for straight piles of the same length and average embedded diameter. The uplift capacity of tapered piles was found to be comparable to that of straight-sided wall piles at higher confining pressure values, suggesting that the performance of actual tapered piles (with greater length) would be comparable to that of straight-sided wall piles. Also, the results indicated that residual stresses developed during the compressive loading phase and their effect were more significant on the initial uplift capacity of piles, and this effect was more pronounced for tapered piles in medium-dense sand.Key words: tapered piles, uplift, axial response, load transfer, experimental modelling.
Reliability evaluation of shallow foundation bearing capacity onc' ϕ' soils
Authors: Cherubini C
Published: April 2011

As our understanding of soils has been steadily improving, the characteristics of its variability can now be highlighted. This has practically changed our geotechnical modus operandi from strictly deterministic models to semiprobabilistic or even strictly probabilistic models. The latter are still to be regarded as experimental and cannot, for the time being, be used routinely in practical working applications. However, the ongoing, continued research and study of these methods combine to develop their worth and bring out any drawbacks. This paper proposes a possible application of probabilistic methods to the study of shallow foundations reliability with respect to their bearing capacity. The study concerns a foundation on a soil characterized by effective cohesion c' and friction angle ϕ', considering possible values of correlation coefficients between them and taking into account the effects of vertical fluctuation scale. The results show that higher reliability indexes are found when correlations between c' and ϕ' are negative and when the fluctuation scale has a minimum value.Key words: reliability, bearing capacity, shallow foundations, friction angle, cohesion.
On the thermal consolidation of Boom clay
Authors: Delage Pierre , Sultan Nabil , Cui Yu Jun
Published: April 2011

When a mass of saturated clay is heated, as in the case of host soils surrounding nuclear waste disposal at great depth, the thermal expansion of the constituents generates excess pore pressures. The mass of clay is submitted to gradients of pore pressure and temperature, hydraulic and thermal flows, and changes in its mechanical properties. In this work, some of these aspects were experimentally studied in the case of Boom clay to help predict the response of the soil, in relation to investigations in the Belgian underground laboratory at Mol. Results of slow-heating tests with careful volume change measurements showed that a reasonable prediction of the thermal expansion of the clay-water system was obtained by using the thermal properties of free water. Despite the density of Boom clay, no significant effect of water adsorption was observed. The thermal consolidation of Boom clay was studied through fast-heating tests. A simple analysis shows that the hydraulic and thermal transfers are uncoupled. Experimental results from fast-heating tests showed that the consolidation coefficient does not change significantly with increased temperature, due to the opposite effect of increasing permeability and decreasing porosity. The changes of permeability with temperature were investigated by running constant head measurements at various temperatures. An indirect analysis, based on estimation of the coefficient of volume change mv, showed that the indirect method of estimating the permeability from consolidation tests should be considered carefully. Intrinsic permeability values were derived by considering the change of the viscosity of free water with temperature. A unique relationship between the intrinsic permeability and the porosity was observed, with no dependence on temperature, confirming that the flow involved in the permeability test only concerns free water.Key words: clays, thermal consolidation, adsorbed water, permeability, temperature effects, radioactive waste disposal.
Synthesis and structural characterization of zirconium complexes containing aminodiolate ligands and their use as Lewis acid catalysts
Authors: Shao Pengcheng , Gendron Roland AL , Berg David J
Published: April 2011

A series of aminodiols RN(CH2CH2C(OH)Rprime2)2 (R, Rprime = Me, Me 4; Me, Ph 5; tert-butyl, Me 6; tert-Bu, Ph 7; (S)-PhCH(Me), Me 8) were prepared by the Michael addition of a primary amine to methyl acrylate followed by reaction of the resulting aminodiester with excess methyl or phenyl lithium. Reaction of two equivalents of the aminodiols 4-8 with tetrabenzylzirconium afforded the zirconium bis(aminodiolates) 10-14 in excellent yield. Complex 11 (R, Rprime = Me, Ph) adopts a cis, fac-octahedral geometry in solution and in the solid state. Complexes 10-14 are fluxional in solution by NMR spectroscopy: small substituents at nitrogen and large substituents at the alkoxide carbons slow the rate of exchange. The chiral complex 14 functions as a Lewis acid catalyst in the nitroaldol (Henry) reaction and the oxidation of geraniol by tert-butyl hydroperoxide with modest enantioselectivities (30 and 46% enantiomeric excess (ee), respectively).Key words: diol, Michael addition, zirconium, synthesis, structure, fluxional, alkoxide, Lewis acid, catalysis.
1999 Alfred Bader Award Lecture From early developments in multi-step organic synthesis on solid phases to multi-nuclear phthalocyanines
Authors: Leznoff Clifford C
Published: April 2011

Early developments in solid phase organic synthesis are traced. Particular emphasis is placed on the use of cross-linked polystyrene in the first general method of monoblocking symmetrical difunctional compounds. The monoprotected polymer-bound symmetrical starting materials were then used in multi-step syntheses of a variety of compounds, particularly insect pheromones. Asymmetric synthesis on polymer supports was demonstrated. Diels-Alder and 1,3-dipolar additions on polymer supports proceeded readily as did macrocyclic formation of porphyrins and phthalocyanines. All of these reactions clearly showed that most organic chemical reactions could be performed on solid phases and laid the basis for the development of combinatorial chemistry. The first unsymmetrical phthalocyanine was prepared using the solid phase method and this led eventually to solution phase methods of preparing bi-, tri-, tetra-, and even a dendritic-like pentanuclear phthalocyanine.Key Words: solid phase organic synthesis (SPOS), phthalocyanines.
42-crown-14-based [2]catenane
Authors: Gibson Harry W , Lee Sang-Hun
Published: April 2011

A compound isolated from a synthesis directed toward 42-crown-14 (42C14) has been purified and characterized by means of IR, HPLC, NMR, MS, and DSC techniques. Its infrared spectrum contains no OH, tosylate, or unsaturated unit signals. The HPLC retention time of the compound differs from that of "42C14" and other crown ethers examined. The chemical shifts of the singlets in the 1H and 13C NMR spectra differ from those of poly(ethylene oxide)s (PEOs), and crown ethers. The FAB mass spectra contain signals attributable to a compound with twice the mass of 42C14 and the fragmentation pattern is consistent with [2]catenane 9 based on interlocked 42C14 units, because the next major signals generally correspond to 42C14 and its adducts. The DSC results showed that the compound, a colorless wax at room temperature, was amorphous with a glass transition temperature which was 80° higher than those of aliphatic crown ethers, which are crystalline compounds with melting points >40°C. Considering the high yield of the compound (8% in the reaction mixture as determined by NMR, 1.7% isolated), it is believed that sodium cation-crown ether-linear ether complexation was involved in templating its formation. Evidence for such complexation was also observed in the FAB MS.Key words: catenanes, crown compounds, macrocycles, template synthesis, rotaxanes.
Multidimensional conformational analysis of allyl methyl disulfide: a key component of garlic
Authors: Lin Alvin C , Salpietro Salvatore J , Deretey Eugen , Csizmadia Imre G
Published: April 2011

Organosulfur compounds in garlic, like allyl methyl disulfide, have been found to be involved in antimutagenic, anticarcinogenic, antithrombotic, and lipid-lowering activities, and it has also been found to act as an antioxidant. Ab initio molecular computations were performed on dihydrogen disulfide (1) with respect to torsional angle τ1 = τ(H·S-S·H), hydrogen methyl disulfide (2) with respect to torsional angle τ1 = τ(H·S-S·CH3), and allyl methyl disulfide (3) with respect to torsional angles τ1 = τ(H3C2·CH2·S-S·CH3), τ2 = τ(H3C2·CH2-S·S·CH3), and τ3 = τ(H3C2-CH2·S·S·CH3). Potential energy curves (PEC) were obtained from 1 and 2, i.e., E = E(τ1), from which optimized structures were obtained at the HF/6-31G* level of theory. These optimized structures were used to investigate the potential energy hypersurface surface (PEHS) of 3, i.e., E = E(τ1,τ2,τ3). One-dimensional scans along τ2 and τ3 (where τ1 = ±90°; τ1 = 180°) were performed at the HF/3-21G* level of theory. From these scans, six lower energy pairs of enantiomeric minima (i.e., [g+g+g+| g-g-g-], [g+ag- | g-ag+], [g+g-g+ | g-g+g-], [g+g+g-| g-g-g+], [g+ag- | g-ag+], and [g+g-g-| g-g+g+]) as well as 3 higher energy minima (i.e., [g+g+s | g-g-s], [g+as | g-as], and [g+g-s | g-g+s]) were optimized at τ1 = ±90° at the HF/6-31G* and B3LYP/6-31G* levels of theory. The global minimum was determined to be the [g+g-g+ | g-g+g-] enantiomeric pair of conformers, and the fully symmetrical anti-anti-anti [a a a] structure was determined to be a second-order saddle point on the PEHS of 3. Although there are no stereocentres in 3, there is chirality in the conformational twist with respect to the [a a a] conformation through τ1 = τ2 = τ3 = 180°. Based on the energies and MO diagrams of the HUMO and LUMO +1 of 3, the anticarcinogenic and cholesterol lowering activity mechanism of 3 is presented.Key words: ab initio MO computations, allyl methyl disulfide, multidimensional conformational analysis (MDCA), anticarcinogenic, cholesterol lowering.