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1

Effect of Time History on Long-Term Deformation of Gypseous Soils

Fattah Mohammed Y., Al-Shakarchi Yousif J., Al-Numani Huda N.

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 3

198--210

EN

The time-dependent behavior of three gypseous soils was investigated. The soils had gypsum content of 66%, 44%, and 14.8%. The mineralogical and chemical properties of the soils were determined. Two series of tests were performed. In the first, collapsibility characteristics were investigated for a long period (60 days) by conducting single and double oedometer tests. In the second series, the effect of relative density on collapse with time was investigated. The samples were compacted to 40%, 50%, and 60% relative density and then tested. The results of collapse tests showed that the relationship between the strain and logarithm of effective stress has two vertical lines. The first one represents the collapse settlement taking place within 24 h, while the second one represents the long-term collapse. The collapse potential (CP) in both single and double oedometer tests increases when the gypsum content increases from 14.8% to 66% and when the initial void ratio increases. The CP–logarithm of time relationship for soaked samples prepared at different relative densities under 800 kPa indicated that the CP increased with time for the soil sample compacted at 60% relative density and the increase was higher than those compacted at 40% and 50% relative density. The curves started with a straight line and then a concave downward curve was observed with a high strain. For samples compacted at 40% and 50% relative densities, the curves were interrupted by little soil collapses, while the third curve exhibited smooth relation following the collapse.

2

Effect of Machining Process Parameters and Number of Pass on Compaction Behaviour of Commercially Pure Aluminium Chips Consolidated by Equal Channel Angular Pressing (ECAP) Using Response Surface Methodology

Palanivel Ramaswamy, Vigneshwaran S., Alshqirate Abedalrzaq, Madhavan R., Venkatachalam P., Laubscher R. F.

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

357--370

EN

This work investigates the compaction behaviour of commercial pure aluminium chips (CP Al) produced during a machining operation and subsequently consolidated by Equal Channel Angular Pressing (ECAP). Empirical models were developed to describe the relative density and hardness of the compacted product of ECAP as functions of the initial machining input parameters including cutting edge angle (CA), depth of cut (DOC) and then the number of consolidation pass during ECAP. The models were developed utilizing response surface methodology (RSM) based on data from a central composite face centred factorial design of experiments approach. The models were then validated by using Analysis of Variance (ANOVA). The effect of input parameters on the relative density and hardness of the ECAP consolidated samples are presented and discussed including details as regards to the mechanical and microstructural properties. An optimum set of input parameters are identified and presented where the best relative density and hardness are demonstrated.

3

Verification of strength resistance of sandy soil using small scale penetrometer tests

Saleem Hiba D., Aldefae Asad H., Humaish Wissam H.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2021

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Vol. 30, No. 2

304--314

EN

This study focuses on utilizing cone penetrometer models to determine strength (resistance) of sandy soil and also assessment how the relative density and the angle of friction effects on the measured cone penetration resistance in sandy soil. Simple empirical equations are used also to determine the cone penetration resistance components such as the sleeve resistance and the tip resistance. Simple comparison is performed between the measured and calculated soil strength and well agreement is noticed between them.

4

The influence of ball milling processing variables on the microstructure and compaction behavior of Fe–Mn–Cu alloys

Ammar Hany R., Sivasankaran Subbarayan, Alaboodi Abdulaziz S.

Materials Science Poland

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2021

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Vol. 39, No. 3

410--429

EN

In the present study, twenty seven [(Fe–35wt%Mn)100−x–Cux] alloy samples were processed using high-energy ball milling, followed by uniaxial compaction under different processing conditions. The compressibility behavior in terms of relative density (RD) was examined with milling time (MT: 1 h, 5.5 h, and 10 h), ball-to-powder mass ratio (BPMR: 5:1, 10:1, and 15:1), milling speed (MS: 100 rev/min, 200 rev/min, and 300 rev/min), compaction pressure (CP: 25–1,100 MPa), and alloy composition (Cu content [CC]: 0 wt%, 5 wt%, 10 wt%). Particle size analysis using X-ray diffraction (XRD) and high-resolution scanning electron microscopy (HRSEM) combined with energy-dispersive X-ray spectroscopy (EDS) were applied for microstructural characterization. The experiments were conducted based on the central composite design of response surface methodology (RSM), and the results for the compaction behavior were examined with the input parameters. Analysis of variance (ANOVA) test was applied to determine the most significant input parameters. The attained results revealed that increasing ball milling parameters (MT, MS, and BPMR) resulted in significant enhancements in the microstructural features, such as improved elemental dispersion and occurrence of refined particles with substantial decrease in the crystallite size. On the other hand, increasing the input parameters exhibited a detrimental influence on the compactibility and RD of the alloys. In addition, increasing the CC resulted in a substantial improvement in the compressibility and RD of the developed alloys. The recommended combination of the studied variables includes MT for 5 h, MS for 150 rev/min, BPMR of 10:1, and 10 wt%Cu to attain an acceptable compromise of enhanced microstructure features, improved compaction response, and RD.

5

Experimental bearing capacity of eccentrically loaded foundation near a slope

Mansouri Tarek, Abbeche Khelifa

Studia Geotechnica et Mechanica

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2019

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Vol. 41, nr 1

33-41

EN

Based on the response of small-scale model square footing, the present paper shows the results of an experimental bearing capacity of eccentrically loaded square footing, near a slope sand bed. To reach this aim, a steel model square footing of (150 mm × 150 mm) and a varied sand relative density of 30%, 50% and 70% are used. The bearing capacity-settlement relationship of footing located at the edge of a slope and the effect of various parameters such as eccentricity (e) and dimensions report (b/B) were studied. Test results indicate that ultimate bearing capacity decreases with increasing load eccentricity to the core boundary of footing and that as far as the footing is distant from the crest, the bearing capacity increases. Furthermore, the results also prove that there is a clear proportional relation between relative densities –bearing capacity. The model test provides qualitative information on parameters influencing the bearing capacity of square footing. These tests can be used to check the bearing capacity estimated by the conventional methods.

6

Effect of randomly distributed polypropylene fiber reinforcement on the shear behavior of sandy soil

Benziane Mehdi Missoum, Della Noureddine, Denine Sidali, Sert Sedat, Nouri Said

Studia Geotechnica et Mechanica

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2019

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Vol. 41, nr 3

151--159

EN

The inclusions of geosynthetic materials (fibers, geomembranes and geotextiles) is a new improvement technique that ensures uniformity in the soil during construction. The use of tension resisting discreet inclusions like polypropylene fibers has attracted a significant amount of attention these past years in the improvement of soil performance in a cost-efficient manner. A series of direct shear box tests were conducted on unreinforced and reinforced Chlef sand with different contents of fibers (0, 0.25, 0.5 and0.75%) in order to study the mechanical behavior of sand reinforced with polypropylene fibers. Samples were prepared at three different relative densities 30%, 50% and 80% representing loose, medium dense and dense states, respectively, and performed at normal stresses of 50, 100 and 200 kPa. The experimental results show that the mechanical characteristics are improved with the addition of polypropylene fibers. The inclusion of randomly distributed fibers has a significant effect on the shear strength and dilation of sandy soil. The increase in strength is a function of fiber content, where it has been shown that the mechanical characteristics improve with the increase in fiber content up to 0.75%, this improvement is more significant at a higher normal stress and relative density.

7

Effect of Vacuum Hot-Press Process on The Sintered Characteristics and Mechanical Properties of A High-Density Cr-31.2 Mass% Ti Alloy

Chang S.-H., Li C.-L., Huang K.-T., Yang T.-H.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

1715--1723

EN

In this study, two different compositions of submicron-structured titanium (760 nm) and micron-structured chromium (4.66 μm) powders were mixed to fabricate Cr-31.2 mass% Ti alloys by vacuum hot-press sintering. The research imposed various hot-press sintering pressures (20, 35 and 50 MPa), while the sintering temperature maintained at 1250°C for 1h. The experimental results showed that the optimum parameters of the hot-press sintered Cr-31.2 mass% Ti alloys were 1250°C at 50 MPa for 1h. Also, the relative density reached 99.94%, the closed porosity decreased to 0.04% and the hardness and transverse rupture strength (TRS) values increased to 81.90 HRA and 448.53 MPa, respectively. Moreover, the electrical conductivity is enhanced to 1.58 × 104 S·cm-1 However, the grain growth generated during the high-temperature and high-pressure of the hot-press sintering process resulted in the grain coarsening phenomenon of the Cr-31.2 mass% Ti alloys after 1250°C hot-press sintering at 50 MPa for 1h. In addition, the Cr-31.2 mass% Ti alloys were fabricated with the submicron-structured titanium (760 nm) and chromium (588 nm) powders showed more effective compaction than the micron-structured titanium (760 nm) and chromium (4.66 μm) powders did. The closed porosity decreases to 0.02% and the hardness values increase to 83.23 HRA. However, the agglomeration phenomenon of the Cr phase and brittleness of the TiCr2 Laves phases easily led to a slight decrease in TRS (400.54 MPa).

8

Ocena możliwości zastosowania metody georadarowej i elektrooporowej do identyfikacji rozluźnionych stref gruntów niespoistych

Mieszkowski R., Zawrzykraj P., Żmudzin D., Wójcik E., Popielski P.

Przegląd Geologiczny

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2017

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Vol. 65, nr 10/2

779--784

EN

The results of the possibility of geophysical methods application (such as geoelectrical ones, including ground penetrating radar and electrical resistivity tomography) to identify areas of loose sands were presented in the article. Registered anomalies obtained from geophysical survey have been verified by geological and engineering tests (drillings and dynamic probing). Measurements were carried out along the part of the lateral earth dam, consisting of man-made soils with a thickness of approximately 7 m and underlying alluvial medium grained sands. The results obtained from the geophysical survey and direct assessment of density by means of dynamic probing allowed to demonstrate the relationship between a specific type of geophysical anomalies and the density of non-cohesive man-made soils.

9

Wpływ warunków ściskania z równoczesnym ściskaniem na proces zagęszczania spieków

Tkocz M., Rosiak M.

Hutnik, Wiadomości Hutnicze

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2017

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Vol. 84, nr 8

400--402

PL

Właściwości wyrobów wytwarzanych metodami metalurgii proszków zależą miedzy innymi od ich porowatości, która może być w pewnym zakresie kontrolowana w kolejnych operacjach technologicznych. W artykule przedstawiono wyniki wstępnych prób ściskania z równoczesnym skręcaniem, które przeprowadzono w celu sprawdzenia wpływu zastosowanych parametrów odkształcania na zmianę porowatości spieków wykonanych z proszku Distaloy AB. Badania wykazały, że główną rolę w procesie zagęszczania spieków w trakcie analizowanego sposobu kształtowania odgrywa zastosowany gniot, natomiast do oceny wpływu zastosowanych parametrów skręcania na porowatość spieków należy przeprowadzić obserwacje mikrostruktury.

EN

Properties of products made by powder metallurgy depend, inter alia, on their porosity that can be, to some extent, controlled in the subsequent technological operations. A series of simultaneous compression and torsion tests has been performed for Distaloy AB sintered samples in order to find out how applied deformation parameters affect the changes in samples porosity. Selected results are presented in the paper. They suggest that applied reduction in height plays the major role in densification of sinters during the analysed deformation method. However, microstructure examinations are necessary to assess an effect of the applied torsion parameters on the sinters porosity.

10

Analysis of prognosis of lowland river bed erosion based on geotechnical parameters

Smaga A.

Studia Geotechnica et Mechanica

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2015

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Vol. 37, nr 4

57--63

EN

The river erosion is a complex process, the dynamics of which is very difficult to predict. Its intensity largely depends on hydraulic conditions of the river channel. However, it is also thought that natural resistance of the subsoil has a great influence on the scale of the erosion process. Predicting the effects of this process is extremely important in the case of constructing a piling structure (for example, artificial reservoirs). The partition of the river channel causes significant lowering of the river channel bed downstream the dam which threatens the stability of hydro technical and engineering (bridges) buildings. To stop this unwanted phenomenon, stabilizing thresholds are built. However, random location of thresholds significantly reduces their effectiveness. Therefore, taking under consideration natural geotechnical conditions of the subsoil appears to be extremely important. In the light of the current development of in-situ tests in geotechnics, an attempt to use results from these tests to predict the bed erosion rate was made. The analysis includes results from CPTU and DPL tests, which were carried out in the Warta River valley downstream the Jeziorsko reservoir. In the paper, the general diagrams for the procedure of obtaining and processing the data are shown. As a result, the author presents two multidimensional bed erosion rate models built based on hydraulic data and results from CPTU or DPL tests. These models allow taking more effective actions, leading to the neutralization of the effects of the intensive bed erosion process.

11

Interpretowanie stopnia zagęszczenia gruntów niespoistych na podstawie wyników sondowań statycznych i dynamicznych

Ura M., Tarnawski M.

Przegląd Geologiczny

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2014

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Vol. 62, nr 10/2

715--720

EN

Engineering geologists have at their disposal a series of penetrometers to investigate density of non-cohesive soils. Sometimes, however, they seem to give incompatible results for similar or same soils. Some researches argue that strength and compressibility of these soils are too complex phenomena to be described solely by the single parameter of relative density and they base their findings on sophisticated tests in calibration chambers. While it might be the case, one should still start form examining correlations between numerical results of field tests from various types of penetrometers. The earlier authors' studies have produced local correlations between the results of CPT (cone tip resistance) and DPSH (number of blows) as well as between CPT and MPT (pressuremeter limit pressure). New experiments with all four continuous dynamic penetrometers: DPSH, DPH, DPM and DPL, have given encouraging results indicating possible directions of standard interpretation changes and further studies.

12

Seasonal occurrence of parasites of flounder Platichthys flesus (L.) from the Gulf of Gdańsk

Chibani M., Rokicki J.

Oceanological and Hydrobiological Studies

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2004

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Vol. 33, No. 3

17--30

EN

A total of 1509 specimens of flounder Platichthys flesus (L.) were sampled in the period from April 1998 to March 2000 from the Gulf of Gdańsk. The seasonal occurrence of all parasite species was calculated. The results indicated that some parasite species occur seasonally (Diplostomum sp., Raphidascaris acus, Dichelyne minutus, Echinorhynchus gadi and Pomphorhynchus laevis), while others do not (Trichodina borealis, Hysterothylacium aduncum, Cucullanus heterochrous). Since some parasites occurred year-round at low levels of infection, it was difficult to determine if they exhibited seasonality or not (Glugea anomala, Gyrodactylus unicopula, Diplostomum mergi, Bothriocephalus scorpii and Lampetra sp.). Gyrodactylus flesi was noted occasionally.

13

Investigation of the sintering process of compacts from copper, silver, and nickel powders mixture

Gacek S.

Metallurgy and Foundry Engineering

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2004

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Vol. 30, No 2

109-116

EN

The principal objective of the entire project was to investigate the complete course of sintering two- and three-component materials made of copper, silver, and nickel powders. Under the first task, there were made powder mixes according to predetermined chemical composition patterns, and from those mixes, sections were formed by compressing them; the sections compressed showed different relative densities of 60, 70, 80 and 90%. The individual sections were sintered at temperatures and during time periods as indicated below: CuNi sections at 1000 degrees C for: 6, 24 houres; AgNi sections at 930 degrees C for: 15, 60, 120, 240 minutes; AgCu sections at 750 degrees C, 800 degrees C for: 15, 60, 120 minutes; CuAgNi sections at 700 degrees C, 750 degrees C, 800 degrees C, 850 degrees C for: 15, 60, 120 minutes. The samples investigated were sintered in a dilatometer under the vacuum conditions or in a silite furnace in a hydrogen atmosphere. While sintering, changes in sizes, volumes, and densities occur, and their course depends on multiple factors, mainly on chemical composition, density after the compression completed, temperature, and sintering duration; the properties of the starting powders have also a significant impact on those changes. On the basis of the structure analysis, it was stated that the sintering process resulted in the formation of two- and three-component solid solutions having different degrees of non-homogeneity. The structure type of sections sintered at a given temperature changed when the sintering duration was prolonged. It was also proved that the chemical composition became homogenous within one phase and that the growth of grains took place.

PL

Zasadniczym celem pracy było badanie przebiegu spiekania w materiałach dwu- i trójskładnikowych, wykonanych z proszków miedzi, srebra i niklu. Z mieszanek proszków o założonym składzie chemicznym prasowano kształtki o gęstościach względnych 60, 70, 80 i 90%. Kształtki CuNi spiekano w temperaturze 1000 stopni C w czasie: 6, 24 godzin, AgNi spiekano w temperaturze 930 stopni C w czasie: 15, 60, 120, 240 minut, AgCu spiekano w temperaturach 750 i 800°C w czasie 15, 60, 120 minut, CuAgNi spiekano w temperaturach 700, 750, 800 i 85O stopni C w czasie 15, 30, 60, 120 minut. Kształtki spiekano w dylatometrze w próżni lub w piecu silitowym w atmosferze wodoru. Przebieg zmian wymiarów, objętości i gęstości podczas spiekania jest uzależniony od bardzo wielu czynników głównie od składu chemicznego, gęstości po prasowaniu, temperatury i czasu spiekania oraz od własności proszków wyjściowych. Na podstawie badań struktury stwierdzono, że po spiekaniu powstały roztwory stałe dwu- i trójskładnikowe, o różnym stopniu niejednorodności. Charakter struktury kształtek spiekanych w danej temperaturze zmieniał się w miarę przedłużania czasu spiekania. Stwierdzono ujednorodnienie składu chemicznego w obrębie każdej fazy oraz rozrost ziarn.