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By I. C. Edwards, D. C. Smith

THE milling plant of Bicroft Uranium Mines Limited at Ban-croft, Ontario, was one of the first in Canada to employ ion excl1ange for the selecti1•e recovery of uranium from acid leach liquors. The ion ex-change circuit started operating early in November, 1956, and by June 1 I959, had handled more than two million tons of pregnant solution containing I,830,000 pounds of U3Os. Each column had been saturated and eluted about 430 times. The ion exchange columns are the conventional fixed bed type. Uranium is eluted from the resin with a sodium chloride-sulphuric acid solution and is precipitated continuous-ly with magnesia. After filtering and drying, the precipitate, or "yellow cake," is packaged in drums for shipment to the refinery.

Jan 1, 1962

By W. R. Crank

[Rock bursts are phenomena associated with mining operations, particularly with deep mining, although they occur throughout a wide rump, of depth, from 600 feel downward. The intensity is usually in direct proportion to the depth, varying from a loosening and sloughing off to a violent rupture, giving rise to the term, "explosive rock." The more or less violent breaking of rock in mine working, tins been variously designated as " flaking," "pressure hoists," "strain bursts," "bumps," "quakes," and "air blasts," which indicate opinions as to cause and effect. The term "air blast" lots probably beat most widely used, and naturally so, as a more or less rapid movement of air often accompanying the more violent phenomena of rock failure. Furthermore, there is an implied if not definitely expressed degree of magnitude in the action designited by a given term and in the cause and character of the action. For example. flaking, pressure bursts, and quakes are terms ranged to indicate action of increasing magnitude; and pressure bursts, strain bursts. bumps, and quakes are ranged according to the cause and character of the action.]

Jan 1, 1929

Editor’s note: As usual, the June issue features an industrial minerals review. And some thanks are in order. Thank you to the industrial minerals annual-review editor, to the technical committees chair and vice chairs and to the authors of the individual commodity profiles. Jim Norman of GeoTrans Inc. is the industrial minerals annual-review editor. William Langer, U.S. Geological Survey, is the chair of the SME industrial minerals technical committees and the vice chair of the technical committee for construction materials. Other technical committee vice chairs include: •Lucy McCartan, U.S. Geological Survey, agricultural minerals. •Steve Herron, Oglebay Norton Performance Minerals, ceramics and refractory materials. •Srinivas Veeramasuneni, U.S. Gypsum, chemical raw materials. •Ismail Yildirim, Imerys, fillers and pigments. •Charles Landis, BPM Minerals, sorbents, filters and process aids. •Ray Harris, Wyoming Geological Survey, specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of the readers, the editors thank them

Jan 1, 2004

By A. S. Prokopovitsh

A spectrophotometric method for the determination of small amounts of copper in tungsten metal powder using the principle of solvent extraction has been developed by the Federal Bureau of Mines. The metallic sample is dissolved in hydrogen peroxide, tartaric acid added, the pH adjusted, and the excess peroxide destroyed by boiling. Copper is reduced to the cuprous state, and the reagent neocuproine (2,9-dimethy1-1,10-phenanthroline) is added to form a colored complex with the copper. This colored complex is then extracted into chloroform and the absorbance of the separated chloroform layer measured on a spectrophotometer. Copper contents as low as 1 p.p.m. (parts per million) can be determined. The method is limited to finely divided tungsten powder. The interest of the Bureau of Mines in developing more sensitive methods for the determination of trace impurities in high-purity tungsten prompted an investigation of the possibility of using solvent extraction-colorimetric methods. The organic reagents now commercially available make possible many extremely sensitive colorimetric methods for the determination of metallic ions. Extraction of the colored complex into a small volume of organic phase can be used to further increase sensitivity (4) .4/ This general approach has the added advantage that no special equipment beyond that normally found in an analytical laboratory is required.

Jan 1, 1961

By D. van der Veen

Mining companies and contractors are looking at Wirtgen Surface Miners to provide flexibility at their operations. Wirtgen Surface Miners have been used in the surface mining industry for over fifteen years. The principle behind the Wirtgen Miner is a rotating drum equipped with tungsten carbide tipped cutting tools that excavates and sizes the material. The drum helix augurs the mined material to the center of the drum where it is loaded onto the primary conveyor belt. From there the material is conveyed to the discharge belt and into a truck bed. The cutting drum is located in the center of the machine, near the center of gravity. This permits the machine to cut hard materials as the entire machine weight is converted into cutting forces. Conventional mining practices are process, equipment, and labor intensive. Furthermore, strict environmental requirements pertaining to noise levels, dust pollution, and blasting, near buildings or urban areas, limit the application of conventional methods. Mining/ Construction contractors are using Wirtgen Miners in various limestone excavation projects, such as highway expansion projects, and new roads in housing developments. Mining companies in the industrial minerals and coal industry are using Wirtgen Miners to load directly onto trucks, eliminating the rehandling process and ultimately, primary crushers.

Jan 1, 2002

By Bruce Mennie

PT Freeport Indonesia (PTFI) operates copper and gold mining operations in a mountainous area of the Mimika regency, near Tembagapura, Papua (formerly, Irian Jaya), Indonesia. The mining and concentrating operations typically produce 240,000 metric tonnes per day of Copper and Gold ore from the combined mining of an 80,000 tonne per day (ore) block cave operation (DOZ Mine) and a 160,000 tonne per day (ore) open pit mining operation (Grasberg Open Pit). The Grasberg Open pit mine will be complete in 2016 at which time PTFI?s operations will convert to Underground. Mining operations will transition from today?s mixed surface and underground operation to full underground mining over the next 6 years. This paper reviews the history of Redpath?s relationship with PTFI, beginning with a raiseboring contract in 1981 and evolving into vertical and horizontal development contracts of up to 37,700 equivalent metres of lateral development and 4,000 metres of vertical development in 2011. An overview of the current operations (PTFI?s Grasberg Open Pit and DOZ Underground Mines) and transition period (challenges for the transition from current to future underground mines) is presented with details of development of common underground infrastructure and future mines; Big Gossan Mine, DMLZ Mine, Grasberg Block Cave Mine, and the Kucing Liar Mine.

Oct 1, 2010

By Michael H. Inglis

The Technology Application Center, in conjunction with the U.S. Bureau of Mines Liaison Program, is studying the use of Landsat data for the monitoring of coal surface mine reclamation activities. Landsat may provide sufficient information to reduce the number of on-site inspections now required. The focus of the project has been the Navajo Coal Mine located in north- western New Mexico and operated by Utah International, Inc. On October 15, 1977, a field team recorded spectral measurements at the mine during the time of Landsat's overpass and a corresponding aerial photographic flight. Training sets were selected from the ground and aircraft data representing vegetated, graded, ungraded and natural environments. A supervised classification of the data was performed by the Stanford University Remote Sensing Laboratory then correlated to aerial photos and mine maps. The results, to date, have been very encouraging.

Jan 1, 1979

By W. W. Mullins, F. A. Nichols

Solutions are developed, assuming surface diffusion and both internal and external volume diffusion, for the relaxation of bodies slightly perturbed from spherical and cylindrical geometries. Combined with those previously published for the nearly planar case, these results provide a means of gaging the relative contributions of the two diffusional proc-cesses in any given case. It is shown that in all sintering experiments to date, and probably in any attainable in practice, surface diffusion has played the dominant role, although most previous authors have assumed otherwise. It is also shown that surface diffusion predominates in normal field-emission tip blunting and also for the coalescence of gas bubbles introduced into metals by a bombardment. The surface-diffusion solutions for a perturbed sphere are combined with previous results for volume diffusion to show that the inclusion of interface diffusion permits considerably larger spheres to develop in diffusion-controlled precipitate growth before the onset of instability. A mechanism is also proposed for the spheroidization of precipitate platelets as well as rods. In a previous paper1 the relaxation of a nearly plane surface to flatness by the combined action of the transport processes of viscous flow, evaporation-condensation (in a closed system), volume diffusion, and surface diffusion has been analyzed under the assumption that all surface properties are independent of orientation. In this treatment, criteria were developed for deciding which process predominates, and solutions valid in the latter stages of the sintering of small wires and particles to a plane were obtained. A numerical solution, valid throughout the entire particle-sintering process for the case of surface diffusion, was subsequently obtained by the present authors.' It was found that the analytic solution (which assumed small slopes everywhere) is accurate to within -10 pct when the maximum slope of the profile is less than 0.3; the wire-sintering problem has also been solved nu- merically for the case of surface diffusion and here again the results converge to the analytic small-slope solution at late stages of the process, the two solutions agreeing in this case to within 10 pct when the maximum slope of the profile is less than -0.6. The purpose of this paper is to extend the perturbation solutions to nearly spherical and nearly cylindrical geometries. We treat only the two principal diffusional processes, i.e., surface and volume, but for these geometries we discuss volume diffusion both inside and outside of the solid. Our results, when coupled with Mullins' solutions1 for nearly planar surfaces, provide criteria for gaging the relative contributions of surface and volume diffusion to the over-all transport process in three basic geometries. A very interesting feature in the cylindrical case is the occurrence of instability for longitudinal perturbations with wavelengths greater than the cylindrical circumference, a classical result. This instability of the cylindrical surface is applied to give a quantitative explanation for the often-observed "erratic" pore closure in the late stages of the sintering of wire compacts; also, the theory previously presented for the spheroidization of rod-shaped precipitates by surface (interface) diffusion' is expanded now to include volume diffusion inside and outside of the particle. The results for circumferential perturbations on a long cylinder allow quantitative estimates for gaging the relative importance of surface or volume diffusion in the early stages of the sintering of spheres or wires. The results here demonstrate clearly that surface diffusion has played a very important, if not dominant, role in all sintering experiments discussed in the literature, although the surface-diffusion contribution to the kinetics has usually been ignored. The results for the sphere (surface-diffusion case) are added to the results obtained previously by Mullins and sekerka3 concerning instabilities of a growing spherical precipitate particle (with interface diffusion disallowed) to obtain a general solution to this problem including interface diffusion. The inclusion of interface diffusion is found to increase significantly the range of stability of a growing spherical precipitate for typical metallurgical cases. The following assumptions are made: (i) the initial surface lies everywhere near and has a slope differing only slightly from that of the reference

Jan 1, 1965

By B. Simser, V. Falmagne

"Noranda’s Brunswick mine is a 10 000 t/d producer of lead-zinc-copper-silver ore that has been in operation since 1964. Mining of this multiple lens deposit is primarily by blasthole stoping techniques between 400 m and 1200 m below surface. The combination of a high overall extraction ratio, an overall steeply dipping tabular shape, and high horizontal stresses (twice the vertical) have elevated the induced stress regime to levels comparable to much deeper operations. Improved mine design, and a better understanding of how the rock mass responds to mining in high-stress environments is essential to improve overall recoveries and maintain safety. Seismic monitoring has proven to be an essential tool at Brunswick, for both short-term safety of workers, and long-term strategic planning.Practical case studies illustrate how seismic data, particularly source parameter information, can be used to measure the rockmass response to mining and improve mining layouts in difficult regions. As the global trend continues toward mining in deeper, higher stress environments (e.g., South African Witswatersrand Basin, Sudbury Basin) and as local extraction and thus ground stresses continue to increase in existing deposits, seismic monitoring will play a critical role in mining safely and economically."

Jan 1, 2004

The information age has definitely arrived and in fact has only begun to affect our business processes. Traditionally mining companies have been innovators and leaders with technology, but applying information technology systems to machines directly working on the mining extraction process poses challenges to those introducing the technology. Caterpillar is now presenting machine guidance and information systems for dozers, graders, blast hole drills, shovels, excavators, wheel loaders and trucks. These systems simply increase the flow of real information in real time and deliver it to the end users who can make informed decisions that effect real productivity gains and at the same time eliminate the role of the middle manager who used to monitor and control these activities. Technology also offers cultural changes that appear intangible, but offer significant gains to those that implement technology. Critics state that these intangible benefits are still available to traditional processes, however these intangible elements are never identified nor managed without the introduction of technology enhanced processes. The benefits of these technologies are real and dramatic, existing users offer impressive testimonials, but still the technology can be disproportionate in the time it takes to introduce to an operation. Caterpillar finds that senior to executive management needs to be a part of the technology introduction, to coordinate all departments and set technology strategies.  

Jan 1, 2000

By G. A. Bezuidenhout, J. P. T. Kapusta, D. K. Chibwe

"Peirce-Smith converters (PSCs) are extensively used in the copper, nickel, and platinum group metals industries. The typical converting operation involves lateral purging of air into molten matte through a bank of tuyeres. This blowing operation occurs at low pressure from the blowers, resulting in a bubbling regime that is considered inefficient from both a process and an energy utilization perspective. Inherent drawbacks also include recurrent tuyere blockage, tuyere punching, and low oxygen efficiency.Western Platinum embarked on a full-scale industrial evaluation of generating a jetting regime by using sonic injection. Prior to industrialscale tests, a numerical assessment to ascertain the feasibility of implementing sonic injection into a PSC was conducted. The work included flow characterization at high-pressure injection achieving sonic velocity at the tuyere exit. The 2D and 3D simulations of the three-phase system were carried out using the volume of fluid method together with the RKE turbulence model to account for the multiphase and turbulent nature of the flow.This paper discusses the key findings in understanding plume extension, velocity distribution, shear wall stress analysis, and phase distribution characteristics in the system. Plant trials are also discussed with reference to the commercial aspects of a full-scale implementation of sonic injection in the smelter."

Jan 1, 2015

By Douglas Talley

This report describes a 4-inch diameter borehole probe which contains a low light level TV camera, magnetic compass, light illumination source, bottom/water detector sensor and a pointing angle sensor. The camera viewing angle is at a right angle to the probe's body. All data from the sensor is multiplexed into the closed circuit camera video for transmission on a single 50 ohm coaxial cable to a surface control unit. Likewise control of the probe's power, zoom lens, focus, panning and aperture is accomplished via a down-link multiplexed on the same cable.

Jan 1, 1984

By A. L. Grabovski

The potential of eccentric cone crushers for fine crushing has been improved by increasing the swing frequency of the moving cone, balancing the crusher, ensuring uniform feed via a rotating funnel with sideways discharge, introducing hyperbolic motion and employing the inertia crushing method, but further improvements to the specifications of existing cone crusher designs are limited by the rigidity of their kinematic coupling. A new design has been developed which combines two crushing modes, stone on liner and stone on stone, each with its own advantages. The main aims are to produce finer materials and to reduce liner weight. The benefits include an increase of more than 10% in the output of fine particles, improved protection of the liner against wear, as a result of filling of the cavities by material being crushed, and the use of almost 20% less material in casting of the liner. The chamber can be used in place of the usual liners of fine cone crushers

Jun 21, 1905

"While control of dust-related diseases, the objective of the Generic Mineral Technology Center for Respirable Dust, is of prime importance from the human standpoint it is also essential to the economic well-being of the mining industry (FIGURE 23). Although significant progress has been made, the problem continues to be a major concern to the mining community. An increasing global demand for coal and other minerals means that production and the number of miners employed is on the rise. Therefore, the importance of this research to the mining industry cannot be overemphasized.The five areas of dust research are 1) control of dust generation, 2) dilution, dispersion and collection of dust in mine airways, 3) characterization of dust particles, 4) interaction of dust and lungs, 5) relationship of mine environment, geology, and seam characteristics to dust generation and mobility. Some experimental projects where the research is conducted almost exclusively in the laboratory may still rely on industry for imput. No industrial resources are necessary to the research of the non-experimental projects, for example computer modeling .The remaining research is classified as experimental and these projects do require interaction with industry in varying degrees. Periodic trips to mining sites in Western Pennsylvania, Southern Ohio, and West Virginia are necessary to record measurements or collect samples. Or companies may provide needed samples or equipment to the university for use in the laboratory. On several projects interaction is limited to advice or information supplied to the researcher by industry personnel."

Aug 31, 1989

By Jennifer Pell

Dunsmuir Ventures? Nanuq diamond project is located approximately 250 km northeast of Baker Lake and 170 km north of Chesterfield Inlet. It occurs at the intersection of the Wager Bay shear zone with the Keewatin Arch, a major long-lived crustal uplift. The newly discovered diamondiferous kimberlites at Rankin Inlet, Repulse Bay and on Melville Peninsula also occur along this arch. Kimberlite indicator mineral (KIM) sampling has outlined a distinct KIM train more than 35 km long and 6 km wide. Geomorphological studies, boulder displacements and dispersion of magnetite in tills suggest that glacial transport distances were on the order of 4 to 6 kms only. The presence of multiple sources within the main Nanuq indicator train would account for its length and breadth. A second train has been located on the west central part of the property and anomalous concentrations of KIM occur elsewhere. Pyrope garnets (G9?s and G10?s), diamond inclusion field (DI) eclogitic garnets and DI chromites were confirmed by microprobe analyses. Clinopyroxene thermobarometry indicates a cool geotherm, approximately 35 mW/m2, and that mantle within the diamond stability field was tapped. An aeromagnetic survey has identified a number of anomalies. Those with down ice KIM support will have ground geophysical follow-up and will be tested in a spring 2004 drill program. Dunsmuir is optimistic that this will lead to the discovery of a new kimberlite cluster on the Nanuq property.

May 1, 2004

By R G Warren

Most orebodies have cross-sections of less than 1 km2 and hence do not offer a particularly large target for exploration. Fortunately, although in the geological record ore deposits are small and rare and result from the exceptional coincidence of certain geological processes, these processes are mappable on a much larger, district to regional scale and constitute a mineral system in which the ore deposit is the central feature. A mineral system can therefore be defined as `all geological factors that control the generation and preservation of mineral deposits, and stress the processes that are involved in mobilising ore components from a source, transporting and accumulating them in more concentrated fonn and then preserving them throughout the subsequent geological history'. The mineral system concept emphasises that for many ore deposit types, although economically viable mineralisation may only occur on a scale of say, hundreds of metres, the total system of fluid-rock interactions that led to ore formation can extend over a distance of tens to hundreds of kilometres around the deposit. When mapped out, the total mineral system provides a far larger exploration target than the actual ore deposit itself. Important geological factors defining the characteristics of any mineralising system include: 1. sources of the mineralising fluids and transporting ligands; 2. sources of the metals and other ore components; 3. migration pathway; 4. thermal gradient; 5. energy source; 6. a mechanical and structural focusing mechanism at the trap site; 7. chemical and/or physical traps for ore precipitation. Many of these factors individually are common throughout time and space and are mappable on a regional scale. The delineation and empirical prediction of mineral systems can thus be approached by combining two components of metallogenic research. Firstly, the development of maps of regional geoscientific data and data sets of the distribution of factors significant for mineral systems in general. Secondly, the determination of the essential ingredients of particular styles or types of deposits in terms of mappable elements that any exploration program could focus on.

Jan 1, 1994

By J. E. Miller, W. E. DeVaney, L. Stroud

During a recent phase study of a natural gas, two stable equilibrium liquid phases were observed at temperatures below —200°F and pressures above 200 psi. This paper reviews the published literature on the occurrence of multiple equilibrium liquid phases and presents analytical data for the vapor and two equilibrium liquid phases of the liquefied natural gas at five experimental conditions. In addition, data for 30 conditions of two-phase equilibria are included. INTRODUCTION The low-temperature phase behavior of gases, most of which contained helium, has been investigated in the laboratories of the Helium Activity for many years. Since 1952, experimental studies of these systems have been continuous as part of the research program at Amarillo, Tex. Because of their value to private industries interested in participating in the Helium Conservation Program, several "Open File" reports containing phase equilibria data for heliurn-bearing natural gases have already been released by the Helium Activity. A paper containing information on the general phase behavior, operating criteria and extensive vapor-liquid data for two helium-containing systems was recently published.2 Additional publications presenting experimental data on the phase relationships of various gas systems are now in process and will be available in the near future. PREVIOUS EXPERIMENTAL WORK Although the formation of multiple liquids has been reported for various systems, to our knowledge this paper is the only substantiated evidence of a vapor-liquid-liquid equilibria in a naturally occurring gas. In 1940, Vink, Ames, and others13 reported the presence of two liquid phases in a hydrocarbon system consisting of mixtures of crude oils, solvents and natural gas. Eilerts and co-workers; published data on the recombined fluids from a gas-condensate well. This condensed gas, containing approximately 76 per cent methane and 24 per cent ethane-plus, exhibited two distinct liquid phases. Weinaug and Bradley 14 observed "unusual" phase behavior in a reservoir mixture. These workers postulated that the anomalous phase behavior was due to the "imminent formation of a second liquid phase". Botkin, Reamer, Sage and Lacey 1 studied two California crude oils that exhibited multiple phases. Kohn and Kuratal0 recently reported two equilibrium liquid phases in the methane-hydrogen sulfide system. Roof and Crawfordl1 and Eakin, et a16 also have reported experiments with binary systems that formed two stable equilibrium liquid phases. APPARATUS AND PROCEDURE A U. S. Bureau of Mines Phase Equilibrium Apparatus was used in conducting this study. The apparatus and procedures employed in its operation have been previously described3 and will not be repeated in detail ill this report. Briefly, the apparatus consists of a windowed cell which can be maintained within ±0.5°F for temperatures between room temperature arid -320°F. Pressure within the cell can be maintained within 0.1 per cent of gauge reading up to 800 psig. Equilibrium vapor and liquid samples are obtained in special containers4 for analysis by a mass spectrometer. Although the accuracy of the analyzer is about ±0.1 mol per cent, the reproducibility of the phase-equilibrium apparatus is considered relatively poor. Values reported from methane and nitrogen are considered accurate to ±l.0 and ±0.6 mol per cent. Data for ethane-plus in the vapor are accurate within 0.2 mol per cent; liquid-phase data for this aggregate compolnent are accurate within 1.5 mol per cent. For helium in the vapor phase, the analytical data are accurate within 0.2 mol per cent; liquid-phase analyses for this component were obtained by the charcoal adsorption method described by Frost8 and are accurate within 0.006 mol per cent. All of these references to the accuracy of reported values are conservative estimates based upon a statistical treatment of reproducibility data obtained with the apparatus.

Distillation of the large and growing greenhouse literature indicates that: ò Global warming has occurred over the past century or more; ò Build-up of CO2 (and lesser greenhouse gases) in the atmosphere is a fact; ò This build-up is likely to cause further global warming. It does not appear possible to conclude that the observed C02 build up and observed global warming are linked; nor is it yet possible to forecast global or regional climate variation with conviction. The dominant greenhouse gas is C02 with about half the warming potential of those gases emitted by man's activities; and about 80% of anthropogenic C02 emissions are from the burning of fossil fuels. Fossil-fuel C02 emissions arg divided about equally between the developed countries of OECD and the rest of the world. However C02 output growth over the past decade was about 4% for OECD and some 40% elsewhere. Population growth and pressure for better living standards will ensure continued higher growth outside OECD. Uncertainty about the impact of increasing C02 emissions on climate, and the long lead-times involved in limiting the increase in atmospheric C02 concentrations, are good reasons for taking action now. Australia accounts for about 275 million tonnes a year or just over 1% of the CO2 emitted from the world's consumption of fossil fuels, and the fight to control global emissions will be won or lost elsewhere. Australia's participation will be by wise conselt and by example. In view of the uncertainties involved, it appears premature to take actions that might place an additional financial burden on our hard-pressed country. However, much can be done now that makes good economic sense and has the added benefit of limiting the growth in Australia's CO2 emissions. Natural gas emits less C02 per unit of energy when burned than either coal or oil. Furthermore, new gas-fired power stations utilise energy at considerably higher efficiency than is the case today with coal or oil. Because of much lower capital costs, there is a compelling economic case for permitting natural gas to compete freely with coal in the Australian power generation market.

Jan 1, 1989

By A. D. Dalvi

With the current economic situation, the demand for nickel and other base metals has fallen significantly. More than 440 kt/yr world nickel capacity has been taken out of production within the last year, or more than 25% of the total [1]. This situation is similar to that at the end of 1970?s and it will take a number of years for the demand to recover to the levels before the economic downturn. In the meantime, the challenges facing the industry have increased due to diminishing ore grades, more inaccessible and complex deposits, mounting capital and operating costs and the various external pressures which include socio-economic, environmental, and energy challenges. All industries will be faced with paying the ?total ownership costs? in the future. This will only increase the burden on the industry. How to cope with this in what Thomas Friedman calls the ?Energy-Climate Era? [2] will be the most pressing challenge for the next generation of metallurgists and managers. It will force us to take a broader view of the problems and the solutions beyond mere technical. The metallurgists, engineers and project managers will have to look at the overall projects and their objectives in designing the solutions, requiring a top-down strategic approach.

Jan 1, 2009

By J. R. Thoenen

For several years the Bureau of mines has been investigating the characteristics of ground vibrations produced by quarry blasts. Considerable basic information has been obtained in the course of this study, and the results have been made known to the public through various publications listed in the accompanying bibliography. The studies have been confined to obtaining fundamental knowledge of the characteristics of the vibrations themselves, because it was evident at once that he problem was extremely complicated. It was felt that any attempt to predict the effect of a ground vibration on an' type of artificial structure would be useless until the complexities of building vibrations are better understood. As opportunity offered, teats wore made in various types of structures and the effects of vibrations from many different sources were measured. In one set of tests (5)4/, it was demonstrated that the behavior of a building as quite different if it was shaken by vibrations originating outside tae foundation walls than if the source of the vibrations was within the building; vibrations coming from the round outside seemed to shake the building as a single loosely-coupled structure, whereas mechanically induced vibrations within the house seemed to set floors and walls in motion as independent units, each of which communicated its own natural motion to the adjoining member, causing a very complicated movement that was impossible to interpret.

Jan 1, 1938