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Tytuł:
Historia zapisana w kamieniu romańskiej kolegiaty pw. św. Marcina w Opatowie
History recorded in the stones of the Romanesque collegiate church in Opatów
Autorzy:
Magiera, Janusz
Bromowicz, Jan
Powiązania:
https://bibliotekanauki.pl/articles/20206015.pdf
Data publikacji:
2023
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
okres romański
kamieniarstwo
piaskowiec dolnego triasu
piaskowiec dolnej jury
znaki apotropaiczne
Romanesque period
masonry
Lower Triassic sandstone
Lower Jurassic sandstones
apotropaic marks
Opis:
Romanesque collegiate church in Opatów (south-eastern Poland) belongs to the best-preserved Early Mediaeval edifices in Poland. Its date of origin, founder, architects and history are still unclear despite numerous investigations carried out since the beginning of the 19 th century. It is clear that local sandstones were used in the construction of the impressive church. Present investigations resulted in the inventory of the stones used as a building material: their petrography, size of blocks and strange holes and striae on some of their surfaces. Dominant sandstones have different colours: white-greyish or grey-brownish. They are built of very fine-grained, well sorted quartz with siliceous-clayey binder. All sandstone blocks have similar heights (most frequent average 34–38 cm), but different lengths. Longer (up to 62 cm) are placed in the oldest parts of the edifice, shorter (up to 48 cm) form younger fragments and might have been reused after destruction of previous undefined buildups. The sandstones represent Lower Jurassic sediments exposed currently on the slopes of the Opatówka River valley in Podole, some 5 km NE of Opatów. Only a few sherry (reddish) sandstone blocks found in various parts of the walls are probably replacements during post-Romanesque reconstructions. They represent Lower Triassic sandstone from Lipowa, 3 km NE of Opatów. Lancetoidal grooves, 5–20 cm long, and hemispherical holes of 1–4 cm in diameter are apparently of anthropogenic origin (apotropaic marks); however, their purpose is unclear. It is supposed that the grooves are traces of tool sharpening or grinding, while the holes are places where sandy or dusty material was acquired for magical or medical purposes.
Źródło:
Przegląd Geologiczny; 2023, 71, 1; 12-18
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modele zmian ściśliwości przestrzeni porowej mioceńskich skał zbiornikowych z rejonu zapadliska przedkarpackiego
Models of changes in the pore compressibility of Miocene reservoir rocks from the Carpathian Foredeep region
Autorzy:
Nowak, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/31348243.pdf
Data publikacji:
2023
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
ściśliwość porowa
porowatość
model
piaskowiec
objętość porów
pore compressibility
porosity
sandstone
pore volume
Opis:
Ściśliwość porowa skał jest jednym z istotnych parametrów wykorzystywanych w trakcie badań złóż węglowodorów. Nieprawidłowe oszacowanie tego czynnika, a co za tym idzie – porowatości pierwotnej w warunkach in situ, prowadzi do błędów w szacowaniu zasobów złóż węglowodorów. Dotychczasowe próby opisania zależności pomiędzy porowatością mierzoną w ramach rutynowych badań petrofizycznych a ściśliwością porową doprowadziły do powstania szeregu modeli umożliwiających oszacowanie współczynnika ściśliwości porowej. Niestety, w trakcie prac zaczęto zauważać, że wyniki otrzymane na podstawie modeli nie mogą zastąpić badań laboratoryjnych, a jedynie służyć jako narzędzie pomocnicze. Dodatkowo wykazano, że uzyskane rezultaty różnią się w zależności od litologii, miejsca pochodzenia próbek i ciśnień, w jakich były badane. Doprowadziło to do powstawania coraz większej liczby modeli o różnym przeznaczeniu. W artykule użyto kilku najpopularniejszych modeli służących do oceny współczynnika ściśliwości piaskowców, które próbowano dopasować do uzyskanych wyników eksperymentalnych. Obiektem badań było 20 próbek piaskowców i heterolitów z rejonu zapadliska przedkarpackiego o porowatości od kilku do dwudziestu kilku procent. Przebadano je pod kątem właściwości petrofizycznych takich jak porowatość i przepuszczalność, a także dokonano analizy petrograficznej. Następnie przeprowadzono badanie ściśliwości porowej i wykonano analizę zależności pomiędzy ściśliwością a porowatością. Po uzyskaniu wyników eksperymentalnych porównano je z wynikami otrzymanymi na podstawie modeli literaturowych. W wyniku analizy statystycznej wytypowano najlepszy z modeli, który następnie został zmodyfikowany z wykorzystaniem języka R i środowiska Posit w celu jak najlepszego dopasowania do danych laboratoryjnych. Pozwoliło to na opracowanie modelu, który w porównaniu z dostępnymi modelami pozwala z dużo większą dokładnością przewidzieć współczynnik ściśliwości porowej piaskowców i heterolitów z zapadliska przedkarpackiego.
The pore compressibility of rocks is a crucial parameters used in studying hydrocarbon deposits. Inaccurate calculations of this parameter, along with the initial porosity of reservoir rocks under geostatic pressure conditions, can result in errors when estimating the capacity and potential scale of hydrocarbon accumulation. Owing to the challenges associated with conducting these measurements and their time-consuming nature, for more than fifty years, several authors have endeavoured to describe the relationship between the initial porosity measured from the obtained cores in surface conditions and the pore compressibility. These efforts led to the development of many models that allow for the calculation of the pore compressibility coefficient using the initial porosity as a basis. Unfortunately, during the course of these studies, it became evident that the results derived from models cannot substitute laboratory tests but only serve as an auxiliary tool. In addition, the results vary depending on the lithology, and the pressures applied during testing. This has led to the creation of an increasing number of models for various purposes. In the following article, multiple well-known sandstone models were used and compared with laboratory test findings. Finally, a new model was formulated, tailored to the examined rock samples. The study focused on 20 samples of sandstones and heteroliths sourced from the Carpathian Foredeep with a porosity spectrum ranging from a few to twenty percent. The samples were tested to assess their petrophysical characteristics, including porosity and permeability alongside a petrographic analysis. Then, pore compressibility tests were conducted, and an examination of the correlation between compressibility and porosity was carried out. After obtaining the experimental data, a comparatice analysis was performed, contrasting the obtained results with those derived from existing literature models. As a result of a statistical analysis, the best model was identified and subsequently adjusted using the R language and the Posit environment to optimize its alignment with the laboratory data. This resulted in the creation of a model that, in contrast to existing models, allows for significantly enhanced accuracy in predicting the pore compressibility coefficient for selected sandstones and heteroliths originating from the Carpathian Foredeep.
Źródło:
Nafta-Gaz; 2023, 79, 10; 640-650
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphometric analysis of pebbles in verification of transport processes and interpretation of palaeoenvironment: A case study from the Ogwashi Formation (Oligocene), Niger Delta Basin, Nigeria
Autorzy:
Ogbe, Ovie B.
Osokpor, Jerry
Emelue, Chukwunomso V.
Ocheli, Azuka
Powiązania:
https://bibliotekanauki.pl/articles/2204373.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
grain morphometry
sandstone facies
bivariate plot
ternary diagram
mixed environments
Oligocene sediments
morfometria
frakcja
piaskowiec
osady
Oligocen
Opis:
The present paper discusses a palaeoenvironmental interpretation of the Oligocene Ogwashi Formation (Niger Delta Basin, Nigeria) through morphometric analysis of pebbles, a research method essentially depending on the quantitative evaluation of pebble size and shape which change during transport processes in a range of depositional environments. The relationship of bivariate and ternary-diagram plots of independent functions was determined from freshly exposed sandstone sections in quarries at Ibusa, near Asaba, Nigeria. The grain size of pebbles ranges from fine (11.00 mm) to very coarse (41.33 mm), with a mean size of 21.05 mm (coarse pebbles). A bivariate plot of the flatness index vs maximum projection sphericity index shows 37% of the pebbles to fall within a beach (marine) environment, and 33% within a fluvial environment; the remaining 30% are uncertain. The maximum projection sphericity index vs oblate-prolate index bivariate plot indicates that 47% of pebbles fall within a marine environment and 22% within a fluvial environment, while the remaining 31% are uncertain. The sphericity-form ternary diagram plot shows that the pebbles primarily comprise bladed, platy, very bladed and very platy of near-equal proportions with minor elongate and very elongate stones, which suggests that the pebbles are diverse in origin. The sphericity-form bivariate plot indicates that the pebbles are largely of disc and blade shapes with a minor number of spherical and rod shapes. The near-equal proportion of pebbles in different segments of the bivariate and ternary diagram plots, and the wide distribution of the pebble grain sizes and shapes suggest the Ogwashi Formation is composed of redeposited sediments that likely were transported and deposited in a mix of marine and fluvial settings with possible transitional environments. In other words, the pebbles can be interpreted as marine-influenced fluvial sediments in marginal-marine settings.
Źródło:
Geologos; 2023, 29, 1; 21--31
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predicting Young’s modulus of Indian coal measure rock using multiple regression and artificial neutral network
Autorzy:
Chakraborty, Sayantan
Bisai, Rohan
Roy, Rohit
Palaniappan, Sathish Kumar
Pal, Samir Kumar
Rao, Karanam Uma Maheshwar
Powiązania:
https://bibliotekanauki.pl/articles/2201429.pdf
Data publikacji:
2023
Wydawca:
Główny Instytut Górnictwa
Tematy:
sandstone
shale
multiple regression
outlier analysis
artificial neural network
piaskowiec
łupek ilasty
regresja wielokrotna
analiza odchyleń
sztuczna sieć neuronowa
Opis:
Accurate information on Young’s modulus (E) is required for simulating rock deformation in mines; on the other hand, it is very cumbersome to obtain in the laboratory and collecting drilled cores in sufficient amounts, especially in the case of soft rocks, is quite impossible. Empirical equations were deducted for - from easily determinable rock properties, and the final model was selected through different statistical strength parameter tests. The generalization of the equation was verified through the normal distribution tests of residues of the equation. R2 came to be 0.609 and was validated using an artificial neural network with an improved value of 0.73.
Źródło:
Journal of Sustainable Mining; 2023, 22, 1; 41--54
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza współczynnika ściśliwości piaskowców o zróżnicowanych parametrach petrofizycznych w zmiennych warunkach ciśnień porowych i nadkładu
Analysis of the pore volume compressibility of sandstones with different petrophysical parameters under variable pore and overburden pressure conditions
Autorzy:
Nowak, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/31348191.pdf
Data publikacji:
2022
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
ściśliwość porowa
porowatość
piaskowiec
ciśnienie porowe
ciśnienie nadkładu
objętość porów
pore compressibility
porosity
sandstone
pore pressure
overburden pressure
pore volume
Opis:
Współczynnik ściśliwości przestrzeni porowej skał ma duże znaczenie dla szacowania objętości złóż węglowodorów. Próbki przechowywane w magazynach rdzeni ulegają relaksacji (spowodowanej zmianami ciśnienia i temperatury), co prowadzi do zawyżania mierzonej wielkości współczynnika porowatości w porównaniu z rzeczywistymi warunkami złożowymi. Brak uwzględnienia tego typu zmian w szacowaniu objętości złóż węglowodorów może doprowadzić do niewłaściwych wniosków dotyczących wartości złoża. Celem publikacji jest przedstawienie wpływu ciśnień na współczynnik ściśliwości, a także znaczenia tego współczynnika w badaniach nad porowatością. Ze względu na dotychczasowy brak eksperymentalnych badań współczynnika ściśliwości w Polsce celem pracy było również wskazanie możliwych dalszych kierunków badań pozwalających na lepsze poznanie tego zagadnienia. W niniejszym artykule przedstawiono wyniki badań współczynnika ściśliwości dla próbek 14 piaskowców o dobrych parametrach petrofizycznych w różnych ciśnieniach porowych i nadkładu. Analizowane próbki reprezentują piaskowce karpackie (10 próbek) oraz piaskowce dolnej jury Niżu Polskiego (4 próbki). Dla wszystkich próbek oznaczono parametry petrofizyczne, które zostały następnie użyte do sprawdzenia, czy istnieją zależności między nimi a ściśliwością. Badania zmian przestrzeni porowej przeprowadzono na aparacie przystosowanym do pomiarów ściśliwości porowej poprzez zadawanie odpowiednich ciśnień nadkładu i ciśnienia porowego. Pomiary wykonywano dla ciśnienia porowego wynoszącego 300 psi, 1000 psi i 2000 psi przy maksymalnym ciśnieniu nadkładu 7000 psi, a jako medium wypełniającego przestrzeń porową użyto 5-procentowego roztworu NaCl. W wyniku przeprowadzonych badań uzyskano szereg danych dotyczących zmian ściśliwości przestrzeni porowej oraz wyliczono współczynnik ściśliwości Cpc. Wyniki pokazują, że porowatość przeanalizowanych próbek pod wpływem ciśnienia nadkładu zmniejsza się od jednego do kilku procent, a z opracowanych modeli zmian porowatości przy różnych ciśnieniach porowych wynika, że im mniejsza różnica między ciśnieniem nadkładu a porowym, tym mniejsza zmiana porowatości. W artykule wykazano też zależność pomiędzy porowatością a współczynnikiem ściśliwości oraz wskazano kierunek dalszych prac nad tymi zagadnieniami.
The pore volume compressibility is important for estimating the volume of hydrocarbon fields. Samples stored in the core warehouses relax (due to pressure and temperature changes), which leads to overstating the measured value of the porosity factor in comparison to the actual deposit conditions. Failure to take into account such changes in the estimation of the volume of hydrocarbon fields may lead to incorrect conclusions regarding the value of the field. The aim of the publication is to present the influence of pressures on the pore volume compressibility as well as its importance in research on porosity. Due to the lack of experimental studies of the pore volume compressibility in Poland so far, the aim of the work was also to indicate possible further directions of research allowing for a better understanding of this issue. The paper presents the results of the pore volume compressibility tests for samples of 14 sandstones with good petrophysical parameters under different pore and overburden pressures. The analyzed samples represent Carpathian sandstones and Lower Jurassic sandstones of the Polish Lowland. Petrophysical parameters were determined for all samples and then used to check the relationship between them and compressibility. The research on changes in the pore space was carried out using the apparatus adapted to the pore compressibility measurements by assigning appropriate overburden and pore pressure. Measurements were made at pore pressures of 300, 1000 and 2000 psi with a maximum overburden pressure of 7000 psi, and a 5% NaCl solution was used as the pore-filling medium. As a result of the research, a number of data on changes in the compressibility of the pore space was obtained and the compressibility factor Cpc was calculated. The results show that the porosity of the analyzed samples under the influence of the overburden pressure decreases from one to several percent. The developed models of porosity changes at different pore pressures show that the smaller the difference between the overburden pressure and the pore pressure, the smaller the change in porosity. The article shows the relationship between porosity and compressibility of the pore space and indicates the direction of further work on these issues.
Źródło:
Nafta-Gaz; 2022, 78, 7; 503-512
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the cracking mechanisms in pre-cracked sandstone under radial compression by moment tensor analysis of acoustic emissions
Autorzy:
Wang, Guozhu
Luo, Xulin
Song, Lei
Wang, Yu
Han, Mouwang
Song, Zhaocun
Wu, Linjun
Wang, Zukun
Powiązania:
https://bibliotekanauki.pl/articles/2174031.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
emisja akustyczna
mechanizm pękania
tensor momentu
piaskowiec wstępnie spękany
kompresja promieniowa
acoustic emission
cracking mechanism
moment tensor
pre-cracked sandstone
radial compression
Opis:
Rock masses, especially those with different pre-existing cracks, are prone to instability and failure under tensile loading, resulting in different degrees of engineering disasters. Therefore, to better understand the effect of pre-existing cracks with different dip angles on the tensile instability failure behaviour of rocks, the mechanism of crack initiation, propagation and coalescence in precracked sandstone under radial compression loading is investigated through numerical simulations. The temporal and spatial evolution of acoustic emission (AE) events is investigated by the moment tensor (MT), and the fracture mode of micro-cracks is determined. The results show that the pre-existing cracks weaken the specimens. The strength, crack initiation points and macro-failure modes of the specimens differ significantly depending on the dip angle of the pre-existing crack. For different dip angles of the pre-existing cracks, all the micro-cracks at the crack initiation point are tensile cracks, which are dominant during the whole loading process, and mixed cracks are mainly generated near the upper and lower loading ends after the peak stress. Of the total number of events, more than 75% are tensile cracks; approximately 15% are shear mode cracks; and the remainder consist of mixed mode cracks. The study reveals the instability and failure mechanism of pre-cracked rock, which is of great significance to ensure the long-term stability of rock mass engineering.
Źródło:
Archives of Civil Engineering; 2022, 68, 3; 447--468
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geological and palaeogeographical peculiarities of the Adamów Graben area, central Poland
Autorzy:
Widera, Marek
Dzieduszyńska, Danuta
Petera-Zganiacz, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/2204352.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
marine rocks
Oligocene clays
Oligocene pebbles
Miocene sandstone
glacial lake
periglacial involutions
fossil forest
skała morska
iły oligoceńskie
piaskowiec mioceński
jezioro polodowcowe
inwolucje peryglacjalne
Opis:
From a geological and palaeogeographical point of view, the area of the Adamów Graben in the vicinity of Turek ranks amongst the best known in central Poland, with several opencast mines located here where lignite was exploited for 57 years. These large-surface exposures provide a good opportunity for detailed geological studies of strata of Late Cretaceous to Holocene age. However, the present research focuses mainly on those deposits, forms and structures that have been most thoroughly examined and are best exposed. These are Cretaceous marls and gaizes, Paleogene ‘blue clays’ and the ‘Koźmin Gravels’, Neogene sandstones, as well as the Quaternary glacial ‘Lake Koźmin’, involutions and ‘Koźmin Las’. Some of these, e.g., the ‘Koźmin Gravels’ and ‘Koźmin Las’, are not known from other Polish territories. Furthermore, results obtained by the authors over a period of nearly 30 years also include data on palaeogeographical changes across some Cenozoic intervals, especially during the early Oligocene and late Weichselian.
Źródło:
Geologos; 2022, 28, 1; 1--17
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Piaskowiec w architekturze Poznania : formy jego deterioracji na przykładzie elewacji budynku Collegium Iuridicum
Sandstone in the architecture of Poznań : its deterioration process on the example of the Collegium Iuridicum old building facade
Autorzy:
Szczepaniak, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/2074302.pdf
Data publikacji:
2022
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
piaskowiec
deterioracja
czarne naskorupienie
dziedzictwo kulturowe
Poznań
sandstone
deterioration
black crust
cultural heritage
Opis:
The article presents various forms of deterioration in sandstone panels of the Collegium Iuridicum building in Poznań. The facade of this building is exposed to various urban and rural pollutants, which have a very significant influence on the weathering of the stone. The climatic conditions in which the test building is located and structure of the stone are also an important factors of the weathering. They can significantly accelerate the stone destruction processes. Based on the ICOMOS guidelines, deterioration forms were described and classified in macro and micro scales. For this purpose, optical, cathodoluminescence and scanning microscopy with EDS analyser were used. As a result of the research, secondary mineralization and the presence of numerous elements in the black crusts were identified. They are directly related to polluted air and the combustion of solid fuels. The identified elements include: Na, Mg, Al, Ca, P, K, S, Hg, Pb, Fe, Ti, Sc, Ni, Br, Mo, Zn, Mn, gypsum, calcite, fly ash particle.
Źródło:
Przegląd Geologiczny; 2022, 70, 2; 126--134
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on the shear creep characteristics of anchored jointed rock masses under creep fatigue loading
Autorzy:
Song, Yang
Li, Yong-Qi
Powiązania:
https://bibliotekanauki.pl/articles/2200837.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
disturbed load
sandstone
marble
creep body
rheological model
Opis:
To study creep characteristics of deep rock masses under low-frequency earthquakes and other loads, sandstone and marble samples were used to characterize soft rock and hard rock, respectively. Shear creep tests of anchored rock masses under fatigue loading were carried out by using the graded loading method. A new nonlinear rheological model was constructed to characterize mechanical properties of anchored rock masses under fatigue loading. Creep fatigue curves of soft rock and hard rock have clear creep characteristics including instantaneous, attenuation, steady-state and accelerated creep stages. This work provides new insights into the stability of rock masses.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 4; 625--635
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of deformation properties of coal measure sandstones through regression analyses and artificial neural networks
Autorzy:
Köken, Ekin
Powiązania:
https://bibliotekanauki.pl/articles/2073875.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
piaskowiec
sztuczna sieć neuronowa
deformacja
sandstone
Zonguldak
deformation properties
regression analysis
artificial neural network
Opis:
The deformation properties of rocks play a crucial role in handling most geomechanical problems. However, the determination of these properties in laboratory is costly and necessitates special equipment. Therefore, many attempts were made to estimate these properties using different techniques. In this study, various statistical and soft computing methods were employed to predict the tangential Young Modulus (Eti, GPa) and tangential Poisson’s Ratio (vti) of coal measure sandstones located in Zonguldak Hardcoal Basin (ZHB), NW Turkey. Predictive models were established based on various regression and artificial neural network (ANN) analyses, including physicomechanical, mineralogical, and textural properties of rocks. The analysis results showed that the mineralogical features such as the contents of quartz (Q, %) and lithic fragment (LF, %) and the textural features (i.e., average grain size, d50, and sorting coefficient, Sc) have remarkable impacts on deformation properties of the investigated sandstones. By comparison with these features, the mineralogical effects seem to be more effective in predicting the Eti and vti. The performance of the established models was assessed using several statistical indicators. The predicted results from the proposed models were compared to one another. It was concluded that the empirical models based on the ANN were found to be the most convenient tools for evaluating the deformational properties of the investigated sandstones.
Źródło:
Archives of Mining Sciences; 2021, 66, 4; 523--542
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bearing capacity of E-shaped footing on layered sand
Autorzy:
Nazeer, S.
Dutta, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/1818792.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
square footing
E-shaped footing
finite element analysis
bearing capacity
layered sandstone
thickness of upper layer
friction angle
stopa fundamentowa
analiza elementów skończonych
nośność podłoża
piaskowiec warstwowy
grubość warstwy wierzchniej
kąt tarcia
Opis:
Purpose: The purpose of this study is to estimate the ultimate bearing capacity of the E-shaped footing resting on two layered sand using finite element method. The solution was implemented using ABACUS software. Design/methodology/approach: The numerical study of the ultimate bearing capacity of the E-shaped footing resting on layered sand and subjected to vertical load was carried out using finite element analysis. The layered sand was having an upper layer of loose sand of thickness H and lower layer was considered as dense sand of infinite depth. The various parameters varied were the friction angle of the upper (30° to 34°) and lower (42° to 46°) layer of sand as well as the thickness (0.5B, 2B and 4B) of the upper sand layer. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to decrease with the increased in the H/B ratio for all combinations of parameters. The dimensionless ultimate bearing capacity was maximum for the upper loose sand friction angle of 34° and lower dense sand friction angle of 46°. The results further reveal that the dimensionless bearing capacity of the E-shaped footing was higher in comparison to the dimensionless bearing capacity of the square footing on layered sand (loose over dense). The improvement in the ultimate bearing capacity for the E-shaped footing was observed in the range of 109.35% to 152.24%, 0.44% to 7.63% and 0.63% to 18.97% corresponding to H/B ratio of 0.5, 2 and 4 respectively. The lowest percentage improvement in the dimensionless bearing capacity for the E-shaped footing on layered sand was 0.44 % at a H/B = 2 whereas the highest improvement was 152.24 % at a H/B = 0.5. Change of footing shape from square to E-shaped, the failure mechanism changes from general shear to local shear failure. Research limitations/implications: The results presented in this paper were based on the numerical study conducted on E-shaped footing made out of a square footing of size 1.5 m x 1.5 m. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size E-shaped footing. Practical implications: The proposed numerical study can be useful for the architects designing similar types of super structures requiring similar shaped footings. Originality/value: No numerical study on E-shaped footing resting on layered sand (loose over dense) were conducted so far. Hence, an attempt was made in this article to estimate the bearing capacity of these footings.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2021, 105, 2; 49--60
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bearing capacity of embedded and skirted E-shaped footing on layered sand
Autorzy:
Nazeer, S.
Dutta, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/2055759.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
skirted and embedded E-shaped footing
E-shaped footing
finite element analysis
bearing capacity
layered sandstone
skirt depth
embedment depth
thickness of upper layer
friction angle
stopa fundamentowa
analiza elementów skończonych
nośność podłoża
piaskowiec warstwowy
grubość warstwy wierzchniej
kąt tarcia
Opis:
Purpose: The purpose of this study is to investigate the ultimate bearing capacity of the embedded and skirted E-shaped footing resting on two layered sand using finite element method. The analysis was carried out by using ABACUS software. Design/methodology/approach: The numerical study of the ultimate bearing capacity of the embedded and skirted E-shaped footing resting on layered sand and subjected to vertical load was carried out using finite element analysis. The layered sand was having an upper layer of loose sand of thickness H and lower layer was considered as dense sand of infinite depth. The various parameters varied were the friction angle of the upper (30° to 34°) and lower (42° to 46°) layer of sand, the skirt depth (0B, 0.25B, 0.5B and 1B), the embedment depth (0B, 0.25B, 0.5B and 1B) and the thickness (0.5B, 2B and 4B) of the upper sand layer, where B is the width of the square footing. Findings: The ultimate bearing capacity was higher for the skirted E-shaped footing followed by embedded E-shaped footing and unskirted E-shaped footing in this order for all combinations of variables studied. The improvement in the ultimate bearing capacity for the skirted E-shaped footing in comparison to the embedded E-shaped footing was in the range of 0.31 % to 61.13 %, 30.5 % to 146.31 % and 73.26 % to 282.38% corresponding to H/B ratios of 0.5, 2.0 and 4.0 respectively. The highest increase (283.38 %) was observed at φ1 =30° and φ2 =46° corresponding to H/B and Ds/B ratio of 4.0 and 1.0 respectively while the increase was lowest (0.31 %) at φ1 =34° and φ2 =46° at H/B ratio of 0.5 and Ds/B ratio of 0.5. For the skirted E-shaped footing, the lateral spread was more as in comparison to the embedded E-shaped footing. The bearing capacity of the skirted footing was equal the sum of bearing capacity of the surface footing, the skin resistance developed around the skirt surfaces and tip resistance of the skirt with coefficient of determination as 0.8739. The highest displacement was found below the unskirted and embedded E-shaped footing, and at the skirt tip in the case of the skirted E-shaped footing. Further, the displacement contours generated supports the observations of the multi-edge embedded and skirted footings regarding the ultimate bearing capacity on layered sands. Research limitations/implications: The results presented in this paper were based on the numerical study conducted on E shaped footing made from a square footing of size 1.5 m x 1.5 m. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size E shaped footing. Practical implications: The proposed numerical study can be an advantage for the architects designing similar types of super structures requiring similar shaped footings. Originality/value: No numerical study on embedded and skirted E shaped footing resting on layered sand (loose over dense) were conducted so far. Hence, an attempt was made in this article to estimate the bearing capacity of the same footings.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2021, 108, 1; 5--23
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enigmatic clusters of sandstone boulders on plateaus of the Stołowe Mountains (Sudetes, south-west Poland) – their geoheritage and geotouristic value
Autorzy:
Migoń, Piotr
Parzóch, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2204359.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
sandstone landforms
tablelands
escarpment retreat
geo-interpretation
ukształtowanie terenu
piaskowiec
skarpa
geointerpretacja
Opis:
Among sites of geomorphological interest in the tableland of the Stołowe Mountains, consisting of clastic sedimentary rocks of Late Cretaceous age, are enigmatic occurrences and clusters of sandstone boulders within plateau levels that are underlain by mudstones and marls. These boulders are allochthonous, having been derived from the quartz sandstone beds that support the upper plateau level and stratigraphically are in excess of 50 m above the altitudinal position of the boulders. Topographic conditions preclude long-distance transport from the escarpment slopes; boulders are hypothesised to be the last remnants of completely degraded outliers (mesas) of the upper plateau. Their present-day altitudinal position is explained by passive ‘settling’ following disintegration of caprock and denudation of the underlying weaker rocks. Two localities are here presented in detail, Łężyckie Skałki and Pustelnik, along with adjacent boulder trains in the valleys incised into the plateau. It is argued that both localities have considerable geoheritage value and both play the role of geosites, although on-site facilities are so far limited. However, the complex history of boulders sets a series of challenges for successful geo-interpretation.
Źródło:
Geologos; 2021, 27, 3; 141--155
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kamień podkrakowskich budowli romańskich
Building stones used in Romansque edifices in the vicinity of Kraków
Autorzy:
Bromowicz, Jan
Magiera, Janusz
Powiązania:
https://bibliotekanauki.pl/articles/2076212.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
okres romański
kamieniarstwo
piaskowiec istebniański
Romanesque period
masonry
Istebna sandstone
Upper Jurassic limestone
Opis:
Three objects were studied within a project aimed at investigation of stones used in the Romanesque edifices in the vicinity of Kraków, and continued since 2019. These are the churches in Dziekanowice (21 km SE of Kraków) and in Czchów (58 km SE of Kraków), and a clergy house in Morawica (13 W of the Kraków city centre). The church in Dziekanowice is relatively completely and well preserved, while the only Romanesque remnants of the church in Czchów are those reused in the Gothic church. It is a clergy house in Morawica (a former castle), whose walls contain Romanesque fragments. Two former edifices are built of the Istebna sandstone (Upper Cretaceous-Paleogene), quarried from the local flysch bedrock. Fine-grained, grey-yellowish stone dominates. It is soft and easily workable due to argillaceous binder (matrix). The stone blocks are precisely shaped and well fitted. Romanesque remnants of the clergy house in Morawica are con- structed predominantly of limestone, also of local origin. Only a fragment of the NW wall is built of the Istebna sandstone. This fragment is probably a part of the butress supporting the NW wall. The study shows that stonemasons and builders of that time had good skills of selecting and applying proper stone blocks for particular purposes. Blocks used in load-bearing structures were exceptionally well shaped and fitted. On the other hand, those skills varied. The frieze from the Romanesque church in Czchów is rather primitive. The size of limestone blocks used in the clergy house in Morawica is strikingly similar to those of various Romanesque edifices in Kraków. It seems, therefore, that those blocks could have been quarried and shaped in quarries located in the city, where the masonry “industry” was well developed. Larger, irregular blocks, used as foundations and filler in the “opus emplectum” type walls were probably quarried on site. Moreover, stones used in more eminent edifices (churches, castles) were probably more carefully selected. The Morawica castle (clergy house) and many churches in Kraków were built of limestone blocks without cherts.
Źródło:
Przegląd Geologiczny; 2021, 69, 2; 103--108
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena przydatności wykorzystania geometrycznych parametrów przestrzeni porowej z obrazów tomograficznych w kontekście pomiarów NMR, porozymetrii rtęciowej i porozymetrii helowej
The study of application of geometric parameters of the pore space from tomographic images in the context of NMR measurements, mercury porosimetry and helium porosimetry
Autorzy:
Drabik, Katarzyna
Krakowska-Madejska, Paulina
Puskarczyk, Edyta
Dohnalik, Marek
Powiązania:
https://bibliotekanauki.pl/articles/2143418.pdf
Data publikacji:
2021
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
tomografia komputerowa
czerwony spągowiec
NMR
porozymetria
poROSE
computed X-ray tomography
Permian Rotliegend Sandstone
mercury porosimetry
Opis:
Głównym celem pracy była ocena przydatności wyników interpretacji ilościowej, uzyskanej z obrazowania wewnętrznej struktury próbek skał z wykorzystaniem metody tomografii komputerowej, do szacowania parametrów zbiornikowych takich jak porowatość czy przepuszczalność. W pracy badano zależności korelacyjne pomiędzy parametrami przestrzeni porowej uzyskanymi z analizy obrazów tomografii komputerowej a wynikami standardowych badań laboratoryjnych. Materiał badawczy składał się z próbek piaskowców czerwonego spągowca, facji eolicznej, pobranych z obszaru Niżu Polskiego. Do analiz wybrano kilkadziesiąt próbek skał piaskowców czerwonego spągowca, dla których policzono 69 parametrów. Interpretacja jakościowa i ilościowa polegała na porównaniu parametrów otrzymanych z analizy obrazu tomograficznego z wcześniej uzyskanymi wynikami analiz laboratoryjnych obejmujących następujące metody badawcze: porozymetrię helową (Por.He), spektrometrię jądrowego rezonansu magnetycznego (NMR), porozymetrię rtęciową (Por.Hg) i przepuszczalność absolutną (przepuszcz). Utworzono macierze korelacji dla wszystkich dostępnych parametrów, do pracy wybrano korelacje istotne, o najwyższym współczynniku korelacji liniowej. Zaobserwowano istotne zależności liniowe pomiędzy parametrami wyznaczonymi z analizy obrazów CT i innych metod badawczych. Uzyskano modele pozwalające na szacowanie przepuszczalności, porowatości i zawartości wody nieredukowalnej na podstawie parametrów geometrycznych otrzymanych z obrazów tomograficznych (współczynnik kształtu, charakterystyka Eulera czy powierzchnia właściwa). W efekcie możliwe jest wstępne oszacowanie parametrów petrofizycznych jedynie na bazie wyników z nieniszczącej metody CT. W przypadku obrazowania tomograficznego pełnych rdzeni uzyskane związki pozwalają na wstępną estymację rozkładu porowatości i gęstości objętościowej w całym rdzeniu, co może być pomocne podczas typowania miejsc do poboru próbek rdzeni przeznaczonych do szczegółowych badań laboratoryjnych.
The main purpose of the study was to assess the usefulness of the results of quantitative interpretation of computed tomography (CT) images of rocks’ pore structure for the estimation of reservoir parameters, such as porosity and permeability. This study presents results of correlation analyses between the pore space parameters obtained from the analysis of computed tomography images and the results of standard laboratory tests. The research material consisted of samples representing Rotliegend sandstones of aeolian facies, collected from core material from wells located in the Fore-Sudetic Monocline. Several dozen samples were selected for analysis, for which 69 parameters were calculated. The qualitative and quantitative interpretation consisted in comparing the parameters obtained from the analysis of the tomographic images with the previously obtained results of laboratory analyzes including the following research methods: helium porosimetry (Por.He), nuclear magnetic resonance spectrometry (NMR), mercury porosimetry (Por.Hg) and absolute permeability (let it pass). Correlation matrices for all available parameters were determined, significant correlations with the highest coefficient of linear correlation were selected as a subject of this work. Significant linear relationships were observed between the parameters determined from the analysis of CT images and other research methods. Models that were obtained allowed to estimate the permeability, porosity, and irreducible water content based on geometrical parameters obtained from tomographic images (shape factor, Euler characteristic or specific surface area). The important result of this work is the possibility to estimate petrophysical parameters based on the results of the non-destructive CT method only. In the case of tomographic imaging of whole cores, the obtained results allow for a preliminary estimation of the porosity and volume density distribution in the entire core, which may be helpful in selecting representative samples of core for detailed laboratory tests.
Źródło:
Nafta-Gaz; 2021, 77, 11; 725-735
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 95

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