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By W. H. Bassett

IN their paper on the directional properties in cold-rolled and annealed commercial bronze,1 Phillips and Samans suggest that cupronickel, under distinctly different treatments, shows both "45° ears" and "90° ears. " Fig. 1 shows the ears on some cupronickel cups made some 17 years ago for bullet jackets for small arms ammunition. In this case the material heated to 425° C. had "45° ears, while that annealed at 950° C. showed FIG. 1.-CUPRONICKEL, 0.032-in. GAGE, CAST WITH MAGNESIUM. ANNEALED AT TEMPERATURES INDICATED (DEGREES CENTIGRADE) AND CUPPED. long "90° ears" when drawn with the same tools. The method of cupping, the shape of cupping tools, etc., were found to have very little influence on the earing tendency, but the deeper the cup was drawn, the higher the ears would be.

Jan 1, 1932

By N. H. Parker, J. G. Papailias, G. Gutzeit

In its many forms, the turbine has greater latitude of application than any other mixing device. It is readily adaptable to all tank shapes, from the shallow pan to the tall and narrow stovepipe. Although turbine mixers can be adapted to most tank conformations, experience has shown that there is a preferred shape for optimum efficiency in each service. In the accompanying drawings this relationship is illustrated by the shallower tank for slurry suspension. The taller tank is preferable for continuous staged systems, or maximum retention of the gas phase in absorption. No single turbine covers the entire range of these applications with maximum efficiency. The back-sloped blade offers maximum power economy. The straight blade develops a higher discharge velocity for the dispersion type of service requiring localized shear. The same high shear environment is provided by the back-sloped impeller with stator ring assembly, which permits the most positive discharge control, Fig. 1. Positive stream control is critical in solids suspensions.

Mar 1, 1956

By Charles Shamel

I FEAR most of the Institute members are already weary of the perennial controversy about the apex law. I feel that way about it myself now, though I have been guilty of considerable contribution to the discussion in the past. The discussion does not seem to perceptibly influence previously held views and I would not again break into print on the subject but for the urgent invitation of the Chairman of our, Law Committee. This energetic and able member has firmly determined to secure a revision of the mining law and among other things to eliminate the so-called apex provision from the U. S. mining statutes. He is, however, fair about it and has invited me to make "the strongest possible argument in its favor." I am suspicious that he is acting on the psychological principle that it is usually easier to convince an audience against a cause vigorously but unsuccessfully defended than against one wholly mute. Nevertheless, I realize that personally he wishes me no harm, much as he hates the apex law, and so am willing that the Institute have whatever benefit may accrue from my taking up again the unpopular side of the discussion. I say this because the attitude of a large part of our "articulate" membership seems irreconcilably hostile; their minds are made up; favorable consideration is foreclosed; and they become impatient and even sarcastic at any attempt to elucidate a favorable view of the apex law. The exact question for discussion at the present time is not whether on abstract, or any other considerations, the apex law is the best possible rule, but the very different proposition whether, after nearly 50 years of statutory life and much longer as a practically universal miners' custom, it is now just and expedient to repeal the apex law.

Jan 4, 1914

By Howard Scott

INVAR is the preeminent low-expansion metal by virtue of the fact that it can be prepared with a zero coefficient of expansion at atmospheric temperature. This fact suggests that there is little room for improvement in the expansion properties of the low-expansion nickel steels. The inference is true, however, only so far as the expansion at and near atmospheric temperature is concerned, because the expansivity of invar starts to increase rapidly on heating above 100° C. and soon reaches the value of copper. Guillaume1 met this situation by increasing the nickel content above that of invar. By that expedient, alloys having low expansivity under higher temperatures were obtained, but not without a large increase in minimum expansivity. The increase in minimum expansivity with increasing nickel content severely limits the technical applications of these alloys at high temperatures. Prospects of improving the expansion characteristics of the nickel steels is offered by alloying. Search for an advantageous alloying addition by analogy with other alloy systems, however, is not productive because the low-expansion characteristic is unique with that system. The rule of mixtures usually gives a fair value of the expansivity of other solid-solution alloys, but in the iron-nickel systems gives a value of 18 X 10-6 per deg. C. whereas the actual value is 1 X 10-6 per deg. C. Apparently suitable additions are not to be deduced from such ingenuous considerations. Recognition of the fact that the temperature range of low expansivity in nickel steels is terminated with loss of magnetism affords a more promising basis for the selection of an advantageous element. One may expect from that fact that additions of nonmagnetic elements to the iron-nickel alloys are detrimental to the low-expansion characteristic. Indeed, carbon, manganese, silicon, copper and chromium are detri-mental to the expansion properties and no nonmagnetic element is reported to be beneficial. From the same viewpoint, the addition of a magnetic metal offers prospects of improvement. As two of the three ferromagnetic elements are already present in the

Jan 1, 1930

By B. E. Parsons

Curtailment of production of crude oil, to the extent of effecting an approximate balance in supply and demand, was a problem confronting the oil industry in California throughout the year 1930. At the beginning of the year, with drilling operations only slightly checked, the California industry faced a steadily increasing potential production, an actual production in excess of market requirements and stocks of crude oil and refined products which had reached staggering proportions. During the year, the intensive development of the Playa Del Rey field and extensions to several oil fields, together with flush production from numerous large wells from both new and old fields, caused a steady increase in the state's potential production to a record peak in November of 1,186,000 bbl. daily. Despite the burden of this steady stream of flush production and the handicap of incomplete cooperation in several fields, curtailment successfully lowered the trend of crude oil production in California, except for the period of an open-flow test to determine actual potential production in several important fields in February. Under the curtailment programs in effect, the state's production of crude oil for the year was reduced 22 per cent. under the production of 1929 and even slightly under the production for the years 1927 and 1928. The total stocks of crude oil and refined products were reduced 2.7 per cent. during 1930, as compared to an increase of 30 per cent. in total stocks of all products during 1929. Drilling operations were reduced 28 per cent. as compared to drilling activities during 1929. Voluntary curtailment of drilling programs by many operators, particularly the major companies, accounts for the greatest portion of the reduction in drilling activity. The decline in drilling activity at Santa Fe Springs and in the east-side fields of the San Joaquin Valley was more than offset by development in new fields and extensions to deeper zones of old fields. There were 755 new wells completed during 1930, as compared to 910 completions in 1929. At the close of the year, 220 wells were drilling in the oil fields of California, 9 of which were being drilled in search of deeper producing horizons.

Jan 1, 1931

By Ralph E. Esarey, G. F. Fix

The oil and gas industry in Indiana in 1938 showed considerable improvement over the preceding year. Most of the drilling and development during the year, as in the past several years, was in the Indiana portion of the Illinois Basin, but increasing interest was apparent in the old Trenton area, for possibilities of further production in the Trenton formation and the underlying St. Peter sandstone. Interest in all other portions of the state was at a new peak, since many areas have never been prospected. Natural gas production continued to drop during 1938, since new discoveries have not been able to keep pace with the rapid decline in older areas. Oil production increased considerably, chiefly through the discovery of new fields. Older fields contributed about the same quantity of oil during 1938 as during the preceding year. There were 159 wells completed in Indiana during 1938, an increase of 25 over the preceding year. Of these, 48 were oil wells, 41 were gas, and '70 failed to find commercial production. Forty-three, or about 20 per cent, were wildcat. Six of these were productive—three oil wells and three gas wells. Thirty-nine wells on which operations started during the year had riot been completed by Dec. 31. Fourteen others were temporarily abandoned, with the possibility that several will be drilled to completion in the near future. A new oil field (Heusler) was discovered in May 1938, in sees. 1 and 12, T. 7 S., R. 12 W., Posey County. Production was found in the Waltersburg (Upper (Chester) sandstone at a depth of approximately 1775 ft. At the close of the year, Heusler field had nine producing wells and two drilling. The Point township area, Posey County, near the confluence of the Wabash and Ohio Rivers, held promise of good production from the McClosky lime, but offsets to the, discovery well had only shows of oil. The discovery well declined rapidly in production arid was finally plugged. In the Oaktown field, Knox County, a wildcat came in with a good flow of gas, extending the field to the east, and proving considerably more acreage. A new gas area was discovered in Sullivan County, and four good wells were completed. The discovery well was in sec. 35, T. 8 N., R. 10 W., and had an initial

Jan 1, 1939

By Ralph E. Esarey, G. F. Fix

The oil and gas industry in Indiana in 1938 showed considerable improvement over the preceding year. Most of the drilling and development during the year, as in the past several years, was in the Indiana portion of the Illinois Basin, but increasing interest was apparent in the old Trenton area, for possibilities of further production in the Trenton formation and the underlying St. Peter sandstone. Interest in all other portions of the state was at a new peak, since many areas have never been prospected. Natural gas production continued to drop during 1938, since new discoveries have not been able to keep pace with the rapid decline in older areas. Oil production increased considerably, chiefly through the discovery of new fields. Older fields contributed about the same quantity of oil during 1938 as during the preceding year. There were 159 wells completed in Indiana during 1938, an increase of 25 over the preceding year. Of these, 48 were oil wells, 41 were gas, and '70 failed to find commercial production. Forty-three, or about 20 per cent, were wildcat. Six of these were productive—three oil wells and three gas wells. Thirty-nine wells on which operations started during the year had riot been completed by Dec. 31. Fourteen others were temporarily abandoned, with the possibility that several will be drilled to completion in the near future. A new oil field (Heusler) was discovered in May 1938, in sees. 1 and 12, T. 7 S., R. 12 W., Posey County. Production was found in the Waltersburg (Upper (Chester) sandstone at a depth of approximately 1775 ft. At the close of the year, Heusler field had nine producing wells and two drilling. The Point township area, Posey County, near the confluence of the Wabash and Ohio Rivers, held promise of good production from the McClosky lime, but offsets to the, discovery well had only shows of oil. The discovery well declined rapidly in production arid was finally plugged. In the Oaktown field, Knox County, a wildcat came in with a good flow of gas, extending the field to the east, and proving considerably more acreage. A new gas area was discovered in Sullivan County, and four good wells were completed. The discovery well was in sec. 35, T. 8 N., R. 10 W., and had an initial

Jan 1, 1939

By E. I. Organick, B. H. Golding

A simple correlation is presented for the prediction of saturation pressures in condensate-gas and volatile-oil mixtures. Saturation pressure is related directly to the composition of the mixture with the aid of two generalized composition characteristics, B, the molal average boiling point, and W, the modified weight average equivalent molecular weight. The need for hydrocarbon equilibrium constants is entirely eliminated. Only the values of the two conlposition parameters need be obtained, and these are calculated in a simple and reproducible manner from the stream analysis of the mixture and the ASTM distillation for the heavy ends. The correlation is given .in the form of a set of 14 working charts in which saturation pressures, either retrograde dew points or bubble points, are plotted cs temperature, forming partial phase envelopes for mixtures having discrete values of the composition parameters, B and Wul. A locus of critical states on each chart intersects the partial phase envelopes, distinguishing retrograde dew point pressures from bubble pressures. A comparison Between experimental and predicted saturation pressures reveals that: the probable error of the predicted values, when considering the data as a whole (214 experimental points), is five per cent; for high gasjoil ratio condensate fluids (approximately 40.000 or more cu ft/bbl) the probable error is about 8 per cent. In either case, however, the probable error is comparable with the overall uncertainty of the data from which the correlation is derived. INTRODUCTION There is a present need for a simplified, yet reasonably accurate method for predicting upper phase boundaries of reservoir fluids. In the case of high gas/oil ratio fluids, namely the so-called highly volatile oils and the condensate gases, no simple method, accurate within 5 to 10 per cent, is now available by which bubble point and retrograde dew point pressures may be predicted. In order to calculate the upper phase boundary of a volatile reservoir fluid, using correlations now available, it is necessary to find and employ the proper K-values (equilibrium volatility ratios of the hydrocarbons in that fluid). This process of finding the Proper K-values usually involves a double trial and error computation. Since the K-values are in themselves dependent upon the composition of the fluid, their use in the calculation of a saturation pressure actually represents an unnecessary complication. The correlation described in this paper relates saturation pressure directly to the stream composition, entirely eliminating the need for K-values. The only data required to calculate the Stream composition are obtained from the customary low temperature fractional analyses of separator gas and liquidt and from the ASTM distillation of the c,+ fraction of the separator liquid. A considerable simplification in the procedure for predicting saturation pressures is thereby effected without significant loss in accuracy. BASIS FOR A CORRELATION Empirical relationships between the saturation pressure and the composition of the fluid in question have already been partially explored by one of the authors.V n particular, a relationship between the critical pressure for a hydrocarbon mixture and its composition was developed. The critical pressure is in reality a saturation pressure, as it repregents a limiting case either of a dew point or of a buhhle point pressure for any given mixture. It was found that the critical pressure may be correlated as a function of two generalized composition characteristics or variables. One characteristic expressed a molal average prop-erty, the other a weight average property of the mixture. Specifically, the molal average boiling point (MABP, or B as it

Jan 1, 1952

By W. P. Evans, R. W. Buenneke

Warren and Averbach's multiple order, Fourier method was applied to solid specimens of SAE 1045 steel. The material was hardened to three hardness levels and specimens of each hardness were shot peened to three intensities. Particle size, root-mem-square strain, mean strain, md macro residual stress were determined for each. Microstrains caused by either hardening or peening varied markedly over microregions. In general, increasing the hardness or peening intensity increased the rms strain and decreased the particle size. Similar effects were observed by varying hardness and peening intensity independently. At a Rockwell hardness of C 50, peening had little effect on line broadening, but both mean strain and macro residual stress increased. Mean strain was independent of column length. Induced macro residual stress by peening was affected most by initial hardness, but not by specific peening intensity. The purpose of this work is to establish the state of residual strain and particle size by X-ray diffraction in hardened and cold-worked plain carbon steel and attempt to relate these X-ray measured parameters to fatigue performance. X-ray line broadening (and its micro implications), along with X-ray residual stress (and its macro implications), may be basic indicators of the inherent fatigue resistance of the material. X-ray line broadening is caused by variable lattice strains and small particle size. Both are a result of plastic deformation which accompanies hardening or cold working processes. Therefore, X-ray line broadening is a good measure of both. warren1 has recently reviewed the Warren and Averbach2,3 Fourier analysis of line broadening. Strain and particle size effects can be separated because broadening due to particle size is independent of order of the diffraction peaks, while broadening due to strain is not. Microstrain is obtained as a root-mean-square strain averaged over discrete distances within the crystals causing diffraction. These distances are quite small, varying from 10 to 10081, and may be interpreted as the gage length over which the strains are averaged. Because of their variable nature, the X-ray line is broadened. The plot of rms strain vs distance (or column length) within the specimen gives a measure of their variability. Small particles also cause X-ray line broadening as already mentioned. A particle is interpreted as a region within a crystal or grain which diffracts X-rays coherently. This region is one of given orientation and may be bounded by a small angle grain boundary, dislocations, a twin boundary, or a stacking fault. The present work covers measurement of X-ray line broadening and macro residual stress on an SAE 1045 steel, quenched and tempered to various hardnesses. Various amounts of cold working were produced by shot peening the surfaces to various Almen intensities. Particle size, root-mean-square strain, and mean strain were calculated from the Fourier coefficients of the X-ray diffraction profiles in a direction normal to the peened surface. No effort was made to separate the various causes of particle size broadening. Macro residual stresses were reported in directions parallel to the peened surface. I) X-RAY METHOD The Fourier coefficients were determined for the 110 and 220 X-ray profiles. They were corrected for instrumental broadening by the method of Stokes,4 using an annealed reference specimen of similar geometry presumed to be free from broadening due to small particles and distortions. The nth Fourier cosine coefficient, A,, is related to a particle size coefficient, Ap, and a distortional coefficient, ADn, by the equation:

Jan 1, 1963

By W. H. Kantner

In this paper, no attempt will be made to theorize on subsidence. Only known data and actual facts will be given, with a few exceptions noted where other factors and outside influences tend to change subsidence directly resulting from porphyry caving. The area under observation is known as the Southeast Extension of the East orebody. The orebody is irregular in outline and dips to the south and the east, extending in depth from about 425 ft. below the surface to 1050 ft. below the surface. In the upper horizon, the orebody is about 400 ft. long and 150 ft. wide. At 720 ft. below the surface, the ore outline is approximately 450 by 170 ft.; 70 ft. below this, it is 500 by 110 ft., with an extension at the north end to the east 270 by 120 ft. From this elevation to about 900 ft. below the surface, the ore spreads out to the cast and south, being about 700 by 500 ft. between these vertical limits. Below this it pinches out and at 1060 ft. below the surface is only 100 by 100 ft. The nearest point of the orebody—which is on the northwest side—is 600 ft. 'southeast of the Sacramento shaft. The country rock is all porphyry. Fig. 1 is a vertical east-west section showing orebody and original surface. The surface over the orebody was fairly regular and in this area and adjacent to it were portions of the surface plant, roads, and the main plant railroad to the concentrator. Fig. 2 is a map of the surface over the porphyry area. Caving operations started in April, 1925, at the approximate top of the orebody. The first lift was on the 600-ft. level; the ore was extracted by means of the Morenci timbered slide method and was from 425 to 455 ft. below the surface over an area of about 22,000 sq. ft. This lift was finished in May, 1926. The second lift, on the 650-ft. level, was already in production by May, 1926, so extraction of ore was continuous. This lift was 48 ft. high and covered an area of about 30,000 sq. ft. The ore from this lift was extracted by means of a modified Morenci timbered slide method. This lift was finished in March, 1927. The direction

Jan 1, 1934

In accordance with the provision of the Constitution, notice is here given to all Members, Associates, and Junior Members, that the dues of the year 1918 will be payable on Jan. 1, 1918, at the office of the Secretary. The dues for Members and Associates are $12 per year and the sum of $3 additional is asked of those Members and Associates who desire to have the three volumes bound in the Institute's standard half-morocco binding. The dues of Junior Members are $5 per year.

Jan 1, 1918

By Edgar R. Kendall

A knowledge of the fundamental principles of locating, sampling, testing and evaluating materials is essential in prospecting for mineral aggregates. In this discussion, mineral aggregates will be considered sand, gravel, crushed stone and slag that are used as materials of construction. The quantity of mineral aggregates produced in the United States during the year 1935 for such purposes was roughly 165,000,000 tons, about 60 per cent of which was sand and gravel, 37 per cent crushed stone and 3 per cent crushed slag. The total value of this material was approximately $100,000,000. It is apparent therefore that the prospecting for suitable mineral aggregates is of considerable economic importance. In prospecting for mineral aggregates, the methods employed are the same whether the organization is large or small. In the large organization there may be available geologists for locating sources of supply, a land acquisition department to arrange for the necessary options or permits, engineers to do the sampling, a laboratory for testing, and a board of consulting materials engineers to make the final selection. Even small organizations must follow the same general procedure, though the responsibility for the selection of aggregates may rest with one man, who may or may not be an engineer, but who must depend entirely upon his own judgment. Locating the Supply The initial step in prospecting for mineral aggregates is the locating of suitable, adequate and economic sources of supply for the project in mind. Commercial plants in the vicinity should be investigated and a survey made of the existing structures that have been built of aggregates from these sources. If the structures are rather old and show no signs of deterioration, it is fairly good evidence that the aggregate is satisfactory. If materials of the proper quality can be obtained from commercial sources in sufficient quantity, and delivered to the job economically, it

Jan 1, 1942

By Edgar R. Kendall

A knowledge of the fundamental principles of locating, sampling, testing and evaluating materials is essential in prospecting for mineral aggregates. In this discussion, mineral aggregates will be considered sand, gravel, crushed stone and slag that are used as materials of construction. The quantity of mineral aggregates produced in the United States during the year 1935 for such purposes was roughly 165,000,000 tons, about 60 per cent of which was sand and gravel, 37 per cent crushed stone and 3 per cent crushed slag. The total value of this material was approximately $100,000,000. It is apparent therefore that the prospecting for suitable mineral aggregates is of considerable economic importance. In prospecting for mineral aggregates, the methods employed are the same whether the organization is large or small. In the large organization there may be available geologists for locating sources of supply, a land acquisition department to arrange for the necessary options or permits, engineers to do the sampling, a laboratory for testing, and a board of consulting materials engineers to make the final selection. Even small organizations must follow the same general procedure, though the responsibility for the selection of aggregates may rest with one man, who may or may not be an engineer, but who must depend entirely upon his own judgment. Locating the Supply The initial step in prospecting for mineral aggregates is the locating of suitable, adequate and economic sources of supply for the project in mind. Commercial plants in the vicinity should be investigated and a survey made of the existing structures that have been built of aggregates from these sources. If the structures are rather old and show no signs of deterioration, it is fairly good evidence that the aggregate is satisfactory. If materials of the proper quality can be obtained from commercial sources in sufficient quantity, and delivered to the job economically, it

Jan 1, 1942

By Harold Earle Cook

The purpose of this paper is to state briefly the inspection requirements of the Bureau of Ordnance, the specifications governing the inspection, and the physical and chemical properties of the steel used in the construction of ordnance for our Navy. It would be of interest to evoke discussion on points in these specifications which do not tend to insure the production of the very best material for the purpose intended. In other words, what requirements of our specifications are useless and also in what manner are our specifications deficient? It might be well at the start to answer the first criticism of this paper which will probably be made, and that is that the title does not agree with the subject matter. Considering metallographic work as covering only the macroscopic and microscopic examination of metals, this paper will have gone beyond the subject; but it is believed that a broader definition of metallography is that it is the study of the relation of the internal structure of metals and alloys to their composition and to their physical and other properties. The internal structure of steel is dependent on its physical and its chemical properties. These physical properties are dependent on the chemical composition and the mechanical and thermal treatment of the steel. So it seems that this subtitle would not be entirely necessary and that the title " Metallography of Steel for Ordnance Purposes" would cover a study, not only of what we can learn of macroscopic and microscopic examination, but broadly of the whole subject of the specifications, the fulfillment of the requirements of which produce the structural conditions revealed by macroscopic and microscopic examination. I will refer but briefly at the beginning to the microscope and its uses in our inspection. It is only very recently that the Bureau of Ordnancc has furnished certain of its inspection offices with a portable Tassin outfit for the microscopic examination of steel. Since that

Jan 1, 1916

By Norman Brown, J. V. Rinnovatore

It was found that a shear stress applied during the recovery had no effect on the amount of recovery if the stress was less than the instantaneous yield point irrespective of the direction of the stress. Large ajplied stresses during recovery had a marked effect, which depended on the direction of stressing. Single strain reversals at -72°C not only produced the Bausch-inger effect but also increased the flow stress. The increase inflow stress was attributed to vacancies, which have appreciable mobility at -72 °C. THEORIES I-' of recovery suggest that the internal stress field of the dislocations plays an essential role. Most investigations of recovery use time and temperature as the independent variables; however, here stress has been introduced as a variable in two ways: 1) by varying the internal stress field according to the amount of strain prior to recovery and 2) by applying an external stress during recovery. Tannen- baum and Kauzrnann studied the effect of applying a stress during recovery by measuring the change in creep rate after recovery; they found that stresses as high as 95 pct of the creep stress had no effect on recovery. Earlier, Wood and scrutton6 showed that an applied stress during creep increased the rate of poly-gonization. The experiment by Wood involved poly-crystalline aluminum whereas Tannenbaum and Kauzmann used a single crystal of zinc. In this investigation, zinc single crystals were used and deformed in a manner to prevent polygonization. Thus, the main difference between this investigation and that of Tannenbaum and Kauzmann is the use of the stress-strain curve instead of creep rate as the index of recovery. In addition, the applied stress during recovery varied

Jan 1, 1961

By Iichiro Omori

THE Mabuki process, a Japanese hearth process for the treatment of matte, uses the same princi-ple as the Bessemer steel process. The only difference between the two is that in the Mabuki proc-ess a hearth furnace, not a converter, is used. Though the hearth is not as good as the converter, the first cost is very low and the capacity is compara-tively small; so the process is most suitable for smelters FIG. 1.-PLAN AND SECTION OF HEARTH. having a small production. To construct the hearth, an excavation, 6 ft. in each dimension, is made in the ground and a drainage channel is dug at the bottom. Then all side walls are faced with stone or slag brick and the cavity is filled with fireclay or brasque, except the hearth at the top.

Jan 9, 1922

By M. Mathieu

The Rove tunnel is the means by which the canal from Marseilles to the Rhone Riverl penetrates the hills of Nerthe, lying between Mar- seilles harbor and Lake Berre, Fig. 1. The canal will communicate at sea level with both terminals. The original project planned a lock near the village of Marignane; but observations, pursued for more than three years, showed that the water surface gradient would average only 0.015

Jan 1, 1923

By M. Mathieu

The Rove tunnel is the means by which the canal from Marseilles to the Rhone Riverl penetrates the hills of Nerthe, lying between Mar- seilles harbor and Lake Berre, Fig. 1. The canal will communicate at sea level with both terminals. The original project planned a lock near the village of Marignane; but observations, pursued for more than three years, showed that the water surface gradient would average only 0.015

Jan 1, 1923

By Warren E. Holland, Leon H. Robinson

The pore pressure must be included in any discussion of the state of stress within a rock. Rock cylinders at elevated stress levels, loaded uniaxially to a stress less than the yield strength, can be fractured by holding the constraints constant and increasing the pore fluid pressure. This can be described in terms of the Mohr envelopes using effective stresses. The effective stress concept can simplify data with various confining and pore pressures. When the pore and confining pressures are equal, the pore pressure appears to be totally effective in reducing the confining pressure effects. The area over which the pore pressure acts has been the subject of some prior discussions. Terzaghi 1 defined boundary porosity as ". . . the ratio of that part of the area of the potential surface which is in contact with the interstitial liquid and the total area of this surface." His method of calculation included a discussion of splitting failure which was objected to by Mr. Kessler, National Bureau of Standards. The values calculated by Terzaghi were close to unity. Leliavsky,2 using unjacketed cement cores, reported that the interstitial fluid pressure appeared to act upon about 92% of the surface of failure. He concluded: "The fraction of the area of cross-section over which the internal pressure acts can therefore have nothing to do with ordinary porosity, and the results of the experiments tend to support Professor Terzaghi's views." In 1947 Balmer3 determined the boundary porosity of concrete when the confining and pore pressures were equal. He also found values close to unity. In 1948 McHenry4 published some of the results from the same equipment and included the first data in which the pore pressure

Jan 1, 1970

By Robert Glass Cleland

[PHELPS DODGE COPPER PRODUCTS CORPORATION OFFICE, 40 WALL STREET, NEW YORK 5, N. Y. OFFICERS Whipple Jacobs President Howard T. Brinton Vice-President Edgar P. Dunlaevy Vice-President Weightman Edwards Vice-President S. Allan Jacobs Vice-President]

Jan 1, 1952