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1

Modele zmian ściśliwości przestrzeni porowej mioceńskich skał zbiornikowych z rejonu zapadliska przedkarpackiego

Nowak Krzysztof

Nafta-Gaz

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2023

|

R. 79, nr 10

640--650

PL

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.

EN

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.

2

Predicting Young’s modulus of Indian coal measure rock using multiple regression and artificial neutral network

Chakraborty Sayantan, Bisai Rohan, Roy Rohit, Palaniappan Sathish Kumar, Pal Samir Kumar, Rao Karanam Uma Maheshwar

Journal of Sustainable Mining

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2023

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Vol. 22, iss. 1

41--54

EN

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.

3

Shear strength characteristics of weathered jointed Kenny Hill interbedded formation for cylindrical specimen under direct shear test

Abbas Hasan Ali, Mohamed Zainab, Taher Muntadher J., Kudus Sakhiah Abdul, Salman Manaf Raid, Ghaltan Hasanain Muhammad

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 2

1--12

EN

The sliding failures commonly occur in interbedded formations along the weakness plane of the bedding plane a sedimentary rock or the joint interface. Therefore, studying the shear strength characteristics at the bedding plane or interface is crucial for evaluating the expected failure plane. In this study, the shear strength characteristics of planar jointed Kenny Hill shale, sandstone, and shale-sandstone specimens were investigated using the direct shear box method. The results reveal that the friction angle values for the planar sandstone, shale-sandstone, and shale are 31.28°, 21.1°, and 19.34°, respectively. These findings, combined with the shear stress-strain behavior, suggest that the interface (shale-sandstone) is primarily influenced by the shale characteristics rather than the sandstone characteristics. Hence, it is important to consider failure along the interface when analyzing critical conditions, particularly in slope failure scenarios.

4

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

Ogbe Ovie B., Osokpor Jerry, Emelue Chukwunomso V., Ocheli Azuka

Geologos

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2023

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Vol. 29, No. 1

21--31

EN

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.

5

Piaskowiec w architekturze Poznania : formy jego deterioracji na przykładzie elewacji budynku Collegium Iuridicum

Szczepaniak Małgorzata

Przegląd Geologiczny

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2022

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Vol. 70, nr 2

126--134

EN

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.

6

Analiza współczynnika ściśliwości piaskowców o zróżnicowanych parametrach petrofizycznych w zmiennych warunkach ciśnień porowych i nadkładu

Nowak Krzysztof

Nafta-Gaz

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2022

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R. 78, nr 7

503--512

PL

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.

EN

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.

7

Experimental study on fatigue mechanical properties of sandstone after dry and wet cycle

Jin-Song Zhang, Yu Lu, Heng-Liang Zhang, Yu-Di Yang, Yi-Shun Bu

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

377--387

EN

At present, many studies have been carried out on the fatigue mechanical properties of conventional rocks, but there are few studies on the mechanical properties of rocks after water rock interaction. The aim is to better study the fatigue mechanical characteristics of sandstone after dry wet cycle and the research object we take was sandstone samples after a certain number of drying and wetting cycles. The WAW-2000 electro-hydraulic servo pressure system was used to carry out uniaxial fatigue cyclic loading and unloading tests with different amplitudes and different upper limit stresses. The test found that: when the sample is damaged under fatigue load, the stress-strain curve shows a sharp downward trend and a sudden instability failure occurred in the sample. With the increase of the upper limit stress and amplitude, the life of the sample decreases gradually which also conforms to the change of power function. Then the relationship between fatigue life and stress is obtained. The fatigue stress-strain curve is characterized by sparse-dense-sparse. With the increase of cycle time, the axial strain of the sample shows an inverted “S” shape. The strain change can be divided into three stages: initial stage, constant velocity stage and acceleration stage.

8

Shear rupture behaviors of intact and granulated Wombeyan marble with the flat-jointed model

Li Kaihui, Han Dongha, Fan Xiang, Yang Yi, Wang Fei

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e51, 2022

EN

Many large hydropower projects have been constructed in the highly interlocked and non-persistently jointed rock mass (e.g., the columnar jointed basalt). Regarding the granulated Wombeyan marble as an analog of such rock mass, a series of direct shear test simulations under constant normal loading (CNL) and constant normal stiffness (CNS) boundary conditions were performed to better understand its shear rupture behavior using the flat-jointed model based on the discrete element method. The results show that the shear process under the CNS condition can be divided into four stages: linear-elastic stage, yielding stage, shear wear stage and shear sliding stage. The strain-strengthening in the shear wear stage is evident due to the feedback normal stress provided by the cap induced by shear dilation. As the initial applied normal stress increases, the peak shear strength point of specimens under CNL approaches the yield point of specimens under CNS. Additionally, the shear rupture process under CNS is strain controlled in granulated specimens but stress controlled in intact specimens. Correspondingly, the shear rupture zone creation in granulated specimens is not but that in intact specimens is dependent on the initial applied normal stress. Finally, it is demonstrated that the CNS condition can improve the stability of rock slopes or underground excavations embedded in such rock mass and its improvement effect increases with the normal stiffness.

9

Changes of physical properties of thermal damaged sandstone with time lapse

Wang Zuoquan, Zhang Weiqiang, Shi Zhoujian, Zhang Shaoteng

Acta Geophysica

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2022

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Vol. 70, no 3

1193--1202

EN

Understanding the change of physical properties of thermal damaged rock with time lapse in high temperature engineering plays an important role in the prediction of engineering life and the prevention of engineering disasters. In order to study the effect of time lapse on the physical properties of heat damaged sandstone, the sandstone was heated to the target temperature and cooled, and its resistivity, Leeb hardness, volume and mass were measured. The values of these parameters should be measured again after placing the thermally damaged sandstone for 3, 6 and 9 months. The results show that, after being placed for 3 months, the quality of heat damaged sandstone increased at all test temperatures. At 200 °C, 400 °C, 600 °C and 900 °C, the resistivity of heat damaged sandstone decreases, and there is no obvious change in Leeb hardness and volume. At 800 °C, the resistivity of thermally damaged sandstone increases, the Leeb hardness decreases and the volume increases. After being placed for 6 months, the resistivity, Leeb hardness and volume of thermally damaged sandstone did not change at all test temperatures, but the mass of thermally damaged sandstone increased at 800 °C and 900 °C. After being placed for 9 months, the resistivity, Leeb hardness, volume and mass have no obvious change at all test temperatures.

10

Renowacja i konserwacja kamiennej płyty z tropami dinozaurów w rezerwacie przyrody Gagaty Sołtykowskie

Rembiś Marek, Dźwigulska-Musiał Paula

Przegląd Geologiczny

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2021

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Vol. 69, nr 2

91--96

EN

The inanimate nature reserve Gagaty Sołtykowskie is located in the northern part of the Permian-Mesozoic margin of the Holy Cross Mountains, within the abandoned Odrowąż quarry. Trackways of dinosaurs have been printed on a sandstone bedding plane within the Lower Jurassic (Hettangian) Zagaje Formation. The tracks are the oldest known evidence of a group life of the herbivore (plant-eating) sauropods andofa hunting group of predatory the ropods. After twenty years of being exposed to visitors, the sandstone layer had to be thoroughly renovated and conserved. On the basis of an evaluation of its state of preservation followed by laboratory examinations, the authors have prepared the program of conservation procedures and established a set of appropriate materials. The surface of the layer has been cleaned and its loose fragments fixed with the Injektionharz 100 (Remmers) glue. The layer has been impregnated and fractures sealed with an organosilicon compound KSE 100 and KSE 300 (Remmers). The tracks of dinosaurs have become more vivid due to their saturation with the mixture of the KSE 300 and a mineral pigment.

11

Enigmatic clusters of sandstone boulders on plateaus of the Stołowe Mountains (Sudetes, south-west Poland) – their geoheritage and geotouristic value

Migoń Piotr, Parzóch Krzysztof

Geologos

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2021

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Vol. 27, No. 3

141--155

EN

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.

12

Assessment of deformation properties of coal measure sandstones through regression analyses and artificial neural networks

Köken Ekin

Archives of Mining Sciences

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2021

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Vol. 66, no. 4

523--542

EN

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.

13

Artificial intelligence-based modeling for the estimation of Q-Factor and elastic young’s modulus of sandstones deteriorated by a wetting-drying cyclic process

Rashid Hafiz Muhammad Awais, Ghazzali Muhammad, Waqas Umer, Malik Adnan Anwar, Abubakar Muhammad Zubair

Archives of Mining Sciences

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2021

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Vol. 66, no. 4

635--658

EN

In this study, a series of destructive and non-destructive tests were performed on sandstone samples subjected to wetting-drying cycles. A total of 25 Wet-Dry cycles were provided to investigate any significant change in the engineering properties of sandstones in terms of their porosity, permeability, water absorption, density, Q-factor, elastic modulus (E), and unconfined compressive strength (UCS). The overall reduction in the values of density, E, Q-factor, and UCS was noted as 3-4%, 42-71%, 34-62%, and 26-70% respectively. Whereas, the overall appreciation in the values of porosity, permeability, and water absorption was recorded as 24-50%, 31-64%, and 25-50% respectively. The bivariate analysis showed that the physical parameters had a strong relationship with one another and their Pearson’s correlation value (R) ranged from 0.87-0.99. In prediction modeling, Q-factor and E were regressed with the contemplated physical properties. The linear regression models did not provide satisfactory results due to their multicollinearity problem. Their VIF (variance inflation factor) value was found much greater than the threshold limit of 10. To overcome this problem, the cascade-forward neural network technique was used to develop significant prediction models. In the case of a neural network modeling, the goodness of fit between estimated and predicted values of the Q-factor (R2 = 0.86) and E (R2 = 0.91) was found much better than those calculated for the Q-factor (R2 = 0.30) and E (R2 = 0.36) in the regression analysis.

14

Not simply volcanoes – the geoheritage of the Cretaceous system in the Land of the Extinct Volcanoes Geopark, West Sudetes (SW Poland)

Migoń Piotr, Pijet-Migoń Edyta

Geotourism / Geoturystyka

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2020

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nr 1-2 (60-61)

3--22

EN

Volcanic geoheritage is emphasized as the main asset and distinctive characteristic of the Land of Extinct Volcanoes Geopark in the West Sudetes (SW Poland). However, the geoheritage values of the region are not limited to the legacy of ancient volcanism but include various other elements. This paper explores the contribution of geosites that expose sedimentary rocks of Cretaceous age and landforms developed upon these rocks. Six localities from the Geopark area, included in the comprehensive regional inventory of geosites, are presented. They represent natural and man-made sandstone outcrops and show, among others, lithological variations, small- and large-scale post-sedimentary deformation structures, landforms arising from differential weathering (rock shelters, honeycombs), boulder fields and a sandstone xenolith in volcanic rocks. Next, five localities from outside the Geopark, but still within the Pogórze Kaczawskie region, are described. Qualitative and quantitative evaluation of both groups is attempted, and the results show that, in general, geosites within the Geopark rank higher. However at least two from the other group also have significant geotourist potential. Finally, a brief comparative analysis with other parts of the Sudetes, where Cretaceous sedimentary rocks occur, is offered.

PL

Dawny wulkanizm jest uznawany za główny walor i wyróżniającą się cechę Geoparku Kraina Wygasłych Wulkanów w Sudetach Zachodnich, jednak dziedzictwo Ziemi w regionie nie ogranicza się do reliktów aktywności wulkanicznej i zawiera różne inne elementy. W tym artykule są zaprezentowane miejsca (geostanowiska), w których można oglądać naturalne i sztuczne odsłonięcia skał osadowych wieku kredowego i formy rzeźby zbudowane z tych skał. Sześć z nich jest zlokalizowanych na obszarze Geoparku i zostały one uwzględnione w regionalnej inwentaryzacji obiektów dziedzictwa Ziemi. Zagadnienia, które można omówić na przykładzie tych miejsc, obejmują między innymi zróżnicowanie litologiczne, postsedymentacyjne struktury deformacyjne w małej i dużej skali, formy będące efektem zróżnicowanego wietrzenia (schroniska podskalne, „plastry miodu”), pokrywy blokowe i ksenolit piaskowca w skałach wulkanicznych. W dalszej części opisano pięć stanowisk spoza Geoparku, z pozostałej części regionu Pogórza Kaczawskiego. Rezultaty jakościowej i ilościowej oceny stanowisk z obu grup pokazują, że obiekty położone w Geoparku mają większą wartość, ale przynajmniej dwa z drugiej grupy mają istotny potencjał geoturystyczny. W części końcowej zostało przedstawione krótkie porównanie z innymi fragmentami Sudetów, gdzie występują skały wieku kredowego.

15

Report on laboratory tests of sandstone and porphyry for rock fracture analysis

Gontarz Jakub, Szulej Jacek

Budownictwo i Architektura

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2020

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Vol. 19, no 2

87--100

EN

The paper presents the results of mechanical tests of three types of rocks from stone mines in Poland. Compression tests of cubic samples, three-point bending tests of beams, bending of beams with notch and testing of tensile strength using the quasi-Brazilian method were performed. Based on the tests, the compressive strength, tensile strength, Young's modulus, and Poisson's ratios were determined. The stress intensity factor and critical strain energy release rate in mode I were determined from the bending test of the notched beams. The determined values were used as parameters of computer models which are used to verify the authors’ method of predicting the crack propagation in the Abaqus FEA system.

PL

Artykuł prezentuje wyniki badań laboratoryjnych trzech typów skał z kopalni kamienia w Polsce. Wykonano badanie ściskania kostek, badanie trójpunktowego zginania belek, zginania belek z nacięciem i badanie rozciągania przy rozłupywaniu metodą kwazi-Brazylijską. Na podstawie badań uzyskano wytrzymałość na ściskanie, wytrzymałość na rozciąganie, moduł Younga i współczynnik Poissona. Współczynnik intensywności naprężenia i krytyczna energia pękania w modzie I zostały uzyskane z badań zginania belek z nacięciem. Uzyskane wyniki zostały użyte jako parametry do modeli komputerowych, które są używane do weryfikacji autorskiej metody przewidywania propagacji szczeliny w systemie Abaqus.

16

Petrographic, mineralogical, and climatic analyses, and risk maps for conservation strategies

Bartz Wojciech, Kościuk Jacek, Gąsior Maria, Dziedzic Teresa

Architectus

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2020

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Nr 2 (62)

135--149

EN

El Fuerte de Samaipata is a pre-Hispanic archaeological site in Bolivia that has been on the UNESCO World Heritage List. Its main part – the rock – is densely covered with a complex arrangement of terraces, platforms, water reservoirs, channels, and petroglyphs. The rapidly progressing erosion of the rock is making the petroglyphs less and less clear, and some are no longer recognisable. The main topic of this study is to indicate all risk factors conducive to erosion and to create risk maps identifying the most vulnerable areas that require immediate conservation intervention. Parallel mineralogical and petrographic studies show that the Samaipata rock is a quartz-rich, porous, well-sorted sandstone, classified as quartz arenite or subarcosic arenite. The cement of the rock is composed of quartz overgrowth and ubiquitous, pore-filling hematite-clay aggregates containing non-expanding kaolinite, illite, and expanding smectite. The rock exhibits different stages of weathering, from relatively fresh to strongly altered and heavily cracked. In comparison to fresh rock, the latter has cement enriched in clay minerals and is depleted in hematite due to weathering and the dissolution of the iron-bearing phase.

PL

El Fuerte de Samaipata to wpisane na Listę Światowego Dziedzictwa UNESCO prehiszpańskie stanowisko archeologiczne w Boliwii. Jego główna część to skała ze złożonym układem tarasów, platform, zbiorników wodnych, kanałów i petroglifów. Szybko postępująca erozja sprawia, że petroglify stają się coraz mniej wyraźne, a niektóre nie są już rozpoznawalne. Głównym tematem badań jest wskazanie wszystkich czynników ryzyka sprzyjających erozji oraz stworzenie map ryzyka identyfikujących najbardziej wrażliwe obszary wymagające natychmiastowej interwencji konserwatorskiej. Badania mineralogiczne i petrograficzne wskazują, że Samaipata to bogaty w kwarc, porowaty, dobrze posortowany piaskowiec, sklasyfikowany jako arenit kwarcowy lub arenit subarkozowy. Spoiwo składa się z przerostu kwarcu i wszechobecnych, wypełniających pory agregatów hematytowo-gliniastych zawierających nierozprężający się kaolinit, illit i rozszerzający się smektyt. Skała wykazuje różne etapy wietrzenia, od stosunkowo świeżego do mocno zmienionego i mocno spękanego. W porównaniu ze świeżą skałą ta ostatnia ma cement wzbogacony w minerały ilaste i jest zubożona w hematyt z powodu wietrzenia i rozpuszczenia fazy żelazonośnej.

17

Susceptibility of selected aggregates from sedimentary rocks to alkali-aggregate reaction

Glinicki Michał A., Jóźwiak-Niedźwiedzka Daria, Antolik Aneta, Dziedzic Kinga, Gibas Karolina

Roads and Bridges - Drogi i Mosty

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2019

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Vol. 18, no. 1

5--24

PL

W pracy przedstawiono wyniki badań reaktywności krajowych kruszyw z wybranych, litych skał osadowych przy wykorzystaniu nowych metod badawczych wdrożonych w dokumentach technicznych Generalnej Dyrekcji Dróg Krajowych i Autostrad (GDDKiA), zgodnych z metodami RILEM i ASTM. Zakres badań obejmował kruszywa grube łamane o potencjalnej przydatności do wykonania wytrzymałego i trwałego betonu, wyprodukowane ze skał wapienia, dolomitu, piaskowca i szarogłazu. W składzie mineralnym kruszyw z wapieni i dolomitu nie stwierdzono obecności reaktywnych form kwarcu; w ziarnach kruszywa z szarogłazów i piaskowca występował kwarc mikro- i kryptokrystaliczny. Na podstawie wydłużenia próbek określono następujące kategorie reaktywności wybranych krajowych kruszyw ze skał osadowych: R0, R1 i R2. Zaobserwowano występowanie żelu krzemianu sodowo-potasowo-wapniowego o składzie charakterystycznym dla produktów reakcji alkalia-kruszywo, zgodnym z danymi literaturowymi. Uzyskano spójną ocenę reaktywności kruszyw.

EN

The paper presents the results of investigations into the reactivity of domestic aggregates produced from selected sedimentary rocks, carried out using the new testing methods, consistent with the RILEM and ASTM methods, implemented by GDDKiA (Polish General Directorate for National Roads and Motorways) documents. The range of the investigations covered coarse crushed aggregates produced from limestone, dolomite, sandstone and greywacke rocks, potentially suitable for making strong and durable concrete. No reactive forms of quartz were found in the mineralogical composition of the limestone aggregates and the dolomite aggregates. Micro- and cryptocrystalline quartz occurred in the particles of the greywacke aggregates and the sandstone aggregates. On the basis of the expansion of mortar and concrete specimens the aggregates produced from the sedimentary rocks were classified into the reactivity categories: R0, R1 and R2. A sodium-potassium-calcium silicate gel, whose composition (consistent with that reported in the literature) was characteristic of the alkali-silica reaction products, was found. The investigations resulted in a consistent assessment of the reactivity of the aggregates.

18

Warunki temperaturowe w czasie diagenezy piaskowców pensylwanu w rejonie Morza Bałtyckiego

Kozłowska Aleksandra

Przegląd Geologiczny

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2019

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Vol. 67, nr 3

167--168

EN

The purpose of this study is to reconstruct the temperature conditions in the sediment during the diagenesis history of Pennsylvanian sandstones drilled in three deep boreholes in the Baltic Sea. These sandstones are represented by quartz and sublithic arenites and wackes, cemented by matrix and autigenic minerals. Among the autigenic minerals: quartz, clay minerals (kaolinite, dickite, illite) and carbonates (calcite, dolomite, ankerite) are the temperature indicators. The presence of dickite in the sediments indicates a temperature of about 120°C. Quartz and carbonate crystallization temperatures, based on the analysis of fluid inclusions, are estimated to be in the range of 70-180°C. The K/Ar age of the fibrous illite thatforms at the final stage of diagenesis (above 100° C), was determined at 262 ±2 to 247 ±4 My, i.e. from the Middle Permian to the Early Triassic. It determines a length of the post-deposition period, when the deposits were permeable for pore fluids.

19

Effects of initial damage on time-dependent behavior of sandstone in uniaxial compressive creep test

Hou Rongbin, Zhang Kai, Tao Jing

Archives of Mining Sciences

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2019

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Vol. 64, no. 4

687--707

EN

Time-dependent behavior of rock mass is important for long-term stability analysis in rock engineering. Extensive studies have been carried out on the creep properties and rheological models for variable kinds of rocks, however, the effects of initial damage state on the time-dependent behavior of rock has not yet been taken into consideration. In the present study, the authors proposed a creep test scheme with controlled initial damage to investigate the influence of initial damage on the time-dependent behavior of sandstone. In the test scheme, the initial states of damage were first determined via unloading the specimen from various stresses. Then, the creep test was conducted under different stress levels with specific initial damage. The experimental results show that there is a stress threshold for the initial damage to influence the behavior of the rock in the uniaxial compressive creep tests, which is the stress threshold of dilatancy of rock. When the creep stress is less than the stress threshold, the effect of the initial damage seems to be insignificant. However, if the creep stress is higher than the stress threshold, the initial damage has an important influence on the time-dependent deformation, especially the lateral and volumetric deformation. Moreover, the initial damage also has great influence on the creep failure stress and long-term strength, i.e., higher initial damage leading to lower creep failure stress and long-term strength. The experimental results can provide valuable data for the construction of a creep damage model and long-term stability analysis for rock engineering.

PL

Przebieg czasowy zachowania górotworu jest zagadnieniem kluczowym w analizie stabilności systemu w ujęciu długoterminowym. Przeprowadzono szerokie badania modeli reologicznych i właściwości procesów pełzania dla rozmaitych typów skał; jednakże w badaniach nie uwzględniano wpływu uszkodzeń początkowych na zachowanie górotworu i jego przebieg czasowy. W artykule autorzy zaproponowali nowy sposób przeprowadzania próby pełzania, z uwzględnieniem kontrolowanych uszkodzeń początkowych, tak by wpływ obecności uszkodzeń początkowych na przebieg czasowy zmian zachowania piaskowca mógł zostać uwzględniony. W metodzie tej w pierwszej fazie określono zakres początkowych uszkodzeń poprzez odprężenie próbki w celu wyeliminowania rożnego rodzaju naprężeń. Następnie przeprowadzono próbę pełzania w warunkach zmiennych obciążeń przykładanych do próbki o określonym poziomie uszkodzeń początkowych. Wyniki eksperymentu wskazują na istnienie pewnej wartości progowej naprężenia powyżej której obecność uszkodzeń początkowych będzie mieć wpływ na zachowanie próbki skalnej w trakcie próby jednoosiowego pełzania; jest to poziom progowy dla powstawania dylatacji. Gdy naprężenie pełzania ma wartość niższą od wartości progowej, wpływ uszkodzeń początkowych wydaje się nieznaczny. Jednakże, dla naprężeń pełzania powyżej wartości progowej, wpływ uszkodzeń początkowych na przebieg odkształceń jest znaczący, zwłaszcza w odniesieniu do odkształceń poprzecznych i objętościowych. Ponadto, istnie-nie uszkodzeń początkowych ma także wpływ na poziom naprężeń rozrywających przy próbie pełzania i wytrzymałość próbki w ujęciu długoterminowym. Wykazano, że im większe uszkodzenia początkowe, tym niższa wartość naprężenia zrywającego przy próbie pełzania i niższa wytrzymałość długoterminowa. Wyniki eksperymentu dostarczyć mogą cennych danych niezbędnych do skonstruowania modelu uszkodzeń skał wskutek pełzania oraz do analiz stabilności konstrukcji inżynierskich w ujęciu długoterminowym.

20

Experimental study on uniaxial mechanical properties and crack propagation in sandstone containing a single oval cavity

Huang Y. H., Yang S. Q., Hall M. R., Tian W. L., Yin P. F.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1359--1373

EN

The geometry and orientation of cavities in a rock mass has a significant influence on the failure mechanism and fracture propagation. The theoretical study of these behaviors is of great importance to enable fundamental understanding of unstable failure in rock mechanics. A very limited number of experimental studies have been conducted for sandstone specimens containing oval cavities. Sensitive parameters include the short axis (b) to long axis (a) ratio. Here, we enhance the present understanding of crack coalescence behavior around an oval cavity by applying uniaxial compression tests to sandstone cores containing manually inserted single oval cavity, combined with photographic and acoustic emission monitoring. The b:a ratio was varied from 1/4 to 1/1, thus the cross-sectional cavity shape evolved from oval to a fully circular opening. The experimental results showed that the stress–strain curves of specimens containing cavities exhibited multiple stress reductions prior to peak strength, which led to a sudden increase in the accumulated AE count-rate. As the b:a ratio was increased, the uniaxial compressive strength, crack initiation stress and peak strain of cavity specimens all decreased linearly. Tensile fractures, shear fractures, and compound shear-tensile fractures were all observed to emanate from the cavities. Compared to the intact specimen, the failure mode of cavity specimens comprised a mixture of tensile and shear cracks, emanating from the tips (or surfaces) of the oval cavity. For specimen with a cavity angle of 45°, when the b:a ratio was below 1/2, no tensile crack from the surface of short axis was initiated, whereas tensile crack was observed clearly after b:a = 1/2. This study not only increases our understanding of mechanical failure behavior in fractured rock, but also enhances our knowledge of underground tunneling or roadway stability.