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By J. B. Morrow

WITH numerous plans under consideration for coal classification, and with the advent of the Bituminous Coal Code, the intelligent sam-pling of coal has become increasingly important. To us it is rather significant that there have been very few fundamental studies of coal sampling in American technical literature since those of E. G. Bailey, which appeared in the Journal of Industrial and Engineering Chemistry in March, 1909. He covered the subject up to that time so thoroughly and in such an excellent manner that perhaps many other later students have felt that they could add very little to his findings. The recent studies of the British Engineering Standards Association have indicated the possibility of a somewhat different interpretation of Bailey's results, permitting the taking of smaller samples, and perhaps it will now be helpful to reopen this question. C. W. H. Holmes, in an informative series of articles on coal sampling recently published in Colliery Engineering, makes two rather interesting statements, as follows: It is scarcely surprising to find a lack of interest and knowledge regarding the sampling of coal not only in the mining industry itself but also among consumers of industrial fuel: at its best coal sampling is a dirty business, regarded as a nuisance and an expense by the commercial man, and usually as a nuisance and nothing else by the chemist. The writer can conceive only two classes of people who have never experienced any difficulty in obtaining representative samples of coal from wagons; those who have never tried to, and those who have never had the necessity or desire to check the accuracy of their work. The primary purpose of this paper is to present some tabulated data of the more significant results of a sampling investigation undertaken during the last four years to obtain certain fundamental data on the variables connected with coal sampling and to point out that often assumptions have been made that are not in accordance with the facts. One of the standard sampling methods states:

Jan 1, 1935

By Arthur F. Colombo, David M. Hopstock

The Lake Superior region contains extensive deposits of potential iron ore in the form of fine-grained oxidized taconite. To help assure utilization of this resource in an environmentally sound manner, the U.S. Department of the Interior, Bureau of Mines, is conducting bench- and pilot-scale research using wet high-intensity magnetic (WHIM) separation. The advantages and disadvantages of WHIM separation in comparison with other feasible beneficiation methods are discussed. Pilot plant results are given for a flowsheet in which WHIM scavenging is used in conjunction with selective flocculation and flotation. A mathematical model for use in process optimization is given. Practical aspects of matrix selection and separator design for WHIM separation of fine particles are discussed.

Jan 1, 1980

By R. U. Jackson

FACED with rising costs, the mining industry is looking to new methods and equipment to supply the relief necessary for profitable operation. Conveyor transportation is rapidly taking a superior position to motor tramming in underground mines because of lower installation, maintenance, and operating costs. Haulage is always a critical problem in underground mining. The ease of operation and flexibility of a haulage system can have an important effect on ultimate mining cost. With the average tenor of ores on the downgrade, larger tonnages are required for the same metal recovery. This selection of a tramming system can be the key to a successful, paying plant. Because this shift is being made at an ever advancing rate, it may become necessary to tailor mining operations to the transportation system, rather than to select a haulage system fitting set mining methods. In choosing a haulage system, the relative costs of the various methods are of the greatest importance. Adapting the mine to one or the other type of tramming is not considered in the cost analysis, and very likely would make little difference, outside of location of drifts and raises. In the cost sheet, the problem presents recommendations for a conveyor installation and a comparison of equipment, installation, operation, maintenance, and power costs are made. Under the track haulage estimate, no allowance was made for dumping equipment at the shaft pocket or bin. If this equipment was added to the balance sheet, the additional

Jan 1, 1952

The Canada Centre for Mineral and Energy Technology (CANMET) /Calgary Coal Research Laboratory and the National Research Council in Ottawa established a joint working research group with industry to develop and test various computer models for application in surface coal mining operations in western Canada.The first part of the paper deals with the problems the group experienced during the past two years especially having model specification and requirements defined and understand site management practices.The second part of the paper deals with site specific development of general mine model for TransAlta Utilities' Highvale Mine in Alberta. Described here are the development of an interactive truck/shovel model for their three pit operation, selection and application of dragline model for tandem operation with the extended bench method, criteria for operational model of the five seams operation with selec-tive mining approach.

Jan 1, 1985

By P. R. Gage, R. W. Bartlett

At high temperatues and reduced oxygen pressuves, molybdenum silicicles oxidize to form SiO(g) vathev than a passivating SiO2 film. This is a sevious problem for low-pressure applications of sili-cide-coated rejvactory tnetals. As oxiclalion pvoceeds, the higher oxidntion potential of silicon initially suppresses oxidation of molybdenum and silicon is depleted near the surface. Eventually, silicon depletion causes secondary passivation (SiO2) mid an active to passiue transition in oxidntion behavior at moderately low pressures. At very low pressures, silicon depletion continues until steady-state oxidation of both silicon and rnolyhdenum can proceed at rates propovtional to their initial stoicliiorrzetvies. Ohsel-vations of 'oxidatiou-rate belzcriliov at temperatures from 1101° to 1700°C and oxygen pressures from 10-7 to 1 at in were made using thermogravimetn'c, X-ray diffraction, and elect?*on-rtric?ro/,vobe techniqrres. The experimental results are in good agreement with calculated lirnits for the various types of behavior that were based on tlievtnochernicnl atzd dffusion rate data for the Mo-Si system. A protective oxide film normally forms during the oxidation of elemental silicon. However, at elevated temperatures and reduced pressures this film is not present and oxidation is rapid. wagnerl has shown that this behavior occurs because SiO(g) is more stable than SiO2. The behavior of the silicides at high temperatures is similar but more complicated. Molybdenum and several silicide compounds are involved and the chemical activity of silicon, or the equivalent silicon vapor pressure, can vary considerably in these phases. Also, diffusion in the silicides resulting from reactions in which a higher silicide is reduced to a lower silicide, or molybdenum containing dissolved silicon, must be considered. EXPERIMENTAL AND ANALYTICAL METHODS Isothermal oxidation experiments were conducted using hot-pressed MoSi2 and Mo5Si3 wafers. Each experiment was conducted at a fixed oxygen pressure by controlling the flow of oxygen in and out of the furnace chamber. Most of the experiments were conducted in a molybdenum-wound tube furnace. Special construction features, including use of a high-purity dense A12O3 refractory tube, permitted operation in high vacuum to 1500°C. Higher temperatures could be obtained at higher working pressures and with a sacrifice of tube lifetime. Temperature was measured with three Pt 6 pct Rh/Pt 30 pct Rh thermocouples and controlled with a proportional controller. Weight changes were monitored with a quartz spring balance. The few experiments, at higher temperatures and low pressures, were conducted in a cold wall vacuum chamber using induction heating with direct susceptance of the sample. Because of the variable levitation effect of the induction coil on the sample, weight changes could not be monitored continuously in these experiments. All samples representing both experimental methods were weighed before and after oxidiation and examined with a microscope and analyzed by X-ray diffraction. The analytical treatment assumes equilibrium at interfaces and uses existing thermodynamic data. For convenience, equilibria are expressed as chemical potentials or as vapor pressures of the gases involved. The resulting differences in equilibrium vapor pressure between adjacent interfaces and between the surface and external atmosphere drive diffusion processes in the solid and gas boundary film, respectively. These diffusion processes govern the rate of oxidation. A bibliography of the sources of thermochemical data for the reactions pertinent to the Mo-Si-O system is given in Table I. Reactions are listed with the sources of free-energy data referenced. Since all of these reactions involve one or more gas species, usually oxygen, a plot of the product-gas chemical potential, -RT In Pg, vs absolute temperature for each reaction is given in Fig. 1. These curves can be used to determine equilibrium vapor pressures or to compare the stability of different compounds in the various gases: O2, Si, SiO, and Moo3,. The data of Table I and Fig. 1 were used to determine the analytical results presented in this paper. EXPERIMENTAL RESULTS The weight changes for three MoSi, samples oxidized at 1500°C are plotted against time in Fig. 2. The treatments were identical except for the indicated variance of oxygen pressure and each curve represents one of three characteristic types of behavior that were observed. The upper curve is an example of passive oxidation, which is defined as

Jan 1, 1965

NORTH AMERICA Number Members Alaska 31 Canada 302 Mexico 175 Newfoundland 3 United States Alabama 52 Arizona 131 Arkansas 9 California 723 Colorado 184 Connecticut 98 Delaware 19 District of Columbia 133 Florida 16 Georgia 6 Idaho 61 Illinois 241 Indiana 57 Iowa 7 Kansas 32 Kentucky 33

Jan 1, 1932

By Dwight K. Smith, Greg Carter

Studies have been conducted on The properties of many deep well cementing compositions to determine their Strength behavior over curing periods to 180 days at elevated tem-peratures and 3,000 psi pressure. This pressure results in essentially the .vat, compressive strength as that obtained with much higher pressures in ac-cordance with the findings of an API subcommittee ' These different compositions include API C1asses A, E, and F cements containig additives such as retarders, berrtorlite, heavy weight materials and pozzolans. All compositions except mixtures of Poz-zolrrrts and hydrated lime show from mild to severe degrees of strength lass over a temperature rang from -730 to 320" F after setting. Pozzolatl-time compositions actually gain in strength with time at these high temperatures. Other chemical find physical properties evaluated to observe their inter-relation.ship with Strength loss show very little correlation except in per-meability. As retrogression in strength increases, the permeability of set cement increases. X-ray difraction patterns on the set products indicate the formation of certain compounds having little or no strength value in those cementing compositions where strength loss was more severe. INTRODUCTION As a result of the growing trend toward deep well completions, a study has been made on the properties of the various cementing slurries presently in use at elevated temperatures and pressure. The strength of these compositions is of prime importance in selecting the most suitable material for use at high temperatures, to determine WOC time and the proper time to perforate with a minimum of shattering. Of primary interest in this investigation was the strength behavior of various compositions currently in use, and the effect of additives on cement after long periods of curing under severe conditions. Earlier investigators have pointed out that the strength of some cements will increase with increasing curing temperature to about 220 to 340" F, but at higher temperatures a loss in strength occurs at extended time intervals. Studies by the API Mid-Continent District Study Committee on Oil Well Cements' outlined a testing procedure whereby field conditions of temperature and pressure could be simulated in the laboratory.' It was observed that retarded cements undergo changes at elevated temperatures and some lose as much as 50 per cent of their early strength when cured at high temperatures. The scope of these tests was limited to curing periods of 1 to 28 days; additives were not covered in this study. Saunders and Walker' found that the use of additives influenced the strength behavior of cements at high temperatures, but studies were conducted only to a seven-day curing period. Ludwig and Pence' conducted an investigation of two types of cements under elevated pressures and temperatures in an effort to explain the causes of this loss in strength phenomenon. It was observed that with retrogression in strength there were other physical and chemical changes which took place as the cement aged. Today there are a number of cementing compositions available for use at well depths below 10,000 ft. Since all these earlier investigations were limited in curing time as well as the number and type of compositions studied, it was believed that a more extensive study should be conducted on the properties of cements at elevated temperatures, and this work should include those compositions actually in general field use at this time.

of our good friends and fellow members: William D. Brennan Charles Beuchat who left the world better for their having lived in it.

Jan 1, 1931

By R. F. Shurtz

The author proposes a method used with some success on a magnesite deposit at Gabbs, Nev. He believes this procedure to be more sound than the blind practice of assigning uniform quality to large, soinetimes vast blocks or ore on the basis of analyses made of a small number of samples. When an ore deposit is evaluated on the basis of core sampling, questions always arise as to how much weight should be given the various sample grades and how the deposit should be divided into specific volumes assigned to corresponding grades. For a tabular deposit it is customary to use the so-called zone-of-influence. This zone is usually defined as the polygon in the plane of the deposit having corners halfway between a given core drill intersection and each of the nearest neighboring intersections. The volume of the ore in this polygon is assigned the analysis obtained from the drill core taken at the intersection. In massive or irregular deposits, volumes of various shapes may be defined with respect to the locations of drill core samples. These volumes may be regarded as three-dimensional zones-of-influence; the theory involved in assigning the values of the central analyses to the ore in the volumes is the same as that used in the case of a tabular deposit. The zone-of-influence method was used in evaluating one of the magnesite deposits at Gabbs, Nev.'-"

Jan 1, 1960

Jan 1, 1892

By Cyril Smith

ALTHOUGH not of the same importance as electrical conductivity, the capacity for conducting heat is nevertheless a very important property of metals and alloys. A knowledge of thermal conductivity is of value in selecting alloys for many purposes and in the calculation of the efficiency of apparatus which is being designed. Unfortunately, the determination of thermal conductivity is extremely slow and tedious, consequently few data have been obtained. A further reason for the lack of information is that there has long been an impression that the thermal conductivity of an alloy is directly proportional to the electrical conductivity and that it can therefore be calculated from the latter. The Wiedemann-Franz-Lorenz law of constant ratio of the two conductivities holds with a considerable degree of precision for all the pure metals, but appreciable deviations occur in certain alloys-particularly those containing nickel-and it seems difficult to predict exactly what the ratio will be. Therefore direct determinations of thermal conductivity should be made whenever the results are, needed with any accuracy. This research is intended eventually to cover all the alloys of copper that are of commercial importance, including the binary alloys of copper with zinc, tin, aluminum, nickel, silicon, manganese, cadmium and phosphorus, and the ternary alloys copper-nickel-zinc, copper-nickel-silicon, copper-manganese-silicon, copper-zinc-tin, etc. Most of these alloys are customarily used in the wrought condition and therefore were tested in the form of annealed rods. A limited number of sand castings were also obtained and examined. This paper contains a complete review of all the previous work that has been done on copper alloys, and includes a detailed description of the apparatus and method of procedure used in the present research, together with the new results obtained on the copper-zinc series, which is the only one completed at the present time. Subsequent papers describing the other alloys will contain the experimental results and discussion only.

Jan 1, 1930

By Martin Hertzberg

The concept of limit burning velocities is being used to formulate a quantitative theory of flammability limits. Competing and complicating processes dissipate power from a combustion wave and quench propagation at some characteristically low limit velocity. Two earlier reports dealt with process (a), natural convection (RI 8127); and with process (b), conductive-convective wall losses (RI 8469). This report considers process (c), radiative losses, and process (d), selective diffusional demixing. The limit burning velocity for radiative losses is [(SU)c ~ e cp] It is normally not a significant process for premixed gas flames; however, for laminar flame propagation in a gravity-free environment, it is the only loss process present. Accordingly, limit velocities at zero gravity should be much lower than on earth, and premixed gases should be flammable over wider composition ranges. For highly emissive dusts, soot, or ash-forming flames, radiative losses are significant even under normal gravity conditions. Selective diffusional demixing is a complication that manifests itself in the form of cellular flame structures and wide gaps in composition between upward and downward propagation limits. It induces a burning velocity shift (?Su)d, causing the flame to behave as though it were richer or leaner than its initial composition, depending on whether the fuel or the oxidizer mole¬cule has the higher diffusivity. A simple pertubation analysis shows that the process generates stable cellular flames whenever [dsu] > 0, where ci is the concentration of the reactant with the higher diffusivity. The same analysis indicates that at the opposite stoichiometry, where [dcu] < 0, laminar structures are stabilized. A simple formula for the diameter of cellular flames is derived, which predicts that dcell should vary inversely with the product of the diffusivity difference Di -DJ, and the burning velocity slope [dc ]. Those predictions are in good agreement with the available data. Buoyancy forces for upward propagation induce flame front curvature, and hence buoyancy and selective diffusion are mutually supportive in upward propagation. Thus large gaps in composition between upward and downward limits are present in those composition domains where cellular flames are stable.

Jan 1, 1981

By Luciano B. Oliveira, Angela O. Costa, Sergio N. Monteiro, Luis Guilherme C. Marques

"Biofuels are gaining a relevant role in today’s world not only as a solution for the decreasing petroleum reserves but mainly as a positive contribution to the efforts in global warming mitigation. In Brazil, since 1975, the replacement of gasoline by ethanol started a so-called PROALCHOOOL program, which is now being complemented with the replacement of petroleum diesel by biodiesel. This biodiesel program was officially created in 2005 with mandatory goals, supported by legislation, of 2% addition in 2008 and 5% addition in 2013 into all commercialized regular diesel. In this work, a critical analysis of the Brazilian biodiesel program is presented. The technical aspects related to the different raw materials, including wastes, available for biodiesel conversion as well as the economical conditions associated with production costs and market logistic are discussed. The environmental benefits associated with the retention of greenhouse gases are also discussed.IntroductionToday the commonly accepted fact that the petroleum world reserves are probably passing through a maximum and start declining in terms of the total amount that can be extracted by existing technologies is motivating significant changes in our society. The continuous increase in the price of gasoline and other liquid fuels is an immediate worrisome and visible consequence. However, more than an economical problem, our civilization is already facing the effects of global warming, due to CO2 emission from burning fossil fuels, mainly from coal and petroleum. It is now realized that a large scale solution for these problems demands the prompt substitution of non-renewable fossil fuels by others that, in addition of being renewable, have a relatively lower contribution to the greenhouse gases."

Jan 1, 2008

By Nicholas J. Grant, John Chipman

A FULL understanding of the behavior of sulphur in the basic open-hearth process has been delayed by lack of dependable data covering a wide range of slag conditions in the absence of other complicating factors that are likely to be present under operating conditions. It has been generally accepted that strongly basic slags will dissolve more sulphur than will those in which the acidic and basic constituents are more nearly balanced. It has been known that both slag and metal would absorb sulphur from the flame when the sulphur content of the fuel is high. It has been generally believed that manganese assists in the transfer of sulphur from metal to slag. Almost nothing has been known of the effect of temperature upon desulphurization; the data have been conflicting and there has been a tendency to depend rather heavily upon analogy with the better understood desulphurizing reaction of the blast furnace. Many attempts have been made to build up from open-hearth data a satisfactory theory of the chemical reactions involved in the process. That this has been an extremely difficult task is owing to two reasons that have been very generally recognized. The first is the parallel and simultaneous reaction of sulphur transfer between flame and bath. The second is the difficulty of distinguishing between the factors that ultimately limit the transfer from metal to slag-i.e., equilibrium conditions-and those whose influence is only upon the rate of transfer. It has been the object of the work here recounted to study the equilibrium distribution of sulphur between slag and metal in the absence of these complicating factors, with the hope that a better understanding of the equilibria involved would lead to a better control of the over-all process in the open-hearth furnace. A review of the literature on steelmaking reveals almost complete agreement with respect to the paramount importance of lime in promoting desulphurization. In expressing this effect in quantitative terms, however, and in formulating the relationships between the concentrations of other slag components and the desulphurizing power, there is little agreement. For instance, the "basicity" or basic strength of the slag is commonly measured by some kind of ratio of concentration of basic to acidic oxides. Of these, the following have been reviewed by Schenck :20 [ ] Among others there appear the following:

Jan 1, 1946

By Erik Olsson, Gunilla Hyllander, Stefan Schuster, Lena Sundqvist Ökvist, Maria Lundgren, Michael Hensmann, Olavi Antila

"Residual materials from the integrated steel plant itself or other sources often contain valuable compounds of e.g. C and Fe. Dust and sludge have to be agglomerated to be able to recycle to the blast furnace (BF) via top-charging. By injection of the materials, preparation methods in terms of e.g. drying and/or screening only, can be used. Alternative carbon materials (ACM) in terms of BF dust and sludge have been successfully injected up to levels of 60 kg/tHM in the LK.AB Experimental Blast Furnace (LKAB EBF®). Efficiency in recovery of valuable compounds as well as the behavior of undesired elements have been evaluated and are discussed.IntroductionTraditionally, recycling of steel in-plant fines is made via the sinter plant and blast furnace route. Steel plants operating with 100% pellet as ferrous burden and have no sinter plant. There are limited areas for land fill and costs are caused for preparation of landfills and deposit fees. Very fine paniculate dusts or sludges cause decreased productivity and increased coke rate in the sinter plant, and therefore other ways for recycling must be considered. Injecting them into the BF could be an economically and technically feasible alternative. Additionally, as the materials contain valuable compounds of e.g. C and Fe."

Jan 1, 2012

By John F. Papp

The Bureau of Mines has sampled microstructure of low-pressure flat flames by mass spectrometer for normal methane-oxygen-argon and for methane-oxygen-argon-bromotrifluoromethane flames. The physical and chemical phenomena, and the method of analysis of mole fraction data to evaluate net reaction rates are here considered in detail. Included is a computer program listing with output on one flame. Chemical species considered are CH4 , CO, CO2, H, H20, OH, Ar, H2, O2 , O, H2CO, CH3 , CF3Br, HF, HBr, Br, CH3Br, HCO, F2CO, CH2 CF2 , H02.

Jan 1, 1975

By Sengstock G. W, Spathis A. T

Benchmarks of mine equipment involved in the excavation process of coal mines would suggest that such equipment is not always operating at an optimum level. Dragline operations and truck/shovel operations rely on efficient use of their plant in order to maintain high mine throughput. The first process which affects the material to be excavated is the drilling and blasting process. Drilling and blasting delivers a fragmented material with a given disposition ready for excavation by mine equipment. As mine operators demand more productivity from their major excavating equipment, many sites are considering the use of productivity monitors to measure their outputs. Some of these productivity improvements will be directly related to the drilling and blasting process, so that as the monitoring systems improve, the opportunities to evaluate all drilling and blasting variables will also improve. This paper reviews current and newer methods for monitoring equipment productivity in mines. These include simple time and motion studies obtained by either manual timing of processes or by automated data collection equipment being adopted by the industry. Case studies for truck/shovel operations are discussed and the productivity improvements are compared with typical industry standards. These improvements relate specifically to parts of the load, haul and dump cycle and the potential for significant improvements are identified. Particular opportunities for drilling and blasting improvements are also presented.

Jan 1, 1995

By Van Dyne Howbert, Fred E. Gray

The Presidio mine of The American Metal Co. of Texas is situated 45 miles south of Marfa, Texas, a town on the Southern Pacific R. R., and lies approximately 20 miles north of the Mexican border. Communication with the railroad is maintained over a state highway. All supplies for mine and mill are hauled in by truck from Marfa and precipitates and concentrates are freighted to the railroad by the same means and shipped to Selby and El Paso, respectively. The mill is at the town of Shafter, 1 mile from the mine and at approximately 350 ft. lower elevation. The ore is conveyed to it by an aerial tramway which requires practically no power on account of the difference in elevation. The mill is a countercurrent decantation cyanide and gravity concentrating plant of 200 tons daily capacity. Coarse and fine crushing are done at the mill. Two neal-by shallow wells in the bed of Cibolo Creek furnish an abundance of water. Power is generated for the mill and town by a Diesel engine plant. Ore Treated The ore is oxidized and siliceous. The greater part contains approximately 16 oz. of silver per ton, but mixed with this are many particles of ore of much higher grade, assaying in many instances 100 oz. or more. In the 16-oz. material there is an almost constant amount of silver which is difficult to recover by cyanidation. The high-grade material contains a much greater proportion of silver which is easily amenable to cyanide treatment. Thus, as the grade of ore becomes higher, the percentage of recovery of silver increases rapidly, under equal milling conditions. The silver minerals contained in the ore are principally argentite and cerargyrite, the former predominating The lead minerals, all of which are argentiferous, are chiefly cerussite and galena, with occasionally a little anglesite. The gold is free; most of the ore contains merely a trace

Jan 1, 1935

[Note.—The paper of Mr. Hoffman on " Practical Results in the Magnetic Concentration of Iron-Ore " (page 602); that of Mr. Langdon on "The Use of Magnetic Concentrates in the Port Henry Blast-Furnaaces" (page 599); and those of Mr. Landis on "The Determination of Iron in the Tails from Magnetic Concentration " (page 609) and "Note on Sampling Iron-Ore" (page 611), were all prepared as contributions to this discussion.] The papers of Mr. Langdon and Mr. Hoffman were presented. W. H. Hoffman, Croton Mines, N. Y.: I will add a few remarks, by way of answer to inquiries for further details. The Croton Mines are particularly well located for cheap mining. The ore-bed is very large, and so lies in relation to the railway tracks of the Harlem and other railroads that a very large proportion of our mining for several years to come can be done above these tracks. The concentrating-mill is now 400 feet from where we are working in the quarry. In blasting we never remove less than 2500 tons at a blast,

Jan 1, 1892

By G. Ranjan

The designers and the practicing engineers have started using latest and cost effective techniques of ground improvements which utilise the weak and poor sub-soil deposits efficiently for the civil engineering construction. In the present investigation, a new concept of &apos;skirted granular piles&apos; has been advocated. An effective method of construction of granular piles as an economical alternative to vibroflot, and the skirt has been developed. The construction technique is based on indigeneous know how which effectively utilises the man-power technology avoiding import of costly equipment suiting to the developing countries. Full scale insitu tests have been carried out at four sites, having different soil conditions, on virgin weak sub-soil, and improved ground by casting plain and skirted granular piles. Effectiveness of different types of skirt has been demonstrated through insitu tests. A simple analytical approach has been proposed to predict the ultimate pile capacity. The predicted values of ultimate capacity have been found to demonstrate a good correspondance. Granular pile behaviour in terms of pile depth, diameter, spacing and stress deformation characteristics of the improved ground have been discussed. A significant improvement in ultimate capacity in improved ground has been noted. This is further augmented when granular pile group is skirted.

Jan 1, 2010