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A. R. Ledoux,New York City: The so-called combination method " is generally used in assaying bar copper for silver. It has been modified from time to time. Briefly outlined

Jan 1, 1901

H. Van F. Furman, Denver, Colo. (communication to the Secretary): There are some statements in Dr. Carpenter's interesting paper which appear to require explanation, if not modification.

Jan 1, 1901

George L. Heath, South Lake Linden, Mich. (communication to the Secretary): In presenting some notes on the "Heine's Blue Test" Mr. Smith expresses a preference for fresh standards and a cheaper bottle; but this is rather a reversion to the old method, since I devised in 1897 the newer method of preparation and preservation of' permanent standards, which were not used with any success in the original method. Many busy western assayers no doubt value a method for preparing a permanent set of standards in air-tight glass-stoppered bottles, whose use brings the method as near perfection as one could desire as regards rapidity of color-reading and avoidance of unnecessary work. Mr. Smith notes that his color-readings were compared with an electrolytic assay of another ore-sample, and that my electrolytic assays were made on the " blue test" solution from colorimetric assay. He omits, however, reference to the fact, showing the advantage of my procedure, that the next column in table of

Jan 1, 1901

By E. A. H. Tays

At the present time, the mine-owner has a number of patent crushers to choose from, when contemplating the erection of a mill; and a number of new ones are yearly brought to notice. We all know that the stamp-mill is the old standard; but several of the patent crushers, especially of the roller-type, are not without their merits. Having had a working experience, extending over a period of four years, with the " Bryan roller quartz-mill," working alongside of stamp-batteries, I take pleasure in giving to the members of the Institute the benefit of my experience with this mill.*

Jan 1, 1900

By Charles Kirchhoff

For twenty years it has been my work to watch and record progress in both the technical and the commercial branches of mining engineering in the wide sense in which it is represented by our Institute. While you who have been actively engaged in our profession have made history, a few of us have attempted to be the historians and have been kept keenly on the qui vive to follow the developments of so broad a field. One so employed may be pardoned if he ask you to pause for the unusual purpose of looking backward, that you may measure what you and others have done, and that the younger men may gather inspiration from the work accomplished by their elders and their predecessors. It is not so long since that the commercial management dominated our industries. Bred in the school of science, which seeks its reward in establishing the truth, our engineers were sometimes indifferent to trade conditions and requirements. Much of that feeling has disappeared, and the engineer recognizes that it is his mission to apply the achievements of science to a useful commercial end. On the other hand, business men now understand that the utilization of our natural resources and the production of articles for consumption is impossible without the intervention of the engineer. They must co-operate, unless, indeed, the two functions are combined in one man —a rare but powerful combination. Now the final measure of success of both is the cost sheet on the one hand and the expansion of markets on the other, so closely interwoven, so mutually interdependent. There is one cardinal feature, however, which characterizes the engineer's work—namely, the permanence of his achievements. Every improvement, particularly when it has been recorded in such lasting form as a paper in the Transactions of our societies—

Jan 1, 1900

By H G. Poulos

"This paper sets out a simplified approach by which the practical foundation designer can undertake the relevant calculations to satisfy the requirements for deep foundation design in seismic areas. The following matters are dealt with:a. Design issues that should be addressed;b. Pile design for axial loading, including the possible effects of liquefaction;c. Pile design for lateral loading where liquefaction does not occur;d. Pile design for lateral loading where liquefaction does occur;e. Measures to mitigate against liquefaction effects.The paper is a modified version of a paper presented in 2013 to the 19th NZGS GeotechnicalSymposium, Queenstown, New Zealand.1. INTRODUCTIONConsideration of the effects of earthquakes and seismic loadings is an increasingly important aspect of modern foundation design, and most contemporary standards have a mandatory requirement for such consideration. For example, the Australian Piling Code, AS 2159-2009, states that “a pile shall be designed for adequate strength, stiffness and ductility under load combinations including earthquake design actions”. However, the methods by which such considerations can be undertaken are generally not set out in the standards, and many approaches have been utilized, ranging from very simplistic methods to extremely complex computer analyses. Accordingly, there appears to be scope for an approach that is soundly based but which is neither too simplistic nor too complex.Poulos (1989) has suggested that there are three categories of analysis and design, as follows:1. Category 1: empirical methods.2. Category 2: simplified but soundly-based methods.3. Category 3: more comprehensive methods that are soundly-based, and site-specific.The objective of this paper is to set out a systematic but simplified approach which falls into Category 2 above, and by which the foundation designer can undertake the relevant analyses to satisfy the foundation design requirements for seismic regions. Emphasis is placed on methods that do not require “black box” software or which employ complex soil models in which the physical meaning of the parameters is unclear."

Jan 1, 1900

By Ernest R. Woakes

Cana, originally called Santa Cruz de Cana, is situated in the province of Darien, in the Republic of Colombia, S. A. The river Cana is a tributary of the Tuyra, which flows into the Gulf of San Miguel, and thence into the Pacific Ocean some 80 rniles S.E. of the City of Panama. • The Espiritu Santo mine lies on the S. side of the Cana river at the foot of the Espiritu Santo range. The plateau of Cana has an elevation of 2000 feet above sea-level, and the mine is about 200 feet above the plateau. The map of the Darien accompanying this paper is the only correct one in existence. It was made by Lucien N. Bonaparte Wyse for the Panama Canal Co., and has been copied fur the present use, with permission, by Mr. L. G. Inglis. The dotted line on this map shows the route from the coast to Cana. As this mine was one of the most celebrated at the time of the Spanish occupation, it is only natural that there are a great many traditions and writings concerning its former workers and production. Dampier mentions it, though he does not seem to have been nearer to it than El Real de Santa Maria, the port on the Rio Tuyra, about 50 miles by road from Cana. Senor Vicente Restrepo's work, entitled Estudio sobre las Minas de Oro y Plata de Colombia, translated by C. TV. Fisher and published in New York in 1886, is, perhaps, the best treatise on Colombian mines. He has devoted a great deal of attention to the subject of the Espiritu Santo mine, and has had access to all that dealt with it in the archives of Bogota. It will be interesting to quote a few pasaages from the above work, which seemed like a romance to the writer of this paper some years ago, when he first came across the history. Being actually in Cana at the time, and knowing the present company had

Jan 1, 1900

By D. P. Mitchell

Western Australia is the home of much that is new and interesting in the gold-mining industry. Some of the gold deposits are outranked for size and value by nothing yet discorered, while the value of the ores is, in many cases, rivaled only by their complex character. As in all parts of the world, many of the ore-bodies occur in ways which tax the skill of the miner in following them; and among these the writer considers the case of the East Murchison United more interesting than the average. This is one of the leading gold-mines of the colony in point of production, and is situated near the town of Lawlers, in the East Murchison district. The country for several miles around the mine is mainly granite, and the line of outcrop on which this mine is located can be traced for a long distance. As will be seen from the accompanying plan (Fig. I), there are, at the water-level, two nearly parallel veins running slightly north of west. Structural Features.—The most striking peculiarity of these veins, and the hardest to understand, is their tendency to send out horizontal stringers or side-veins. These vary in size from a veinlet an inch thick to a veil] several feet in width, and they extend with great persistence into the wall-rock on either side of the vein. This tendency is shown in Figs. 2 and 3. The usual signs of a movement of the wall-rocks, such as a ribbon-structure of the quartz and a well-defined gouge or seam of clay along the walls, are in many places lacking, while in other places they appear strongly marked. They seem more in evidence below water-level than above. It is a commonlly accepted idea that when a gold-bearing vein loses in width, it often gains in value. In this instance, however, the direct opposite is the case; for in many stopes it has been possible to leave the narrow portions of the vein to act as pillars, and to extract only the wide portions, which are

Jan 1, 1900

By Charles Catlett

Some years ago the writer was struck by what might be called the remarkable vitality of the Virginia furnaces during the panic of 1893; and attention was called to the fact in the American Manufacturer of February 8,1895. From the second half of 1892, which was a period of maximum output, to the second half of 1893, when the full effects of the depression had been reached, the output of pig-iron had fallen off in Illinois 85; in New York, 66; in Ohio, 51; in Tennessee, 44; in Pennsylvania, 28; and in Virginia only 15 per cent. It seemed a reasonable inference that the State which had thus shown its marked ability to meet hard times could make and market its product with a larger margin of profit than any of the other States. This was true at that time, and to a certain extent the reasoning still holds good; but my mistake was in not fully realizing the marked effect of the Mesabi development, combined with reduced economies in transportation, and the consequent advantage to those furnaces which were so situated as to utilize these new commercial factors. The effect of these factors is seen in comparing the second half of 1894 with the second half of 1892. New York had dropped off 44, Alabama 23, Tennessee 21, Illinois 19, and Virginia 16 per cent., while Pennsylvania had increased 5 and Ohio 10 per cent. While there is no question of the great economy which has been made possible for certain interests which are peculiarly situated with reference to the ores of the Northwest, it is yet too early to say what furnaces not so fortunate will have to pay for their raw material. Already an increase of twenty cents per ton of ore has been announced, based upon increased cost of production.

Jan 1, 1900

By C. M. Haberfield

"1 INTRODUCTION Around the world, there is a demand for larger structures, tall buildings and large bridges. While good footing design is important for all structures, it is even more important in the case of large structures. Recent experience with footing design for tall buildings (e.g. Burj Al Alam development and Nakheel Tower in Dubai, the Gate of Kuwait in Kuwait, the City Centre Project in Bahrain and Eureka Tower and Freshwater Place in Melbourne) has shown the benefits of investing in footing planning, design and construction (Haberfield, 2011, Poulos and Bunce, 2007). The footing systems for most of these projects include the use of deep bored piles or barrettes (piles of rectangular cross-section). Many use piled rafts where the piles, while acting to support the load, are primarily used to reduce settlements. A clear understanding of the factors controlling the behaviour of the footing system is needed to enable a good engineering design to be achieved. This starts with a sound understanding of the ground characteristics and individual pile performance, including adequate collection of data and testing. The best footing solution can then be found using recent improvements in data collection and analytical techniques, complex and highly capable computer-based models and the availability of high speed computers. This paper focuses on the axial performance of deep bored piles socketed into rock – both their individual performance and their performance as part of a larger footing system. Recent research and construction practice is discussed. In practically all cases, serviceability conditions control the behaviour of the footings. Methods of establishing the parameters for input into sophisticated computer programs are described. Application of the methods to case studies is included and it is shown that the behaviour of individual piles can be closely predicted. These developments lead to lower construction costs, better constructability and shortened construction time because of the better understanding of footing behaviour. 2 FACTORS AFFECTING PERFORMANCE OF FOOTINGS ON ROCK For a typical pile-supported footing, it is necessary to consider both individual pile, pile group and raft performance. These require consideration of the behaviour of the ground immediately beneath the surface raft or footing, along the pile shaft, and at and beneath the pile toe (Figure 1). Immediately beneath the surface raft or footing, the important factors are strength for bearing capacity and stiffness for settlement and interaction effects. Along the pile shaft, of most interest are strength for bearing, excavatability and stability; stiffness for settlement and interaction effects; geology and permeability for pile stability and, most importantly, pile shaft resistance. At the pile toe all the above factors for the pile shaft are present and in addition the pile end bearing is of interest. Below the toe, stiffness for pile settlement is important to at least a depth of twice the building width."

Jan 1, 1900

By Erwin S. Sperry

Some time ago, the author had occasion to make an alloy of equal parts of nickel and aluminum, for the purpose of adding small amounts of nickel to pure aluminum. The nickel was melted in a plumbago crucible under a layer of borax ; and at a proper temperature the aluminum was added, and the whole mass was stirred with a plumbago stirrer. The alloy immediately became incandescent and boiled. It was then poured into iron moulds, in the form of ingots weighing about 10 pounds. The metal when poured was very fluid and free from the viscosity so often noticed in nickel and nickel-alloys. The color of the alloy is gray, not unlike that of wrought-iron, and the fracture is devoid of any crystalline appearance. It is quite brittle, and can be readily ground to a powder in a mortar. More metal was made than was needed; and what remained unused was placed in a covered wooden box and set away. In about three months, as it mas again necessary to use the alloy, the box was opened; and, much to my surprise, nothing but a dark gray powder was found in it. This condition of the alloy could not be accounted for. An attempt was made to melt the powder and pour it again into ingots, but with negative results. Analogy pointed to disintegration; and it was decided to make a fresh sample of the alloy, and watch the material from the beginning. In the second experiment the conditions were identical with those of the first, with the exception that fluor spar was substituted for the borax. This change was made because it was thought that perhaps the borax might have been

Jan 1, 1900

By B. L. Thane

Within the past few years, the mining industry has taken a new impetus in all its branches. New mines are being opened every day, while old ones, which have been either working at a loss, or have been compelled to shut down, are now gradually being reopened and placed on a paying basis. This growth and new life is due, in a measure, to the discovery of new mining districts, but the most important cause of the progress is the wonderful advance that has been made in all branches of mine-engineering. By means of the important inventions and discoveries that have been made in mechanics, chemistry, and electricity, we are now able to work ores which, only a short time ago, would have been regarded as worthless. We find, for instance, the electrician eliminating two of our greatest difficulties, those of distance and superior elevation, while the mechanic has brought to the highest degree of perfection, not only ore-crushing and hoisting machinery, but all such devices as pertain to the mechanical handling of ores, and, at the same time, the metallurgist, with his combined chemical and mechanical skill, has helped us to extract the precious metals from the most refractory of ores. But when we turn to examine methods in actual use for

Jan 1, 1900

By P. H. Dudley

When we see the magnificent passenger-trains of from 8 to 12 coaches, drawn by locomotives weighing from 100 to 110 tons, at speeds of from 50 to 60 miles per hour between terminals, to make a schedule of 45 miles per hour, and freighttrains of from 50 to 75 cars of 60,000 pounds capacity, drawn by one locomotive, it is hard to realize that it lacks a few months of fifteen years since my pioneer 5-inch 80-pound rail for the United States was laid by the New York Central aid Hudson River Railroad Co., in July, 1884, on the Harlem line. Shorter passenger-trains, of from 4 to 5 coaches, are run much faster, notably the Empire State Express, the schedule of which for the 440 miles between New York and Buffalo requires 53.3 miles per hour, calling for a running-speed, for much of the time, of from 65 to 75 miles per hour, while higher speeds are very common. On other railroads laid with my 5 1/8-inch 80-pound rail, speeds of from 60 to 75 miles per hour obtain in daily practice. On many of the important railroads east of the Mississippi high speeds of from 60 to 70 miles per hour are part of the daily service. So many instances of speeds of 90, and even 100, miles per hour have been recorded that they must be considered as likely to occur on important lines, and provision must be made for them in the track. Solid mail-trains of from 6 to 8 cars are run from New York to Chicago, 1000 miles, in twenty-four hours; and, commeneing with the present year, shorter trains are running from Chicago to San Francisco, 2000 miles, in three and one-half days. In the freight-service equally important progress has been

Jan 1, 1900

By Frank Soulé

Secretary E. H. Benjamin, of the California Miners' Association, has proposed and begun, in co-operation with the testing laboratory of the University of California, at Berkeley, a series of tests which should prove of great interest and practical use to all persons making extensive application of steel wire cables, and especially to miners who run them in deep mines. Mr. Benjamin is endeavoring to obtain pieces of cable both new, and old and worn, from every deep mine of importance on the Pacific Coast, together with all the data obtainable concerning their manufacture and particular use. Pieces from each sample will be broken ill the laboratory before mentioned: and as far as possible the effects of winding around drums or pulleys ; of sudden starting and stopping when loaded; of heavy shocks, and of the general wear and tear of the cables, will be ascertained by these tests. The Olsen testing-machine of 200,000 pounds capacity will be used to break the cables, and the rupturing force, in different instances, will be applied slowly and also rapidly, in order to make the tests comparable as far as possible with the practical use of the cables themselves. All information and data available should be obtained for each specimen sent to the laboratory, the name of the manufacturer, the date of making, strength of cable when new and unrusted, as well as the circumstances and conditions of the practical use of the cable. Having this information before us, we shall be able to tell, approximately at least, the effects of age, rust, wear and tear, shocks, etc.; and perhaps be enabled to draw the line of limitation beyond which it would be no longer safe to use a cable of known manufacture. Moreover, by means of such tests we may, perhaps, he able to recommend worn cables for other uses, less severe in character, thereby prolonging the life of their effective usefulness. When we consider the great number of miles of steel cable now in use, and of the greater number constantly being manu-

Jan 1, 1900

By E. H. Barton

The necessity, on the Pacific Coast and throughout the semiarid regions in particular, of the conservation of waters for agricultural, industrial and mining purposes has forced itself upon the minds of those directly or indirectly interested in these industries. To meet the requirements of the case, storage must be provided for the flood-waters so abundant during the rainy season in order to insure a constant and unfailing supply during the summer months. Such storage can only be obtained, in the greater number of instances, by the erection of reservoir-walls of great height. The feasibility of employing earth or timber in the construction of such high dams is questionable, especially when (as is often the case) they must be placed in torrential streams. The experience of recent years with masonry dams, throughout this and foreign countries, has demonstrated that such dams, when intelligently and correctly designed and properly constructed, will meet the requirements of larger storage by means of increased height. The failures of masonry dams have been few; only two of any consequence being on record, namely, that of the Puentes dam, in Spain, in 1802, and that of the Habra dam, in Algiers, in 1810.* On the other hand, the failures of wooden and earthern dams are innumerable. The following are some of the most important structures constructed in recent years. The list is taken from Mr. Wegmann's book, just cited: The Furens, Zola, Ternay, Ban and Verdon dams, in France; the Nizar, Lozoya, Villar and the two Hizar dams,

Jan 1, 1900

By Min Sunn Ye, Wei Wang, Huawen Xiao, Kai Yao, Fook Hou Lee, Siang Huat Goh

"Previous research have shown that introducing fibers to cement soil mixture is effective in improving the ductility as well as maintaining the strength of cement-treated soil. A good knowledge of stiffness of the improved soil at small strain is essential for realistic predictions of ground movements that may affect adjacent buildings or underlying infrastructure. This paper presents a triaxial system with local strain measurement developed for studying shear modulus degradation of cement treated clay with fibers. Cylinder specimens (70mm diameter by 140mm height) with 50% cement, 100% water, 0% to 1% polypropylene fibers by mass, and 7 days of curing period were used. A local strain measurement system with floating type miniature submersible LVDT is introduced in this paper. Configuration of the mounts including the pin size, length and distance are presented and discussed. Based on the experimental results, a reasonable configuration of the mounts is recommended for fiber reinforced cement treated clay. Results showed that the proposed local strain measurement system is effective for testing the shear modulus degradation of cement treated clay with fibers under both unconfined and confined condition. Comparisons with results from resonant column and bender element tests served to verify the reliability of the local strain measurements using the proposed method.INTRODUCTIONIn many geotechnical engineering problems, the operational strain domain ranges from 10-3% to 10- 1%. A good knowledge of stiffness at small strains is essential for realistic predictions of the ground movements that may affect adjacent buildings or underlying infrastructure. As such, during the last 3 to 4 decades, the importance of using the small strain stiffness of soils for the design of foundation and underground structures has widely been accepted. Triaxial testing has been widely used to study the stress-strain behavior of soil in the laboratory. However, the stiffness obtained from the conventional triaxial apparatus is usually far smaller than those back-calculated from field measurements. This is mainly attributed to the overestimation of axial strains from the external strain measurements, which usually includes compliance effects of the loading and load measuring system as well as sitting, bedding and alignment errors between sample and system (Baldi et al., 1988). The poor resolution of the external strain measurements is another important contribution. Therefore, conventional procedures are inappropriate for small-strain stiffness evaluation due to low accuracy and resolution."

Jan 1, 1900

By Andrew Middleton, Mark Wyatt

"The Brickworks Marketplace Project is a significant shopping centre development in inner north west Adelaide constructed by Badge Constructions in 2014 and 2015. The site was a former brickworks with a deep pit containing various extents of uncontrolled fill which was to remain on site, and with a remaining void up to 6 m in depth. The existing uncontrolled fill was improved using the High Energy Impact Compaction system, and the pit backfilled using a quarry crusher byproduct selected by trial and a recycled crushed concrete and bricks and compacted in deep lifts. This approach resulted in significant savings in compaction time, cost and building foundations. The settlements of various parts of the completed works have been monitored since February 2015 and this monitoring has demonstrated small settlements which meet the user’s constraints.INTRODUCTIONThe Torrensville Brickwork Markets project involved the transformation of a former brickworks and clay pit site into a regional 17,000m2 shopping centre, opening in June 2015.The site was a former brickworks with adjoining clay borrow pit. The clay pit had been partially backfilled over many years with ‘uncontrolled’ fill comprising ‘clean’ soil, bricks and kiln dust typically of the following thicknesses:??of the order of up to 7 m to 10 m but locally up to 15 m in the western part of the site??2 m to 5 m in the south-eastern part of the site; and??less than 0.5 m in the north-eastern part of the siteAnecdotal reports suggested compaction of some of the fill may have been undertaken, although this not able to be confirmed nor records obtained.Initially it was proposed to take up the existing uncontrolled fill, sort and recompact or remove to landfill, followed by backfilling in conventional means over 500,000 cubic metres of imported filling to a thickness of up to approximately 6m to backfill the former pit. This work represented a significant cost and was not economically viable.During early negotiations, the contractor proposed an alternative to retain and ground improve the existing filling on site, and to backfill the pit with fill placed and compacted in deep lifts, thereby significantly improving the economics, environmental and community impacts of the proposed works.The developer agreed to the proposal with the following performance criteria:??a settlement of =10 mm after 10 passes by the Impact Compactor (on existing subgrade areas);??a bearing capacity of 250 kPa for high level footings;??a maximum long term differential settlement of 40 mm (measured over 16 m), ie. 1 in 400; and??a minimum modulus of 40MPa."

Jan 1, 1900

By Sastry Putcha, Santosh Mummaneni, Swamy Avasarala, Vamshi Vemula

"This paper presents the results from a case study on the comparison of two strain acquisition instrumentation technologies, Geokon rebar strainmeters and Embedded Data Collectors (EDC) for the DC Water Main Pump Station project, in Washington D.C. These two instrumentation systems were installed by AVER in a single 18-inch (0.45 m) diameter augercast pile (with one-1.25 inch (3.175 cm) dywidag bar) at critical locations to determine the load transfer mechanism and establish a comparison between strain/load measured with these two systems along the pile. A quick static load test was performed on the test pile as per ASTM D1143 standard.Prior to the installation of the pile, a 24-inch (0.6 m) diameter outer casing was installed to the proposed cutoff elevation of -22.5 feet (-6.85 m) to discount the frictional resitance within the upper overburden zone. The pile was then drilled through the outer casing to the tip elevation of -65.02 feet (-19.8 m) with inner casing within the overburden zone. Strainmeters along with EDC were installed on dywidag bar at various locations and then wet set into the concrete following auger retrieval. The loads measured with EDC and Geokon sensors were within 15% percent of each other.PROJECT BACKGROUNDProject Background & Requirements:Like any other foundation piles, augercast piles are extensively used in the public and private sector structures in the United States for many years. It is a common practice to perform static compression (ASTM D1143), tension (ASTM D3689), and lateral load tests (ASTM D3966) depending on the project requirements. In recent years, embedded strain sensors, manufactured by Smart Structures, USA has gained prominence for its use to collect both static and dynamic measurements for driven piles. In addition, AVER has successfully used EDC for collecting long term static measurements for an abutment drilled shafts for I-95 Hotlanes project in Virginia, USA.Geokon sisterbar strain gages are widely used in the foundation industry to monitor the load transfer mechanism within pile foundations throughout the world. As the Geokon strainmeters are vibrating wire and are welded to a sister bar, there is often a debate within the engineering community with regards to what modulus to use when converting measured strains to loads. EDC sensors, unlike Geokon strain gages are embedded directly into the concrete and therefore do not have the same concern."

Jan 1, 1900

By J. Gniel, L. King, C. Gaudin, C. O’Loughlin

"This paper presents some recent advancements in centrifuge modelling, which enable the installation of displacement piles to be performed in-flight while measuring ground responses. Details and results are provided from a series of experiments where 21 full-displacement piles were installed into a sample of consolidated kaolin clay at 40g. The piles were pushed into the sample at a constant rate of penetration, with installation reaction loads and pore pressures measured. Insight into the installation effects of the full-displacement piles was obtained by undertaking in-situ testing pre- and postinstallation of piles. The findings show that centrifuge testing has the potential to play an important role in furthering the current understanding of displacement pile behaviour and installation effects.INTRODUCTIONDisplacement piles and displacement ground improvement columns cause soil to undergo significant distortion and shearing during installation, which alters the soil properties. It is essential to consider these changes in soil properties to estimate the behaviour of pile foundations with higher degree of accuracy. However, the installation effects of displacement piles are widely considered as one of the most difficult geotechnical mechanisms to model, both analytically and numerically, and experimental data is needed to advance the current state of knowledge.Theories, analytical and semi-analytical, have been developed to describe the displacement pile installation process. Randolph et al. (1979) applied the cylindrical Cavity Expansion Method (CEM) to model the installation of a displacement pile in a fine grained cohesive soil. However, cylindrical CEM only considers the field variables in radial coordinates, and hence the soil-pile interface can only be modelled as a frictionless material. Baligh (1985) introduced the Strain Path Method (SPM), which assumes soil flows around the tip of a displacement pile. SPM was shown to model the stress and strain fields, particularly within close proximity to the pile, more accurately compared to the cylindrical CEM. While these methods account for the installation effects of a displacement pile and can be used to estimate a resulting ultimate bearing capacity, they are unable to describe the load-settlement behaviour of such piles. With the added complexity of group effects, existing analytical methods do not provide a means to accurately calculate the ground response to the installation of a group of displacement piles in a cohesive soil.The advancement of computational power, numerical techniques and constitutive models has improved the accuracy of numerical analysis, particularly in regard to modelling pile installation. However, even with advanced techniques, Finite Element Method (FEM) suffers a number of disadvantages due to the large deformations, which results in mesh distortion and tangling. Mesh-free methods such as Discrete Element Method (DEM), Smoothed Particle Hydrodynamics (SPH) and Material Point Method (MPM) are the next generation of computational techniques that are able to deal with large deformation problems. However, these advanced techniques are computationally expensive, complex and yet to be incorporated into commercial packages. Such methods are considered to still be in the development stage and are yet to provide a complete solution to pile installation problems."

Jan 1, 1900

By Stuart Coutts

"This paper presents an overview of the author’s experience related to the assessment of the base capacity of straight shafted and enlarged-base bored piles in sand. A design approach based on CPT qc is described which has been calibrated using a database of load tests. The importance of correct installation techniques with instrumentation are illustrated and a discussion is presented on the current use of high strain dynamic testing to validate compliance with design. An example of a recent project with high quality instrumented load test data illustrates the close match to the proposed best practice approach and also highlights the importance for consideration of the effects of stress relief for deep foundations installed in deep excavations.1 INTRODUCTIONContinuous Flight Auger (CFA) piles are the bored foundation pile of choice for sand deposits across Australia. The evolution of the determination of the base resistance of CFA piles has been shaped by available investigative techniques, calculation methods, and calibration of designs with laboratory and field testing. The Cone Penetration Test (CPT) has been widely used in Western Australia (WA) where the test has been commercially available via multiple contractors for more than 25 years. On the East coast, the adoption of CPT testing has been slower with a transition from traditional Standard Penetration Testing (SPT) still occurring. Dynamic pile load tests are often used to derive parameters. The influence of pile installation on performance is commonly misunderstood and is an important element on any discussion of pile capacity for CFA pile types. The interface between the base of the constructed pile and the in-situ soil has an influence on capacity such that a poorly constructed pile base will have limited (if any) contribution to pile performance within the normal working range, generally within a 10 mm movement. The research presented in this paper pertains to CFA piles (no drilling fluids) and enlarged base piles constructed using CFA techniques under drilling fluids such that clean pile/base interface is targeted. Developments in modern piling equipment and instrumentation allow the pressure and volume of delivered concrete/grout to piles to be accurately monitored at various stages of installation such that repeatable ‘best practice’ can be achieved. The changes in soil conditions that occur due to the disturbance of the install technique are also important.Although the results of this research are likely applicable to bored piles, the interface between the pile and in-situ soil (shaft and base) need to be considered for various installation techniques. The effects of stress relaxation (due to removal of soil above pile base and adjacent shaft), time to concreting, and the zone of disturbed soil around the pile shaft are paramount.2 INSTALLATION CONSIDERATIONS The pile mix (concrete/grout) and interface with the in-situ soil are also an important consideration. For example, coarse grained, poorly graded, dry, clean sand will be partially permeated by most pile mixes; such that the influenced soil will be enhanced and in instances the overall effective pile dimensions increased. Permeation of the disturbed zone of a pile or anchor shaft along with scale effects (Lehane 2009) can have significant effect on shaft capacity and shaft frictions significantly exceeding expected are not uncommon based on ‘theoretical’ dimensions. Advancements in mix technology and mix techniques also have a large influence on the pile/soil interface. The ability of the piling rig and augers to excavate a plumb and gauge hole can also have a large influence on the zone of soil disturbed adjacent the constructed pile with a resulting influence on capacity."

Jan 1, 1900