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By Bengt H. Fellenius

The bearing capacity equation?"the triple N formula"? is now about 50 years old. It was developed from theory of plastic resistance of metal to a cone being pressed into the surface of the metal, superpositioned by resistance due to shear in an interparticulate medium (soil; note, we are not dealing with metallurgy), and tempered by work necessary to move the footing into the medium. The equation (and its coefficients) was "confirmed" by tests on small footings placed at or near the surface of the soil. The equation is a basic tenet of every geotechnical textbook, manual, and code. Over the years, innumerable variations of the N-coefficients and adjustments to the equation have been published. The main assumption behind the bearing capacity equation is that a shear plane develops between two essentially otherwise unaffected bodies: the main soil body and a body comprised of the footing with some soil. Moreover, the notion is that a model footing placed at or near the surface of a soil would behave proportionally or similarly to a full-scale footing, or to even a same size footing (pile toe) placed at some depth in the ground. This is not in agreement with factual observations. It is suggested that the behavior of a small or large diameter footing as well as a pile toe is governed by compression of the soil below the footing or pile toe and not by "bearing capacity".

Jan 1, 1999

By F. Z. Suo

Baoahan Iron and Steel Complex is situated at lower beaches of the Yangtze River. The subsoils 50~70 M below the surface is a deposite of Yangtze River delta, consisting mainly of weak silty clay and loam, with low soil bearing capacity. Consequently, to build on such a weak soil a grant iron and steel integrated works weak soil improvement at the Complex, pile foundation is the effective type. It is estimated that at the first stage of Baoshan project 60,000 piles have been driven, of which 60% are steel pipe piles and 40% reinforced concrete piles. To provide reliable basis for pile foundation design, on-site loading tests were carried out for long reinforced concrete piles 27,45 60 M in length ,with strain gauges on the chief reinforcement of pile shaft and strain rod on pile tip. Based on loading tests, the paper discusses and analyses some issues, including determination of load transfer mechanism distribution of frictional resistance. Tests show that as far as long friction piles in soft clay are concerned, regardless of the properties of pile tip's bearing stratum, loads are mainly carried by shaft frictional resistance which it is effective to determine pile capacity in terms of P ~ S relationship.

Jan 1, 2010

By S. Kanai

Nodular piles is to be piles provided with several nodular projections along the pile shaft, as shown in Fig. 1. Nodular piles are usually installed through either driving method with hammer or preboring method. This paper presents that the bearing capacity installed through each method is considerably higher than that of cylindrical pile without nodules. This paper also proposes the statistically analyzed unique formulae of the bearing capacity of nodular piles.

Jan 1, 1989

By A. R. Naderian

Laboratory strength and deformation testing of freshly blasted sandstone and claystone overburden from Jeebropilly colliery in Queensland and in-situ plate-bearing tests on four backfills of different ages showed that the bearing capacity of backfill is a function mainly of compaction, not of age. The modulus or stiffness of the backfill is significantly increased by previous loading, in some cases up to threefold. Backfill material experiences some compaction through the passage of mining vehicles, likely to provide a bearing capacity that will support normal construction activities; the limited testing performed suggested that completed backfills are capable of supporting loads of up to 200 kN/m2 while sustaining displacements acceptable for a wide range of residential and industrial uses, but may be susceptible to collapse settlements due to saturation in the long term

Jun 19, 1905

By Z. Q. Zhou

It is the first worke in design of pile foundation to determine the carring capacity of single pile, and a static loading on site is considered to be the lost derect and reliable way. All values P and settlements S induced can be plotted as a broken-line. Since soil is a kind of elasto-plastic and cohesive material, the increasing of settlements is generally greater than that of loads. Different value Pu nay be given by different tester on his P-S diagram, because of erroys in the test and complicated, characteristics of soil. The analytical method of exponential equation shown in this paper derives a specified solution. After using an exponential curve to regress values of loads P and corresponding settlements S from on-site test, coeficients A and B of exponential equation can be obtained. With this curve an ultimate carrying capacity of single pile can be determined. The resistant forces of pile shaft and pile tip can also be defined by the tangent of the calculated knee point, as it is called (tangent method). At last, an example is given to show how the ultimate carrying capacity of f 500mm bored pile is obtained with this method for a project in Kunming.

Jan 1, 2010

By D. M. Milovic

On the basis of relatively large number of field load tests of piles, the determination of the ultimate bearing capacity have been studied. Using the load settlement curves and the results of the cone or standard penetrat­ion tests, the ultimate bearing capacity was determined by Van der Veen?s, Mazurkiewicz?s and bilinear approximation method. Also, the evaluation of the modulus of deformation and the unit skin friction has been discussed.

Jan 1, 2010

By M. J. Preim

Two case histories are presented on the evaluation of static bearing capacity of piles driven in soils that exhibit time dependent strength changes. Under consideration are a steel and a concrete pile driven into soils generally consisting of silty and clayey fine sand. Pile dynamic measurements and analyses were performed on both piles during initial installation, and also during restrike one week later. This information was used to predict each pile's long term capacity (defined as 14 days after initial drive), which was then compared to that measured with a static load test. Agreement between predicted and measured capacities were remarkably good, with an average error of only 4.5 percent. Two weeks after driving, total pile capacities were three times those at the end of drive. If only the skin friction was considered, however, it increased by an average factor of 16. The increase in pile capacity was determined to be linear over the time period considered.

Jan 1, 1989

By R. Bellotti

The theory of cavity expansion in an infinite frictional soil mass whose strength is represented by a curved Mohr-Coulomb failure envelope has been used to predict with some confidence the cone resistance of a clean dry sand. Experimental data were obtained from cone penetration and pressuremeter tests on two sands, conducted in a large calibration chamber (CC) under carefully controlled placement and boundary conditions. A plane strain bearing capacity theory was developed, and to convert the results to axi-symmetric conditions, an empirical "shape factor" was used. In the paper, the theoretical background, experimental data, calculation procedure, and the results of the analysis are presented. In general, a reasonable validation of the cavity expansion approach to the bearing capacity of deep foundations has been obtained.

Jan 1, 1987

By Miguel E. Ruiz, America L. Fernandez, Miguel A. Pandon

"Post-grouted drilled shafts (PGS) are a deep foundation system in which grout is injected at high pressure throughout the tip after the drilled shaft has been installed. Pressure grouting of drilled shaft tips can significantly increase the ultimate capacity and stiffness of drilled shafts. Conventionally constructed drilled shafts usually require higher axial deformation to develop the available side friction and the tip resistance simultaneously. They also tend to have higher tip compressibility and reduced end bearing capacity due to disturbance at the bottom of excavation during drilled shaft construction. PGS foundations have been found to be a cost-effective solution to compensate for this capacity reduction and/or compressibility increase. PGS construction procedure counterbalances tip compressibility and end-bearing capacity reduction. The tip grouting also has a pre-stressing effect over the shaft side friction since the drilled shaft tends to move upwards during the pressure grouting of the tip. After grouting, a bulb tends to form at the pile tip pre-compressing any disturbed material and, in certain cases, increasing the tip area, thus increasing shaft tip capacity.PGS load-settlement predictions using a load transfer approach are presented in this paper and compared with corresponding load test data. The paper also presents the main findings of load transfer analyses that were carried out to investigate the potential different factors that may be contributing to the observed improved performance of PGS over conventional drilled shafts. Results show that the two main factors, that may have a significant contribution on the overall performance of the foundation by increasing its ultimate capacity at any given level of settlement, are the stress-reversal of the skin friction and the formation of a grout bulb at the tip. The grout bulb tip contributes primarily through the increased tip area and to a lesser extent through increased stiffness and strength of the soil in the vicinity of the pile tip."

Jan 1, 2005

By Xu Youzai

Static loading teets of five nodular piles and four non-nodular piles were performed in Tianjin soft clayey soil in which measurements of axial force and movements were made. Distribution of shaft resistance and load-movment curves for pile head and pile toe are presented in this paper. The applicability of nodular piles to soft soil and their effectiveness are also discussed. Based on the comparison, it is concluded that nodular piles have an advantage over non-nodular piles mainly in contri­bution to shaft resistance. Dynamic testing was also conducted through R. P. T. for evaluating the service load of tested piles.

Jan 1, 1991

By Abolfazl Eslami, Samieh Rezazadeh

"Semi-Deep skirted foundations are considered to be a viable option for a variety of onshore and offshore applications. It is necessary to determine appropriate foundation configurations that allow loads to be transferred safely to the surrounding soil. For this purpose the bearing capacity and stability analyses subjected to combined vertical, horizontal and moment loadings must be found. In this paper the vertical undrained bearing capacity is estimated via finite element analyses. The circular skirted foundations with different geometries considering embedment depth (embedment ratio between 0-2) and size effects (diameter equals to 5, 10, and 20) have been studied. Stress field, kinematic mechanism accompanying failure and bearing capacity factors for total, end and shaft resistance in semi-deep foundations with various embedment ratios are investigated. Furthermore, two probable mechanisms i.e. internal flow and soil plug for estimating foundation capacity for design purpose in practice have been assessed. Comparisons with different research works including conventional methods, upper and lower bound approaches, and finite element analyses have indicated that the conventional methods underestimate the bearing capacity due to ignoring the significant role of shaft resistance. Determining appropriate economic foundation configurations to transfer loads safely to the surrounding soil is a major issue in geotechnical engineering. Shape and dimension of foundations, embedment depth, soil characteristics and applied loading, all affect the foundation performance. Recent studies have shown that for foundations with large breadth and of D/B between 1 to 4, kinematic mechanisms and failure modes are different from the two main types of foundation (i.e. shallow and deep). Therefore, D/B factor must not be considered as the only factor for defining foundation type. ""Semi-Deep foundations"" are another foundation category distinguished based on their performance. This relatively new concept is becoming increasingly an optimum alternative for shallow and deep foundations to support structures especially in accessible depth. As illustrated in ""Fig. 1"", different types of semi-deep foundations consist of:"

Jan 1, 2017

By Joseph Pogue

IT IS well known that one of the cornerstones of economic theory is the so-called law of supply and demand, which, really, is a group of economic laws, one of which may be succinctly stated : A rise in price tends, sooner or later, to increase supply. It is the fear that, in the case of petroleum, a limited natural resource, a point will soon be reached when supply will not respond adequately to price advances, which in recent years has prompted a movement for oil conservation. This movement has lately taken concrete shape in the appointment of a Federal Oil Conservation Board by the President. An important aspect of the law of supply and demand is that the supply of any commodity is not an entity per se, but is a factor of price. Supply, without the specification of price, has no exact meaning; and in practice supply cannot be divorced from considerations of price. Mathematically, supply may be expressed by the formula SP, which means that supply varies with price, just as the value of 10 raised to the x power varies with x. In its technical usage, supply is the quantity of a commodity that is bought currently on the market at a given price. In the case of a natural resource, however, this quantity will eventually depend not alone on price but on the physical volume of the reserve that exists and. that, in consequence, can respond to the stimulus of price. If this reserve is fixed in size, we must sooner or later reach a point where supply can no longer respond to price in the usual degree and a permanent shortage. will develop which no advance in price can correct, except in so far as higher prices may curtail demand or improve the efficiency of utilization.

Jan 3, 1925

By Joseph Pogue

IT is well known that one of the cornerstones of economic theory is the so-called law of supply and demand, which, really, is a group of economic laws, one of which may be succinctly stated A rise in price tends, sooner or later, to increase supply. It is the fear that, in the case of petroleum, a limited' natural resource, a point will soon be reached when supply will not respond adequately to price advances, which in recent years has prompted a movement for oil conservation. This movement has lately taken concrete shape in the appointment of 'a Federal Oil Conservation Board by the President. An important aspect of the law of supply and demand is that the supply of any commodity, is not an entity per se, but is a factor of price. Supply, without the specification of, price, has no exact meaning; and, in practice supply cannot be divorced from considerations of price. Mathematically, supply may be expressed by the formula SP, which means that supply varies with price, just as the value of 10 raised to the x power varies with x. In its technical usage, supply is the, quantity of a commodity that is bought currently on the market at a given price. In the case of a natural resource, however, this quantity will eventually depend not alone on price but on the physical volume of the reserve that exists and that, in consequence, can respond to the stimulus of price. If this reserve is fixed in size, we must sooner or later reach a point where supply can no longer respond to price in the usual degree and a permanent shortage will develop which no advance in price can correct, except in so far as higher prices may curtail demand or improve the efficiency of utilization. This statement brings us to the examination of amore fundamental aspect of the law of supply and demand as applied to natural resources; namely, that natural-resource reserves are not fixed in size: just as the current supply of a natural-resource commodity is a function of price, so its reserve is likewise a resultant of price. Natural-resource reserves; therefore, have no exact meaning without the specification of price, and in practice their measurement. cannot be divorced from considerations of

Jan 3, 1925

By E. S. Cheney

The sandstone-type uranium deposits of the Gas Hills occur in the arkosic, lower Eocene Wind River formation on the southern edge of the Wind River Basin. The d S34 values of pyrite cement associated with uranium mineralization are-significantly lighter than values for syngenetic-diagenetic pyrite nodules, therefore the H2S responsible for the precipitation of the epigenetic pyrite and uraninite was produced [t]epigenetically. These values are much lighter than the values of H2S from neighboring oil fields. The presence of biogenic pyrite in meta-igneous Precambrian cobbles indicates that these cobbles are not remnants of former; vein-type uranium deposits.

Jan 1, 1964

By William F. Boericke

CONSIDERABLE waste of oil and grease in lubricating motors and other machinery results from the use of bearings that are not totally enclosed. There is also the likelihood of damage to the bearing through the accidental introduction of grit or dust both in the oiling process and after, unless the cover is entirely dustproof. With the ordinary sleeve bearing that is only partly enclosed, it is generally easier for a careless attendant to cause trouble through neglect than with the ball bearing type, which from its design, must be totally enclosed to give effective service, and needs a minimum of attention. At one of the large mining companies which has taken a leading part in reducing unit costs and pioneering new developments in mining machinery, ball bearings have been gradually supplanting the conventional type of sleeve bearings on many of their motors, centrifugal pumps, and other machines in the mines. This innovation is not recent, as substitution of ball bearings on mine motors was first tried out by this company in 1909. Since then an increasing number of such bearings have been put in. They are now favored because of increased operating efficiency and reduction in lubrication costs.

Jan 1, 1926

By William Gleason

The Society for Mining Metallurgy and Exploration (SME) has a long and proud history of being the world?s leading resource for the dissemination for technical information regarding the fields of mining and mineral extraction and processing. That reputation was met, and maybe even exceeded, with the programming for the Society?s 2014 Annual Meeting in Salt Lake City, UT Feb. 23-26. The meeting drew more than 6,700 attendees to the three-day conference that featured more than 90 technical sessions with 670 presentations. These sessions covered the breadth of the mining and minerals industry, but it was the so-called ?softer issues? that were discussed in the keynote session that kicked off the meeting. The keynote session, ?Community Engagement: Building Partnerships for Mining,? brought together some of the leading voices from the mining industry, as well as some of the top voices from nongovernmental organizations (NGOs) that work in the mining sector. The common ground between the panelists was their dedication to working to ensure a social, economic and environmental balance in the development of mines. ?We wanted to bring these NGOs in to begin a dialogue to see how we can work together,? said SME President Jessica Kogel. ?This is a space that SME has not typically operated in, but one in which SME can bring a technical, scientific voice to the discussion. SME wants to play a leadership role in creating partnerships between the technical, social and economic areas that are crucial to the success of any mining project.? In today?s environment, finding mineral deposits and extracting the minerals in an economically viable manner is just one piece of an increasingly complex puzzle. Earning and maintaining a social license to operate requires careful consideration of local and global impacts. The industry often comes under intense scrutiny when a new project is proposed and, therefore, it must strive to meet the highest ethical and environmental standards. Success requires cooperation and collaboration between the industry, community and NGOs.

By David S. Dolan

To beat capital costs of US$10 per pound of installed capacity has appeared as a major hurdle for the "third generation laterite nickel plants. Forecast costs are escalating. Where can savings come from? Ore beneficiation can reduce the tonnage rate to be processed. High pressure acid leach options include the use of indirect slurry heating and higher operating temperatures to reduce flow rates and residence time. Progress has been reported in atmospheric leaching. High counter current decantation circuit settling rates and high underflow densities reduce CCD costs. Metal recovery options include direct from leach solution to metal production, as used by Bulong and espoused by Goro, and indirect recovery as used by Moa Bay, Murrin Murrin and Cawse. Plant location impacts on the costs of tailings disposal, power and energy costs, supply of consumables and labour costs, among others. Final nickel and cobalt metal production routes are electrowinning, hydrogen reduction or some innovative routes being proposed for Goro. This paper reviews the status in these developments, with particular reference to equipment and processes that offer lower capital costs. Keywords: Laterite, Nickel, Plant, Capital Cost

Jan 1, 2004

By Stanley Davidson

"This description of the structural geology of the Beattie mine has been condensed from a more comprehensive paper published previously (4).The property is in western Quebec, a short distance east of the Ontario boundary on the extension of the so-called Porcupine belt into Quebec.According to the geological surveys of the Dominion and Provincial Governments the regional structure in the vicinity of the mine is an easterly pitching, overturned syncline with several thousand feet of Timiskaming sediments in the centre surrounded by Keewatin volcanics (1, 2, 3).The mine lies on the north limb of the syncline, and the Keewatin series in this locality is, with few exceptions, overturned, dipping steeply north and facing south.The mineralization is closely related in space, and possibly genetically, to a body of syenite porphyry intruded into the Keewatin series along the north limb of the syncline. No ore has been found very far from the syenite or related lath-porphyry dykes, and the largest orebodies are composite, consisting of bleached and brecciated volcanics ( primarily tuffs) adjacent to altered syenite porphyry, both silicified and mineralized with very fine pyrite and arsenopyrite. In addition there are important ore shoots following a fracture zone within the syenite."

Jan 1, 1954

By C. T. Wallace

Evans Industries, Inc., a management coal consultant and company was assigned to evaluate National Steel Company's coal properties in Knott and Floyd Counties, Kentucky. The results of evaluation showed large reserves of good quality, high volatile metallurgical coal contained in the Elkhorn coal beds and resulted in the formation of Beaver Creek Consolidated Coal Company. Based on results of the exploration and feasibility work, the decision was to install a coal nine, preparation plant and related facilities having a production capacity of one' and three quarter million tons per year with Evans Industries acting as Beaver Creek's management company. The recoverable tonnage assigned to the Stinson Mine is approximately forty-five million tons. This paper discusses the general arrangement of storage, conveying, loading, refuse disposal facilities and the flow sheet of the preparation plant developed by engineers of Heyl & Patterson, Inc., and Evans Industries, Inc., with emphasis on practical flexibility, sulfur reduction in all circuits, and high product yield with the minimum amount of selective mining, Three and one-half miles of railroad have been built by the Chesepeake & Ohio Railroad to service this mine.

Jan 1, 1970

By O. S. Perry, D. F. Kidd

"BEAVERDELL IS IN the Interior Plateau of British Columbia, 25 miles east of Penticton, B.C. In 1897, small but rich silver-bearing veins were found on Wallace Mountain, 2 miles east of Beaverdell. Production from the camp, at first of a modest character, started in 1901 and has never ceased. Over 90 per cent of the values in the ores have been in silver. Remaining values present are in lead, gold, zinc, and cadmium.There have been four principal mines in the camp. A fifth is approaching production. The four mines lie within a northeasterly trending rectangle about 5,000 feet long and 2,000 feet wide, the fifth mine being at the northeast end. From southwest to northeast the mines, with their silver production to Sept. 30, l 955, are: -Wellington Mine - 1,463,948 oz.Sally Mine (includes Rob Roy claim) - 1,930,124 oz.Bell Mine - 3,460,815 oz.Lass Mine - 12,557,956 oz.Other production - 331,252 oz.Total, Beaverdell Camp - 19,744,095 oz.The camp is near the centre of an area geologically mapped in 19 l l by L. Reinecke for the Geological Survey of Canada (1). The rocks of the camp comprise:1. Beaverdell stock of porphyritic quartz monzonite;2. Westkettle batholith of quartz diorite;3. Wallace formation of tuffs and lavas.The Wallace formation borders the east edge of the camp, and has been intruded by the Westkettle batholith. The batholith is the host rock for the orebodies. The Wallace-batholith contact dips gently east. Some of the Beaverdell ores at depth, while in the batholith, are under Wallace formation mapped on the surface above.West of the camp, Reinecke mapped a stock one by one and one-half miles in size, of porphyritic quartz monzonite, which he considered much younger than the Westkettle quartz diorite (I). Recent petrographic work by White and Dolar-Mantuani (3) suggests that in the vicinity of the camp the Westkettle batholith is more quartz monzonite than quartz diorite, and little different in composition from the Beaverdell quartz monzonite. They suggest a consanguinity with the Westkettle batholith."

Jan 1, 1949