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By L. B. Khershberg

Marginal seas of the Russian Far East constitute the northwestern segment of the Pacific underwater belt distinguished by distinct metallogenic specialization of shelf-extended ore-bearing magmatic complexes and associated polycyclic mineralization. The coastal part of this vast region is known to contain both multiple placer manifestations and deposits, and non-metalliferous minerals. The latter are sedimentary deposits, the products of weathering, which contain re-deposited placer minerals in industrial concentrations developed on the shelf by certain geological processes. The shelf part of the Far Eastern seas is a seawater-filled continental margin. Complex geophysical mapping and drilling from ships of shelf sedimentary thickness and foundation has revealed the units of contemporary and ancient relief accompanied by formation of industrial concentrations of placer gold, cassiterite, titanium-magnetite, zircon, monzonite, and other components at different stages of placer formation. According to the information collected by prospecting by ?Dalmorgeologia? Co. Ltd. and other companies, placer-host structures within trans-placer-concentrating structures (land-shelf) are: shelf-extended river plains, contemporary and ancient shorelines, beaches, drained areas, spits, bars, detritus deficit zones, and terraces and bodies accumulated underwater in the areas where along-shoreline flows unload their detritus. They all could be used as criteria/signs for mapping and targets for placer prospecting.

Jan 1, 2004

By P. Trudel, M. A. . Cloutier

This lithogeochemical study demonstrates that the Gilman and Blondeau Formations in the Chibougamau area belong to a subalkaline suite of tholeiitic affinity poor in potassium. The Gilman Formation is composed mostly of basalts, with subordinate andesites and rare dacites, while the Blondeau Formation comprises all lithologies of the basalt-andesite-dacite-rhyodacite-rhyolite ensemble. Both AFM and Harker variation diagrams show that all these rocks originated by differentiation from the same magma reservoir, and are related to one volcanic episode, This study did not, however, identify hydrothermal alteration zones useful for regional geochemical prospect ion.

Jan 1, 1984

By Douglas J. Harvey

The surface tension of lead-tellurium alloys (in the range 0 to 6.70 at. pct Te) ad lead-arsenic alloys (in the range 0 to 10.53 at. pct As) has been examined by the maximum bubble pressure method. The surface tension of high purity lead can be expressed over a range of temperatures (M.P. to 750°C) by the relationship = 512 — 0.133t. Arsenic and lellurium were both found to be surface active in lead. The surface excess concentration at 700°C was .found to be constant at 0.74 x 10-10 moles per sq cm for tellurium. The surface excess of arsenic at 700°C varied between 0.26 x 10-10 moles per sq cm at 0.16 at. pct to 1.5 x 10-10 moles per sq cm at 8.3 at. pet. The surface tension of lead has been investigated sporadically over the last 90 years. The first recorded study was made by Quincke1 who used a rather crude application of the drop-weight method. Hogness2 obtained the first reliable value for the surface tension of lead by measuring the pressure necessary to force the liquid metal from the end of a small capillary of known radius. Hogness gives the empirical formula: ?(surface tension)= 444 - 0.077 (l-327) which describes the relationship between surface tension and temperature ("C); This work was followed by that of Bircumshaw3 who applied the two-capillar maximum bubble pressure method of Sugden.4 The values published by Bircumshaw are in good agreement with those found by Hogness. Matuyama5 examined the surface tension of lead by the drop weight method. However, the values found are somewhat higher than those previously reported. More recent investigations by Greenaway6 and by Melford and oar' have resulted in data which are not in close agreement, but which are well within the expected range at most temperature levels. The study of the surface tension of lead alloys began with Drath and sauerwald8 who examined the lead-bismuth system. They found that the surface tension values of the alloys in this system deviated only slightly from the ideal mixture rule. Matuyarna5 examined the lead-antimony system. Bircumshaw the lead-tin, and the lead-indium system was studied by Hoar and Me1ford.10 The results of these investi- gations are summarized in Fig. 1. It may be seen that the data vary only slightly from the ideal mixture rule. As none of the metals studied and reported in the literature has a very interesting effect on the surface tension of lead,*the next logical step might be to examine the effect of metals of low solubility or nonmetals having some liquid solubility. Baes, and Kellogg11 have pointed out that the elements most likely to be surface active in liquid metals are ones of limited solubility in the liquid state and possessing weak intermolecular bonding forces in the solid state. Therefore, Group V, VI and VII nonmetals are most likely to be surface active. It was decided to examine the effect of a borderline metal, arsenic, and a nonmetal tellurium. Arsenic forms a eutectic with lead having a melting point of 290°C and a composition of 6.9 at. pct As.13 Pure arsenic sublimes when heated above 610°C. Even though alloying with lead lowers the vapor pressure, fumes containing arsenic are evolved at a very noticeable rate when lead-arsenic alloys are heated above 650°C. Tellurium raises the liquidus temperature of lead sharply to 904°C,14 the melting point of PbTe (lead-telluride). The solid solubility of tellurium in lead was determined by Greenwood and worner15 to be 0.0007 at. pct at room temperature. EXPERIMENTAL METHOD Surface Tension Measurement—The two capillary maximum bubble pressure method for measuring surface tension developed by Sugden,4 and used later

Jan 1, 1962

By Jeff Easton, J Johnson, D. Foot

The Mina Santa Rosa mine in Panama was the victim of a mine closure 24 years ago that left the community in dire straits. The mine showed the potential resources of greater than 1M ounces of gold and 4.5M ounces of silver. Veragold Mining Company decided to reopen the mine and address all the issues that were involved in the startup of an historic mine. This paper provides methods to restore the community trust, provide a transparent process, and develop an environmentally sound flowsheet. Immense scrutiny surrounded the Tailings Storage Facility, and the company developed a plan focused on paste thickening and surface stacking to eliminate the need for a conventional tailings’ facility. Paste thickener principles and benefits are also provided.

Feb 1, 2024

To reduce operator exposure to drilling noise from roof bolting machines. Background Noise-induced hearing loss (NIHL) is a prevalent occupational illness in the United States. Studies indicate that 70%?90% of miners have NIHL significant enough to be classified as a hearing disability. Mine Safety and Health Administration studies indicated that roof bolting machine operators are among those overexposed to noise. Field studies support the premise that, on average, drilling is the loudest noise source to which a roof bolting machine operator is typically exposed and contributes greatly to the operator?s noise exposure. The National Institute for Occupational Safety and Health (NIOSH) has further determined that the drill steel and chuck radiate a significant amount of noise during drilling. To address this noise hazard, NIOSH developed a collapsible drill steel enclosure (CDSE) to encapsulate the drill steel during the drilling portion of the roof bolting machine duty cycle. In addition, NIOSH is collaborating with J. H. Fletcher & Co. in the continued development of a CDSE.

Sep 1, 2008

By M. Solomon

Crushers are designed and manufactured to survive the severe duty of mining environments worldwide. Under these conditions the crusher performance and availability is one of the critical factors in the mine?s production and profitability. Traditionally the development of these machines tends to be experience-based, incremental improvements in design due to challenges of different applications, duty, or manufacturing. In order to better serve the mining industry a new approach was taken to the design of primary crushers. This approach was to focus on safety and maintenance activities. The result of this effort is a new generation of gyratory crushers that can be serviced from above. Using the features of this new generation of crushers to their fullest extent crushing installations have improved safety, reduced design and construction costs, and lowered maintenance requirements. This presentation explores the benefits of two crusher installations utilizing top service crushers.

Jan 1, 2010

By Charles Catlett

The terms " developed " and " undeveloped " are necessarily relative and cover a wide range; but the latter is here applied to cases in which the information at hand falls short of a clear demonstration of values, and conclusions must be reached frorn a study of the geological conditions of the particular deposit, interpreted in the light of similar and closely-related deposits. Such an inquiry might be characterized as an effort to reach reliable conclusions from insufficient data. But the engineer

Jan 1, 1909

By S. D. Thompson, L. Adler

This study reviews and analyzes the empirical methods available for designing the capacities of coal mine gathering belts. The analyses lead to recommendations concerning the application and implementation of each empirical method. Operations research techniques, mainly simulation models, are also briefly mentioned, and a few recommendations are made concerning their selection and application. The objective of the study is to provide a reliable basis for the practicing engineer to properly select, apply, and implement a capacity design method.

Jan 1, 1988

By C. W. Robinson

Transportation is the minerals business. Once upon a time the geologist, the engineer and later the metallurgist reigned supreme, but the leading role in mineral development today is the economist-especially the transportation economist. Obviously this trend is more important for large volume, low value mine-to-market movements of such commodities as iron ore, phosphate, potash, coal and petroleum. But, transportation is of sufficient importance to all mining activities to be included in forward planning. Civilization has been influenced by transportation developments to an extent little understood or appreciated. Although industrialists are capable of intelligent historical analysis of this phenomenon, too frequently they have failed to project, or anticipate those changes in transportation techniques which will influence the pattern of industrial growth.

Jan 1, 1971

To reduce operator exposure to noise from vibrating screens at coal preparation plants. Background Hearing loss is one of the most common occupational illnesses in the United States. In the U.S. mining industry, hearing loss is 2.5 to 3 times greater than what is expected for the average population that is not exposed to occupational noise. Furthermore, studies by the National Institute for Occupational Safety and Health (NIOSH) showed that by age 50, 90% of coal miners have a hearing impairment versus only 10% of the population that is not exposed to occupational noise. A NIOSH cross-sectional survey of coal preparation plants showed that 43.5% of employees were overexposed to noise. The study also found that vibrating screens were one of the top five loudest types of equipment at these plants?as well as the most numerous?making them a key noise source to address.

Nov 1, 2009

By J. K. Kerver, J. S. Osoba, J. G. Richardson, J. A. Hafford

A detailed study of a number of methods of relative permea-abilitv measurement has been made in a search for the tech-niqrle most suited to routine analysis of cores taken from reservoir rock. It has been found from tests run on the same samples of core material by a number of techniques that the Penn State, Hassler, Hafford, and dispersed feed techniques all yield results which are felt to be reliable. Conditions under which the faster single core dynamic technique may be used are described. Further work on the calculation of relative permeabilities to oil from data obtained by the gas drive method is needed before this latter rapid method can be utilized. Correlations between theoretical studies and experimental results have been obtained in studies of the boundary effect. pressure distribution in two-phase flow, and gas expansion effects. Previous conclusions that the effects of the outflow boundary could be made negligibly small have been substantiated. Results of experimentally determined oil and gas pressure distributions along a core sample during flow are presented. Further studies of the effects of rate of flow in the measurement of relative permeability-saturation relations have shown that results are independent of the rate of flow as long as the flow rate is below the point where inertial effects commence. An analysis of the effects of a severalfold expansion of gas along the flow path indicates that while saturation gradients are induced in the test sample, the errors caused by this phenomenon in relative permeability measurements are small. INTRODUCTION Many pages of literature have been devoted to pointing out the need for relative permeability-saturation relations in reservoir engineering. One of the most attractive ways of obtaining this information is by the analysis of samples of core material taken from the formation in question, and again literature has described man); methods for obtaining these data. It is the purpose of this paper to present the work that has been done in the study of some of these published methods together with some other methods that have been recently developed in this laboratory. Also, a study of some of the factors that influence the laburatory determination of relative permeability-saturation relations is presented. FACTORS WHICH AFFECT LABORATORY STUDY OF FLUID FLOW THROUGH RESERVOIR ROCK To determine relative permeability-saturation relations of samples of reservoir rock in the laboratory, it is important to know what factors affect these measurements in order that the magnitude of these effects can be ascertained and steps then can be taken to eliminate or, in some cases, to minimize them. The factors that have been investigated are the boundary effect, the effect of gas expansion. and the rate effect. Boundary Effect In laboratory experiments in which two immiscible fluids are flowed through a porous medium, there exists a discontinuity of capillary properties at the outflow face. This discontinuity exists became the fluids pass from a region of finite capillary pressure in the sample to a region of zero capillary pressure in an open receiving vessel. The capillary forces existing in the core caupe the rock to tend to retain

Jan 1, 1952

By J. H. E. Jeffes, K. T. Jacob

The activity coefficients of oxygen in liquid Pb-Sn alloys have been measured between 550 and 1100°C by use of solid oxide galvanic cells: Pt, Ni-NiO | Zr02 Solid electrolyte | O (Pb + Sn), Cermet, Pt; and Pt, Fe-FeO | Zr02 Solid electrolyte | 0(Pb + Sn), Cermet, Pt. Alcock and Richardson's quasi-chemical equation, with the coordination number of atoms set to 2, is found to predict successfully the activity coefficients of oxygen in these alloys. The relative partial molar enthalpy and entropy of oxygen at 1 atom per cent in the alloys have been calculated from the variation of the activity coefficient with temperature. The addition of Sn to an unsaturated solution of O in Pb is shown to decrease significantly both the partial molar enthalpy and entropy of O. As the measurements were restricted to a narrow range between 750 and 1100°C in Pb-rich alloys, however, the pronounced variation of the partial molar enthalpy of O with temperature at constant alloy composition predicted by the quasi-chemical model could not be verified.

Dec 1, 1971

By Chris McBean

Due diligence mistakes ? lost opportunity ? High profile write-downs and cost overruns ? Result ? tight market for financing ? Implications for due diligence ? need to get it right ? maybe only one chance ? Where should focus be?

May 1, 2013

By Paul A. Beck, M. N. Parthasarathi

By determining the (220) pole figure for OFHC copper rolled to 96 pct R. .A., the occurrence of four texture components of the type (135) [211] was confirmed. It was found that the total volume fraction of material close to the four symmetrical orientations of this type is larger than the volume fraction of the other components put together. THE rolling texture of copper was described by early investigators1'" as a mixture of components of the (110)[l12] and (112) [11l] types. Other studies, still using the qualitative photographic method of texture determination arrived, instead, at orientations of the type (135) [533] or (135) [211] for copper3'4 and at the closely related "Z-texture" for a fee nickel-iron alloy.5 The prevalence of this type of orientation, near (123) [412], in the rolling texture of aluminum and of copper was later confirmed by means of quantitative diffractometer methods.' However, in a recent paper7 Jones and Fell stated that the (110) [112] and (112) [111] double texture was in better agreement with the measurements of Young's modulus for cold-rolled copper.' These authors also expressed their belief that the "roll texture" can be determined by means of two photographic quasi-fiber texture patterns taken with sheet specimens rotated around the rolling direction and the transverse direction, respectively. Jones and Fell found7 that the results obtained from such patterns for cold-rolled nickel did not agree with any of the orientations mentioned above, but they suggested that the observed diffraction spots may have been brought about by the overlapping of reflections due to the (110) [112] and (112) [11l] double texture components. Jones and Fell concluded that the (123) 14121 type orientation is inconsistent with their patterns. They also stated, without offering any supporting evidence, that this orientation is inconsistent with the (220) pole figure. "Ideal orientations" are often used for a very rough description of the principal orientations encountered in a texture, It is, however, well to remember the fact that, no matter how "accurate", these ideal orientations are only schematic representatives of a continuous distribution9, which often (as in the case of rolled copper) includes extensive orientation spreads. The attempt by Jones and Fell7 to use elastic modulus data in deciding between various ideal orientations in the rolling texture of copper neglects this fact. The inadequacy of two-dimensional "axis density figures" in describing orientation distributions in sheet textures was previously discussed.9 It was also pointed out9 that there is no reliable evidence to prove that orientation distributions derived by the "quasi-fiber method" from rotated sheet specimens are fully equivalent to the corresponding information obtainable from quantitative pole figures. The view that a sheet texture could be adequately determined by means of two photographic quasi-fiber texture patterns is obviously erroneous9. The question as to the consistency with the (220) pole figure of ideal orientations derived from the (111) and (200) pole figures is, on the other hand, certainly very relevant. Since no quantitative (220) pole figure for cold-rolled copper appears to be available in the literature, the following work was undertaken. EXPERIMENTAL METHOD An extruded rod of OFHC copper, 1 in. in diam, was given alternate rolling (30 to 35 pct R.A.) and

Jan 1, 1962

By AIME AIME

THE Institute of Metals Division of this Institute held a joint meeting with the American Foundry- men's Association on Oct. 5-9, at Syracuse, N. Y. The registration at this meeting was about 150. There were four meetings in all, three of which were in con- junction with the American Foundrymen's Association. This combination works out very nicely and gives the I Division a number of practical foundry papers that it would not get otherwise. The sessions were well attended and the discussion was active. The session on Monday morning was of a general nature and consisted of the following subjects : " Refractory Problems in the Non-ferrous Electric Furnace Casting Shop, " "Temperature Control of Non-ferrous Alloys," "Atomized Coal System of Non-ferrous Melting," "Material Handling in a Brass Foundry." On Tuesday morning, the session was on "Aluminum and Its Alloys." The paper on permanent mold castings created a large amount of discussion, in fact so much that it had to be renewed after the close of the regular program. Aluminum is assuming a more important place every year and adds greatly to the program as a whole. One of the most remarkable meetings that this Division has ever had was held on Tuesday at noon in the form of a Round Table discussion, headed by G. K. Elliott, chairman of the Division, Cincinnati, Ohio. Mr. Elliott divided the members present, numbering about 80, into groups as they were seated at the tables. Each of these groups suggested a topic for discussion. They were as follows : "Fluxes on Market ;" "Simplification of Alloys;" "Pyrometric Control;" "Effect of Gas- sing Metal and Control;" "Barium Sulfate Added to Electric Furnace to Create Slight Oxidation to Remove Aluminum and Silicon;" and" Nickel in Brass."

Jan 1, 1925

By W. L. Prehn, Adele Chambers, R. L. Slobod

The centrifuge has been found to be an extremely useful tool for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. The use of the centrifuge for determining the properties of small core plugs has been discussed in the literature,',' but practically no experimental evidence has been presented justifying the use of this method in preference to other methods (mainly disc method) now in use. Data have been accumulated and are now presented demonstrating the advantages of the centrifugal method, some of which are: (1) rapid establishment of equilibrium, (2) excellent precision yielding very reproducible results, (3) availability of high pressure differences between phases, (4) simple operational procedure, and (5) ability to establish connate water, residual oil, or to obtain complete capillary pressure curve in one day or less. A commercially available centrifuge capable of speeds up to 3,800 rpm, and a high speed attachment providing a maximum rate of rotation of 18,000 rpm were used in this work in conjunction with core holding tubes designed specifically for this application. In view of the outstanding advantages associated with the use of the centrifuge the conclusion has been drawn that this method should be used in place of the more tedious, slower, and less reliable disc method for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. INTRODUCTION The need for accurate values of connate water, residual oil, and capillary pressure curves in reservoir engineering has been recognized for many years, and the extent of the effort devoted toward solving these problems is reflected in the large number of papers3-" which have appeared in the literature during the past decade. Most of the methods discussed in the recent literature employ a porous disc as a semi-permeable membrane to separate two immiscible phases and make pos-ible the application of an explicit difference in pressure between two phases in the core. Thus, in the determination of the capillary pressure curve the wetting phase (water) is displaced by the non-wetting phase (air or oil). Several investigators1,2 have used centrifugal forces to develop pressure differences between phases. As a result of the first work' in this field the conclusion was reached that "the more rapid centrifugal method for measuring irreducible saturation may have equal value, (compared to use of discs) but more work is required to establish this point." This work was followed in 1945 by a more detailed study2 in which the concepts of this experimental work were more clearly enunciated. A method for calculating saturation for any given speed of rotation based on the observed volume of water displaced was developed and a wider application of the method was suggested. The absence of any subsequent pertinent literature on this subject is interpreted as indicating that no additional work has been completed to substantiate or deny the earlier claims and suggestions of promise contained in the original papers on this subject. One purpose of this report is to provide evidence designed to establish the practical value of centrifugal methods in determining core properties such as connate water and capillary pressure curves. It is also our purpose to suggest a broadening of the scope of this tool to include determinations of residual oil by gas or water drives. THEORY AND PRACTICE IN USE OF CENTRIFUGE Hassler and Brunner2 have clearly presented the basic concepts involved in the use of the centrifuge by relating the performance of a small core in a field of high acceleration to the

Jan 1, 1951

By R. L. Slobod, W. L. Prehn, Adele Chambers

The centrifuge has been found to be an extremely useful tool for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. The use of the centrifuge for determining the properties of small core plugs has been discussed in the literature,',' but practically no experimental evidence has been presented justifying the use of this method in preference to other methods (mainly disc method) now in use. Data have been accumulated and are now presented demonstrating the advantages of the centrifugal method, some of which are: (1) rapid establishment of equilibrium, (2) excellent precision yielding very reproducible results, (3) availability of high pressure differences between phases, (4) simple operational procedure, and (5) ability to establish connate water, residual oil, or to obtain complete capillary pressure curve in one day or less. A commercially available centrifuge capable of speeds up to 3,800 rpm, and a high speed attachment providing a maximum rate of rotation of 18,000 rpm were used in this work in conjunction with core holding tubes designed specifically for this application. In view of the outstanding advantages associated with the use of the centrifuge the conclusion has been drawn that this method should be used in place of the more tedious, slower, and less reliable disc method for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. INTRODUCTION The need for accurate values of connate water, residual oil, and capillary pressure curves in reservoir engineering has been recognized for many years, and the extent of the effort devoted toward solving these problems is reflected in the large number of papers3-" which have appeared in the literature during the past decade. Most of the methods discussed in the recent literature employ a porous disc as a semi-permeable membrane to separate two immiscible phases and make pos-ible the application of an explicit difference in pressure between two phases in the core. Thus, in the determination of the capillary pressure curve the wetting phase (water) is displaced by the non-wetting phase (air or oil). Several investigators1,2 have used centrifugal forces to develop pressure differences between phases. As a result of the first work' in this field the conclusion was reached that "the more rapid centrifugal method for measuring irreducible saturation may have equal value, (compared to use of discs) but more work is required to establish this point." This work was followed in 1945 by a more detailed study2 in which the concepts of this experimental work were more clearly enunciated. A method for calculating saturation for any given speed of rotation based on the observed volume of water displaced was developed and a wider application of the method was suggested. The absence of any subsequent pertinent literature on this subject is interpreted as indicating that no additional work has been completed to substantiate or deny the earlier claims and suggestions of promise contained in the original papers on this subject. One purpose of this report is to provide evidence designed to establish the practical value of centrifugal methods in determining core properties such as connate water and capillary pressure curves. It is also our purpose to suggest a broadening of the scope of this tool to include determinations of residual oil by gas or water drives. THEORY AND PRACTICE IN USE OF CENTRIFUGE Hassler and Brunner2 have clearly presented the basic concepts involved in the use of the centrifuge by relating the performance of a small core in a field of high acceleration to the

Jan 1, 1951

CRUSHING and concentration flow-sheets of western mills have become greatly simplified and more or less standardized of recent years with the introduction of modern grinding methods and flotation. Improvement has not stopped, however, and advancement is continually being made in crushing and milling practice. A case in point, where remarkable improvements in efficiency have resulted from comparatively minor changes in the flow-sheet, is in the New Cornelia mill of the Calumet and Arizona Mining Co. at Ajo, Ariz. This mill, completed in 1924 for the concentration ,of the sulfide ores of the New Cornelia mine, was originally designed for a 5000-ton capacity. Before recent changes and additions were made the five 1000-ton units were handling 6500 to 7000 tons per day, giving a flotation feed of approximately 14 per

Jan 1, 1930

By BION J. ARNOLD

WE can, I think, rightfully claim, irrespective of our faults, that engineers must, in order to last as engineers, possess the qualifications of integrity, stead- fastness of purpose, ability to think straight, and to apply these qualities consistently and continually in their everyday work. All engineers know this, most of them conform, and in order to drive it home I might, if 'clothed with proper authority, preach to you at length, but I shall not take the chance. So I only want to make a suggestion or two to the young engineers. Have an ideal and work toward it. You will have your disappointments and your temptations but keep your record clean, and if anyone says you are foolish or ugly, or homely, or that you need a guardian, take the criticism with a smile, for he may be able to prove his contention; but if he attacks your integrity, strike at once and fight hard, for he has assailed not only your character but your principal asset as an engineer.

Jan 1, 1929

By Emre Biringen

"Results from a small-scale laboratory experimental program show the changes in the vertical stiffness and strength of a soft clayey soil adjacent to the shaft of an inserted pile (i.e. expansion of a cylindrical cavity). The experimental program provides a realistic axi-symmetric physical model of an element of a cylindrical pile and the surrounding soil. The study interprets the improvement and assesses its magnitude in vertical stress-strain-strength properties of a normally consolidated soft cohesive soil in response to preloading impact in the radial direction. The results verify that insertion of a cylindrical pile causes densification of surrounding soil in a radial direction due to change in stress state around the pile, and thus consolidating and stiffening of the soil.The test results indicate that most improvement in modulus and strength takes place within a distance of 4 times the radius of a pile, though significant improvement is realized to a distance of 8-10 times the radius, beyond where there is negligible effect. Settlement characteristics of the surrounding soil in a zone of 12 times the pile radius improve significantly after the formation of a cylindrical cavity. The miniature vane shear strength tests show a 1.5 times increase in a zone of 4 times the pile radius compared to the strength at 10 pile radii. The results also imply that the spacing of cylindrical piles should not be more than 4 to 10 times pile radius, so that the surrounding soil matrix may improve the vertical bearing capacity under any foundation or embankment loading.INTRODUCTIONThe engineering community is familiar with different techniques to improve the bearing capacity and settlement characteristics of weak cohesive and organic soils. Some of the in situ techniques to improve the properties of soft ground (e.g. soft clays) prior to placement of foundations are vertical preloading, deep cemenUlime mixing, stone columns, and grouting (Henn 1996; Moseley 1993). In addition to these methods, researchers have recently showed interest in achieving soft ground improvement by means of applying radial compression method for which different names exist including expanding pile (Kelleher et al. 2001 ), Preload™ Pier (Biringen and Edil 2003), and sand compaction pile (Lee et al. 2004). Handy (2001) has described how preloading can also be achieved by imposition of radial loading in soft ground with an expected improvement in stiffness. The idea behind the latter method is densification and consolidation of soft soil in the radial direction by controlled displacement for which the process can be viewed as a cavity expansion problem (Vesic 1972)."

Jan 1, 2005