Wyniki wyszukiwania - BazTech

1

Development of waste-free technology for processing of all types of limestone waste using solar energy

Zhaiylkhan Nuradin, Sugirov Jiyenbeck, Yerzhanov Kalyy, Shaikhiyeva Kulanda, Nurbayeva Farida

Polityka Energetyczna

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2025

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T. 28, z. 1

33--54

EN

In light of growing environmental concerns and the gradual depletion of conventional energy sources, the development of an efficient technology to process all types of limestone waste using solar energy becomes a crucial step towards a sustainable and environmentally friendly industry. The purpose of this study was to create an innovative technology that can efficiently process various limestone wastes with minimal environmental impact and utilize solar energy as the primary energy source. The study used data on geographical coordinates, solar radiation, hours of sunlight, radiation, climate, and lighting conditions of the Republic of Kazakhstan to assess the potential of solar energy and its impact on the radiation balance and climatic conditions of the country. The creation of innovative technology for processing limestone waste to produce a new building material will reduce the cost of stone extraction, minimize waste accumulation, and improve the environmental situation. This is achieved by optimizing the processing using solar energy, which contributes to the environmental sustainability of production and reduces the consumption of fuel and energy resources in concrete production. The study involved both theoretical and practical experiments to optimise the technological processes of limestone waste processing using solar energy. Furthermore, the environmental conditions of the quarries and solar energy resources were analyzed for the application of solar technology.

PL

W świetle rosnących obaw o środowisko i stopniowego wyczerpywania się konwencjonalnych źródeł energii, opracowanie wydajnej technologii przetwarzania wszystkich rodzajów odpadów wapiennych przy użyciu energii słonecznej staje się kluczowym krokiem w kierunku zrównoważonego i przyjaznego dla środowiska przemysłu. Celem tego artykułu było stworzenie innowacyjnej technologii, która może sku tecznie przetwarzać różne odpady wapienne przy minimalnym wpływie na środowisko i wykorzystywać energię słoneczną jako główne źródło energii. W badaniu wykorzystano dane dotyczące współrzędnych geograficznych, promieniowania słonecznego, godzin nasłonecznienia, promieniowania, klimatu i warun ków oświetleniowych Republiki Kazachstanu w celu oceny potencjału energii słonecznej i jej wpływu na bilans promieniowania i warunki klimatyczne kraju. Stworzenie innowacyjnej technologii przetwarzania odpadów wapiennych w celu produkcji nowego materiału budowlanego obniży koszty wydobycia kamie nia, zminimalizuje gromadzenie się odpadów i poprawi sytuację środowiskową. Osiąga się to poprzez optymalizację przetwarzania przy użyciu energii słonecznej, co przyczynia się do zrównoważenia śro dowiskowego produkcji i zmniejszenia zużycie paliwa i zasobów energetycznych w produkcji betonu. Badanie obejmowało zarówno teoretyczne, jak i praktyczne eksperymenty mające na celu optymalizację procesów technologicznych przetwarzania odpadów wapiennych z wykorzystaniem energii słonecznej. Ponadto przeanalizowano warunki środowiskowe kamieniołomów i zasoby energii słonecznej pod kątem zastosowania technologii słonecznej.

2

Experimental study on triaxial compression mechanical properties of grouting reinforcement of broken surrounding rock

Yang Peng, Pang Dongdong

Archives of Mining Sciences

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2025

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Vol. 70, no. 2

273--291

EN

Grouting is a widely used method of reinforcement for stabilising fractured surrounding rock. To investigate the triaxial compression behaviour of surrounding rock after grouting reinforcement, laboratory-prepared grouted specimens were subjected to triaxial compression tests using an RMT-150B testing system. The analysis focused on the effects of confining stress, particle size, and water-to-cement ratio on the stress-strain behaviour. The internal friction angle and cohesion were determined based on the Mohr-Coulomb criterion. The variations in strain at peak stress and the elastic modulus were clarified, and the failure modes of the grouted specimens were examined. Additionally, Kendall’s correlation analysis was employed to evaluate the relationship between confining stress and other parameters. The results indicate that increasing confining stress significantly enhances the load-bearing capacity of the surrounding rock. The optimal rock particle gradation was observed when the particle size ranged between 5-10 mm, yielding the highest compressive capacity. Conversely, increasing the water-to-cement ratio reduced the strength of the specimens. Among the analysed factors, confining stress exhibited the strongest correlation with peak stress.

3

Development of bit design for breaking rocks with different mechanical properties

Seniushkovych Mykola, Vytvytskyi Ivan, Martsynkiv Oleh, Tyrlych Volodymyr V., Vytiaz Andrii

Nafta-Gaz

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2024

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R. 80, nr 10

615–-624

EN

This paper presents a description of a bit design with a combined cutter layout, aimed at increasing the efficiency of breaking rocks with different mechanical properties. The results from industrial testing of the manufactured bits are analyzed, revealing the need to improve their hydraulic flushing system. Computer modeling was conducted using the Flow Simulation CAD/CAM package of the Solid Works system, where various models of the design options for the bit, the borehole bottom, and a segment of the drill string were created. For each variant, numerical calculations of the fluid motion were carried out using the finite element method. Based on the simulation results, optimal angles of inclination for the jet nozzles relative to the bit axis and their distance from this axis were determined. Key factors influencing the stability of the bit cutters, which destroy the rock by cutting with axial vibrations, were identified, and analytical dependencies for their predictive stability were derived. The wear rate of the bit cutters was determined by instantaneous values of such physical parameters as: the degree of wear, rock cutting speed, temperature, axial loading force on the cutter, and the friction coefficient at the contact between the cutter and rock. Temperature is especially impactful, reaching levels exceeding 1000°C in the cutting zone; it is often regarded as the primary factor influencing bit cutter stability. To maximize the efficiency of rockbreaking in the process of drilling wells, it is necessary to set the following vibration parameters: frequency, amplitude, and vibration mode, which can be determined from the results of mathematical modeling.

PL

W artykule przedstawiono opis konstrukcji świdra wiertniczego z kombinowanym układem ostrzy, mającym na celu zwiększenie efektywności rozkruszania skał o różnych właściwościach mechanicznych. Przeanalizowano wyniki testów przemysłowych wyprodukowanych świdrów, które wykazały potrzebę ulepszenia ich systemu płukania hydraulicznego. Modelowanie komputerowe przeprowadzono przy użyciu pakietu Flow Simulation CAD/CAM systemu Solid Works, w którym utworzono różne modele wariantów projektowych świdra, dna otworu wiertniczego oraz segmentu przewodu wiertniczego. Zidentyfikowano kluczowe czynniki wpływające na trwałość ostrzy, które kruszą skałę poprzez skrawanie drganiami osiowymi oraz wyprowadzono zależności analityczne dla ich przewidywanej stabilności. Stopień zużycia ostrzy określono na podstawie chwilowych wartości takich parametrów fizycznych jak: stopień zużycia, prędkość skrawania skały, temperatura, siła obciążenia osiowego ostrza oraz współczynnik tarcia na styku ostrza ze skałą. Temperatura jest czynnikiem mającym szczególny wpływ, ponieważ osiąga poziomy przekraczające 1000°C w strefie skrawania; jest ona często uważana za główny czynnik decydujący o trwałości ostrza. W celu zmaksymalizowania wydajności rozkruszania skał w procesie wiercenia otworów, konieczne jest określenie następujących parametrów drgań: częstotliwości, amplitudy i trybu drgań, które można określić na podstawie wyników modelowania matematycznego.

4

Kotwy iniekcyjne w gruntach i skałach

Roguska Emilia

Materiały Budowlane

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2024

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nr 2

61--65

5

The meaning of average compressive and tensile strength for Hoek-Brown mi constant determination

Małkowski Piotr, Niedbalski Zbigniew

Archives of Mining Sciences

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2024

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Vol. 69, no. 3

485--508

EN

One of the most widely used failure criteria for rocks in the world is the Hoek-Brown failure criterion. For its use, the mi empirical parameter for a specific rock type is needed. The triaxial compression test is recommended for its determination; however, the full stress path for every rock comprises confined tension as well. This affects the course of the Hoek-Brown envelope, which is non-linear and starts at uniaxial tension. Fifty-one series of tests were carried out for three rock types: sandstone, claystone and limestone, to show the difference between the results of the mi determination, using two different approaches – so-called linear and non-linear. Moreover, the consistency between the developed simplified methods of constant determination and mi were checked. These comprised the UCS-based method, R-index method, TS-based method and advanced regression functions of compressive and tensile strength. The relationship between mi constant and the internal friction angle was checked as well. The analysis of the results showed that the consistency with the regression models developed by researchers depends on the chosen estimator. If it is derived from the triaxial test only, the results are closer to a linear determination of mi constant and have a good correlation with internal friction angle. If both tensile and compressive strength are used for its determination, the non-linear value correlates better with the advanced regression functions, but quite poor with the average compressive strength (R-index method) and tensile strength (TS-based method). Taking into account that every rock retained next to the geotechnical or mining object is not only compressed but also tensed, the non-linear mi interpretation seems to be more correct. The interlayers and discontinuities inside sedimentary rocks increase the scatter of lab results and reduce the accuracy of mi determination.

6

Impact loading of tendon reinforcement systems used for ground control: a critical literature review

Mottahedi Adel, Aziz Naj, Remennikov Alex, Mirzaghorbanali Ali, Marston Kevin

Archives of Mining Sciences

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2024

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Vol. 69, no. 4

711--743

EN

The present paper reports on various test methods and techniques which have been developed throughout the last decades. These methods have been used to evaluate both axial and shear performance of tendons under impact loading mode. Based on the literature review conducted on the scientific documents, published between 1992 and 2024, the developed facilities mainly work based on the direct impact and momentum transfer methods. In the direct impact method, which can be done in-situ and in the laboratory, the impact energy is applied by a mass freely falls to the test sample. In the momentum transfer method, the test assembly, consisting of both the mass and test sample free-fall at the beginning of the test until the movement of the assembly is halted by a stopper, and the momentum of the mass is transferred to the test sample. Besides, most of the current facilities are working based on the direct impact method. It was also found that less research have been conducted on dynamic shear testing, especially high-strength cable bolts, as most of the facilities have been designed for pull testing. In addition, it was found that in dynamic pull-out tests of rock bolts, two main mechanisms of energy absorption are identified: steel plastic deformation and bolt sliding within the encapsulation medium. The first impact plays a key role in energy absorption, causing significant permanent displacements, while the energy consumed in displacing the bolt is more indicative of dynamic behavior than the total input energy. According to the results, the tendons that undergo static deformations before dynamic loading are more prone to failure as some parts of their performance have already lost. Meanwhile, differences between dynamic and static shear tests suggest that dynamic tests require less energy for failure, as friction is ineffective in impact loading. Finally, the study highlights gaps in the current understanding of tendon performance under impact loading, with potential research directions aimed at improving safety in underground excavation.

7

Extracting static elastic moduli of rock through elastic wave velocities

Zhang Yuliang, Gu Yiming, Zhou Hongtu, Yang Lining

Acta Geophysica

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2024

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Vol. 72, no. 2

915--931

EN

In many geological conditions, obtaining the static elastic moduli of crustal rocks is an essential subject for accurate mechanical analyses of crust. The elastic wave method may be the best choice if rock specimens cannot be taken since elastic wave propagation can be applied to in-situ environments. Although many signs of progress have been made in the elastic wave method, some issues still restrict the accurate extraction of static moduli and its applications. A review of this method and its further research prospect is urgently needed. With this purpose, this paper summarized and analyzed the published experimental data about the relationship between the static and dynamic Young’s moduli of rock, and the frequency dependence of wave velocities and dynamic elastic moduli. P- and S-wave velocities, Young’s, and bulk moduli of rock, especially the saturated rock, have strong frequency dependence in a wide frequency range of 10-6-106 Hz. Different rocks or conditions (such as water content, amplitude, and pressure), have different frequency-dependent characteristics. The current elastic wave method can be classified into two methods: the empirical correlation method and the multifrequency ultrasonic method. The basic principle, advantages, and disadvantages of both methods are analyzed. Especially, the reasonability of the multifrequency ultrasonic method was elaborated given the nonlinear elasticity, strain level/rate, and pores/cracks in rock materials. Existing problems and prospects on the two methods are also pointed out, such as the choice of a proper empirical correlation, accurate determination of the critical P- and S-wave velocities, the prediction of Young’s modulus at each strain level, and the reasonability of the method under various water contents and fracture structures.

8

Reductıon of thermal tensıons and temperatures formed ın the trıbonodes and surfaces of the equıpment and tools used ın well workover and restoratıon works

Mustafayev Amir G., Nasirov Chingiz R.

Nafta-Gaz

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2023

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R. 79, nr 10

661--669

EN

The maintenance of equipment and tools used in the workover of oil and gas wells depends on keeping them in good working condition, maintaining the reliability, strength, and temperature endurance of the tool. To restore wells after an accident and bring them back into operation, it is necessary to speed up the drilling and repair work by choosing the right repair equipment and following the existing rules and regulatory documents. The cutting elements of tools working under high pressure and loads are deformed, a tense situation is created in the cutting – a destruction zone and high temperatures (1000–1200°C) occur because of corrosion in the triboknots. The stress-deformation state in the cutting-destruction zone causes the formation of microcracks in the working area of the tool. Microcracks grow after a certain period. Cutting elements are quickly worn, in some cases break and fail quickly. Such cases affect the structural composition of the cutting elements, an increase in temperatures; as a result, riveting occurs. In order to keep the equipment and tools used in the repair in normal working condition, adjusting the mode parameters is one of the important requirements, in addition to taking special care of them. Optimum results obtained in repair and restoration depend on the efficiency of the cutting-destructive tool, longevity, material selection, construction manufacturing technologies, tools that meet modern requirements, dimensions, weight, and internal condition of the well being restored. It is necessary to keep the heat generated in the moving parts of the tool at the required level for the safe performance of restoration work. The thermal regime of cutting and rock-destroying tools depends on the physical-mechanical properties of the objects subjected to destruction, and the effect of thermomechanical stresses generated on the contact surfaces of the tool and the amount of heat released from the working surface. Studying the problems related to heat issues will ensure the temperature tolerance of not only the repair equipment, but also the equipment and tools used in other areas of the oil-field industry.

PL

Utrzymanie urządzeń i narzędzi używanych w rekonstrukcjach odwiertów ropy i gazu zależy od zachowania ich w stanie gotowości do pracy, niezawodności, wytrzymałości oraz trwałości temperaturowej narzędzia. Aby przywrócić odpowiedni stan odwiertów po awarii oraz ponownie rozpocząć ich eksploatację trzeba przyspieszyć prace wiertnicze i naprawy poprzez wybranie właściwych urządzeń naprawczych oraz przestrzeganie istniejących przepisów i dokumentów regulacyjnych. Elementy tnące narzędzi pracujących pod wysokim ciśnieniem i obciążeniami ulegają deformacji, wytwarza się sytuacja naprężenia w strefie tnąco-niszczącej i występują wysokie temperatury (1000–1200°C) w wyniku korozji w węzłach tarcia. Stan naprężenie-odkształcenie w strefie tnąco- -niszczącej powoduje tworzenie mikropęknięć w obszarze roboczym narzędzia. Mikropęknięcia propagują po pewnym czasie. Elementy tnące szybko się zużywają, w niektórych przypadkach szybko pękają i ulegają awarii. Takie przypadki wpływają na skład strukturalny elementów tnących, wzrost temperatury i w rezultacie następuje unieruchomienie. Aby utrzymywać urządzenia i narzędzia używane przy naprawie w normalnych warunkach roboczych, jednym z najważniejszych wymogów jest dostosowanie parametrów trybu pracy, oprócz objęcia ich specjalną uwagą. Dobre wyniki uzyskane w robotach naprawczych i renowacyjnych zależą od sprawności narzędzia tnąco-niszczącego, trwałości, doboru materiałów, technologii produkcji konstrukcji, narzędzia spełniającego nowoczesne wymagania, jego wymiarów, wagi oraz stanu wewnętrznego odwiertu podlegającego renowacji. Dla bezpiecznego wykonania prac renowacyjnych konieczne jest utrzymanie ciepła generowanego w częściach ruchomych narzędzia na wymaganym poziomie. Reżim cieplny narzędzi tnących i niszczących skałę zależy od właściwości fizyko-mechanicznych obiektów podlegających niszczeniu i efektu naprężeń termomechanicznych generowanych na powierzchniach kontaktowych narzędzia oraz od ilości ciepła uwolnionej z powierzchni roboczej. Badanie problemów związanych z zagadnieniami ciepła pozwoli na zapewnienie tolerancji temperaturowej nie tylko urządzenia naprawczego, ale również urządzeń i narzędzi używanych w innych dziedzinach przemysłu złóż ropy.

9

Rock transport after an outburst and the fluidisation phenomenon – can it occur during a dolomite and gas outburst?

Kozieł Katarzyna, Skoczylas Norbert

Archives of Mining Sciences

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2023

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Vol. 68, no. 4

621--638

EN

Rock and gas outburst is a phenomenon in which fragmented rock material is transported deep into a pit. The transport of rock material by gas is a two-phase process. The article deals with the fluidisation of rock material. Considerations on the fluidisation phenomenon were carried out, and experiments were performed to help clarify whether the fluidisation of dolomite is possible. In the last chapter, a discussion was carried out, and the results obtained were analysed regarding the possibility of occurrence in mine conditions.

10

Landslide survey at Cam Mountain (An Giang, Vietnam) by seismic refraction and GPR methods

Nguyen Giang Van, Nguyen Dung Quang, Le Thanh Ngoc

Archives of Mining Sciences

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2023

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Vol. 68, no. 4

603--620

EN

Cam Mountain in An Giang Province, Vietnam, is a granite peak that is severely fractured and eroded on its slopes and summit. Trees cover the top of the mountain and around the side of the mountain. The roads are the primary means of transportation for indigenous people and tourists daily. Recently, there has been a phenomenon of large-sized boulders rolling down from the top of the mountain, causing an accident and killing tourists. To investigate the internal causes of landslides on a 2.3 km road stretch, geophysical profiles using GPR and seismic refraction methods were conducted to clarify the current status of geological structures beneath the road surface. The refractive seismic data analysis revealed four distinct layers based on elastic wave propagation velocity. Velocity values range from 1000 to 3000 m/s for the 2 upper layers corresponding to the weathered, broken, and highly fractured rock layers and in the lower 2 layers from 3000 to more than 4500 m/s, respectively corresponding to less fractured rock on the depth of more than 50 m. According to GPR data, the structural cross-section to an average depth of 30 m is a more complex picture. Detected 6 layers with different degrees of fracture cracking and showing different structural zones. In a few places are the drainage creeks from the mountain. These places need to be monitored regularly to have a basis for predicting landslides and rockfalls in the area of Cam Mountain. Landslides occur in geological rocks which are of different ages: claystone, mudstone, siltstone, shale, or marlstone. The rock-falls occur in more compact rocks: metamorphic or igneous rocks.

11

On the resistance of concrete hollow thin-walled high piers to rock collisions

Huang Yao

Archives of Civil Engineering

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2023

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Vol. 69, nr 3

187--197

EN

Concrete hollow thin-walled high piers (CHTWHPs) located in mountainous areas may be destroyed by the huge impact force of accidental rocks. The study focuses on analyzing the effects of rock impact on the pier, including its impact force, pier damage, dynamic response, and energy dissipation characteristics. The results show that: (1) Increasing the impact height led to a decrease in the peak impact force. Specifically, 15.5% decrease in the peak collision force is induced when the height of rock collision rises from 10 m to 40 m. (2) The damage mode of the pier’s collision surface is mainly oval damage with symmetrical center, radial damage on the side surface, and corner shear failure on the cross section. (3) The peak displacement of bridge pier increases with the increase of collision height. As the collision height increased from 10 m to 40 m, the bridge pier’s peak displacement also increased, rising by 104.2%. (4) The concrete internal energy gradually decreased with increasing collision height, dropping by 36.9% when the height of rock collision rises from 10 m to 40 m. The reinforcement internal energy showed an increase of 78%. The results of this study may provide reference for the rock collision resistance design of CHTWHPs.

12

An evaluation method of rock pore volume compressibility determination using a computed tomography scanned based finite element model

Moosavi Seyed Amin, Goshtasbi Kamran, Kazemzadeh Ezzatollah

Acta Geophysica

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2023

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Vol. 71, no. 1

147--159

EN

This paper has proposed a new perspective of studying internal structure-based tests, the results of which will improve the present experimental methods and enrich our understanding of rock structure-based modeling without any core preparations, with low cost in a short time. Pore volume compressibility (PVC) is an important feature of rock and is related to mechanical and structural behavior of porous rock sample. An accurate evaluation of pore volume compressibility depends on experimental test which is time-consuming and costly. This paper outlines new method for evaluation of PVC of rock cores using a computed tomography (CT) scan-based finite element method (FEM). The verification studies were performed on a series of porous rock cores which were extracted from deep oil reservoirs in Iran. In order to construct a finite element model, a relationship between spatial elastic properties of samples and CT-scanned data images was derived. The samples were scanned by a conic beam computed tomography (CBCT) machine, and the scanned data were converted into a model to simulate PVC tests. The pore volumetric strains were obtained from a linear elastic analysis for each stress and pore pressure step. To validate the finite element analysis (FEA) results, a series of experimental PVC tests were conducted on the pre-scanned samples and PVC curves were extracted. As a result, the predictions calculated from the CT scan-based numerical models have shown a good correlation with the results obtained from laboratory experiments. The results revealed that it is possible to simulate PVC tests using this numerical proposed evaluation method in such a way that the cost and time of the tests were lowered.

13

Interakcja wodoru ze skałą zbiornikową

Cicha-Szot Renata, Leśniak Grzegorz

Nafta-Gaz

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2022

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R. 78, nr 8

580--588

PL

Istnieje szereg metod magazynowania wodoru, do których zaliczyć można stosowanie zbiorników napowierzchniowych, wiązanie w wodorkach metali, nanorurkach węglowych, sieciach metaloorganicznych, ciekłych organicznych nośnikach wodoru czy adsorbentach. Jednak to podziemne magazynowanie wodoru w strukturach geologicznych (PMW) wydaje się kluczowe dla rozwiązania problemu długoterminowego magazynowania dużych ilości energii oraz zwiększenia stabilności sieci energetycznej i poprawy wydajności systemów energetycznych. Kryteria wyboru struktury do magazynowania wodoru obejmują szereg czynników technicznych, ekonomicznych, ekologicznych i społecznych. Jednym z najmniej rozpoznanych obszarów badawczych dotyczących PMW jest utrata wodoru in situ wywołana reakcjami geochemicznymi, które mogą wpływać na parametry petrofizyczne oraz wytrzymałość skał uszczelniających. W artykule przeanalizowano reakcje, jakie mogą wystąpić podczas magazynowania wodoru w strukturach geologicznych. Na podstawie studium literaturowego wskazano grupy minerałów, które mogą wpływać na zmiany pojemności magazynowej oraz na czystość gazu. Należą do nich w szczególności węglany, anhydryt, ankeryt i piryt, które stanowiąc skład matrycy skalnej lub cementu, mogą znacząco wpływać na potencjał magazynowy analizowanej struktury. Podczas kontaktu z wodorem minerały te ulegają rozpuszczeniu, w wyniku czego uwalniane są m.in. jony Fe2+, Mg2+, Ca2+, SO4 2−, HCO3 − , CO3 2−, HS− . Jony te wchodzą nie tylko w skład minerałów wtórnych, ale również na skutek dalszych reakcji z wodorem zanieczyszczają magazynowany nośnik energii domieszkami CH4, H2S i CO2, co ogranicza możliwości dalszego wykorzystania wodoru. Zwrócono również uwagę na możliwość wystąpienia rozpuszczania kwarcu, którego szybkość zależy od stężenia jonów Na+ w solance złożowej oraz pH. Ponadto pH wpływa na reaktywność wodoru i zależy w dużej mierze od temperatury i ciśnienia, które w trakcie pracy magazynu będzie podlegało częstym cyklicznym zmianom. W artykule omówiono wpływ warunków termobarycznych na analizowany proces, co powinno stanowić podstawę do szczegółowej analizy oddziaływania skała–wodór– solanka dla potencjalnej podziemnej struktury magazynowej.

EN

There are several hydrogen storage methods, including surface tanks, metal hydrides, carbon nanotubes, organometallic networks, liquid organic hydrogen carriers, or adsorbents. However, underground hydrogen storage (UHS) appears to be crucial in solving the problem of long-term storage of large amounts of energy, increasing the power grid's stability and improving energy systems' efficiency. The criteria for selecting a hydrogen storage structure include a number of technical, economic, ecological, and social factors. One of the least recognized research areas concerning UHS is the in situ loss of hydrogen caused by geochemical reactions that may affect sealing rocks' petrophysical parameters and strength. The article presents the reactions that may occur during hydrogen storage in geological structures. Based on a literature study, groups of minerals that may affect changes in storage capacity and gas purity have been indicated. These include, in particular, carbonates, anhydrite, ankerite, and pyrite in both the rock matrix and the cement. Upon contact with hydrogen, these minerals dissolve, releasing, among others, Fe2+, Mg2+, Ca2+, SO4 2– , HCO3 – , CO3 2– , HS– ions. These ions are not only components of secondary minerals but also, as a result of further reactions with hydrogen, pollute the stored energy carrier with admixtures of CH4, H2S and CO2, which limits the possibilities of further hydrogen use. The possibility of quartz dissolution, the rate of which depends on the concentration of Na+ ions in the reservoir brine and the pH, was also noted. Moreover, pH influences the reactivity of hydrogen and depends mainly on temperature and pressure, which will be subject to frequent cyclical changes during the operation of the storage. This review paper discusses the influence of thermobaric conditions on the analyzed process, what should be a base for detailed analysis of the rock-hydrogen-brine interaction for the potential underground storage structure.

14

Badania laboratoryjne przyczepności stwardniałych zaczynów cementowych z dodatkiem nanotlenku glinu do wybranych formacji skalnych

Rzepka Marcin, Kędzierski Miłosz

Nafta-Gaz

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2022

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R. 78, nr 1

22--30

PL

Artykuł przedstawia wyniki badań laboratoryjnych przyczepności zaczynów cementowych do trzech formacji skalnych, tj. rdzeni powstałych z piaskowca, mułowca oraz węgla kamiennego. Przygotowane rdzenie skalne (przed zalaniem zaczynem cementowym) poddawane były procesowi przemywania w różnych cieczach (prowadzono też badania dla tzw. rdzeni suchych). Do badań przyczepności wytypowano recepturę zaczynu cementowego zawierającą 1% nanotlenku glinu (n-Al2O3) oraz recepturę konwencjonalną (porównawczą, tj. bez udziału nanokomponentu). Badane zaczyny cementowe miały dobre parametry technologiczne, umożliwiające ich zastosowanie do uszczelniania kolumn rur okładzinowych w otworach wiertniczych o temperaturze dynamicznej około 35°C oraz ciśnieniu około 15 MPa. Po wykonaniu szeregu badań laboratoryjnych stwierdzono, że zaczyn zawierający dodatek 1% n-Al2O3 w wyraźny sposób podnosił przyczepność kamienia cementowego do formacji skalnej. Uzyskane wartości przyczepności dla zaczynu z n-Al2O3 w porównaniu z wartościami otrzymanymi dla zaczynu konwencjonalnego są około 30–40% wyższe. Analizując przyczepność kamienia cementowego (z dodatkiem i bez dodatku nanokomponentu) do różnego rodzaju formacji skalnych, należy zaznaczyć, że: najwyższą przyczepność zanotowano w przypadku piaskowca, nieco niższą – mułowca (około 80–85% wartości przyczepności uzyskanej dla piaskowca), a najniższą – węgla (około 70–75% wartości przyczepności uzyskanej dla piaskowca). Zależność ta zachodzi w podobny sposób w przypadku rdzeni „suchych”, jak i przemytych płuczką, buforem oraz cieczą przemywającą. Należy podkreślić niezwykle istotną rolę odpowiedniego procesu przemywania otworu wiertniczego przed wykonaniem zabiegu cementowania rur okładzinowych. Zastosowanie samego buforu może okazać się niewystarczające. Dodatkowe użycie odpowiednio dobranej cieczy przemywającej pozwala skutecznie usunąć resztki osadu filtracyjnego pozostającego na powierzchni formacji skalnej po jej przewierceniu, co powinno znacznie poprawić stan zacementowania otworu wiertniczego.

EN

The article presents the results of laboratory tests of adhesion of cement slurries to three rock formations, i.e. sandstone, mudstone and hard coal cores. The prepared rock cores (before being poured over with cement slurry) were washed in various fluids (tests were also conducted for the so-called “dry” cores). The adhesion tests were carried out for two selected cement slurries recipes: cement slurry containing 1% aluminum nanoxide (n-Al2O3) and conventional cement slurry (comparative, i.e. without the addition of nanocomponents). The tested cement slurries had good technological parameters, enabling their use for sealing casing columns in boreholes with a dynamic temperature of approx. 35°C and a pressure of approx. 15 MPa. After a series of laboratory tests, it was found that the slurry containing the addition of 1% n-Al2O3 significantly increased the adhesion of the cement stone to the rock formation. The obtained values of adhesion for the n-Al2O3 slurry, compared to the values obtained for the conventional slurry, are about 30–40% higher. When analyzing the results of adhesion of cement stone (with and without the addition of a nanocomponent) to various types of rock formations, it is stated that the highest values of adhesion was obtained for sandstone, slightly lower for mudstone (about 80–85% of the adhesion value obtained for sandstone) and the lowest for coal (about 70–75% of the adhesion value obtained for sandstone). This dependence is similar in the case of “dry” cores and those washed with mud, spacer fluid and washing fluid. It should be emphasized that the proper process of washing the borehole is very important prior to cementing the casing. The use of a spacer fluid alone may not be sufficient. The additional use of a properly selected washing liquid increases the mud-cake removal efficiency, which should significantly improve the quality of borehole cementing.

15

Significance of a new preliminary treatment method of the Pen206_18 borehole penetrometer’s pressure readouts for a reliable analysis of rock stress-strain parameters

Pierszalik Rafał

Archives of Mining Sciences

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2022

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Vol. 67, no. 1

159--178

EN

This article describes some selected aspects of a preliminary treatment of measurement cycle results obtained by a new Pen206_18 type hydraulic borehole penetrometer (a borehole jack type), a tool of an in situ determining of mechanical properties of rocks. The pre-treatment of the measurement cycle results is a necessary step to prepare the data for a following appropriate analysis of stress-strain parameters of rocks. Aforementioned aspects are focused mainly on a pre-treatment of hydraulic pressure readouts. The Pen206_18 type penetrometer is a modified version of a standard Pen206 type penetrometer. The standard version, based on a digital measurement of a critical hydraulic pressure, has been in use in polish hard coal mines for almost 15 years to determine various rock strength parameters. In contrary, the Pen206_18 type penetrometer now provides simultaneous recording of two main measurement cycle parameters (hydraulic pressure and a head pin stroke) during the whole measurement cycle duration. A recent modification of the penetrometer has given an opportunity to look closer at various factors having an influence on the measurement cycle data readouts and, as a consequence, to lay a foundation for a development a new penetrometric method of determining stress-strain parameters of rocks. In this article it was shown that just before a main stage of the measurement cycle, a transitional stage could occur. It complicates a determination of the beginning of an useful set of measurement cycle data. This problem is widely known also in other static in situ methods of determining stress-strain parameters. Unfortunately, none of various known workouts of this problem were sufficiently adequate to the pre-treatment of the penetrometric measurement cycle results. Hence, a new method of determining the beginning of the useful set of pressure readouts has been developed. The proposed method takes into account an influence of an operational characteristics of the measuring device. This method is an essential part of a new pre-treatment procedure of the Pen206_18 measurement cycle’s pressure readouts.

16

Overlying sand-inrushing mechanism and associated control technology for longwall mining in shallow buried coal seams with the soft surrounding rock

Wang Fangtian, Shao Dongliang, Zhang Cun, Zhang Chenkai, Song Ziyu

Archives of Mining Sciences

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2022

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Vol. 67, no. 4

681--697

EN

Taking the sand-inrushing accident of the Selian No. 1 coal mine in the Ordos of inner Mongolia as the research background, four main factors of sand-inrushing, including sand source, channel, sand-breaking power, and flowing space, were analysed. The disaster formation process (SCPS) illustrated that sand-inrushing disasters in shallowly buried coal seams with soft surrounding rock have the characteristics of being significantly influenced by mining, the development of vertical overburden channels, and sufficient space for water-sand mixed particles to flow. Universal Distinct Element Code (UDEC) software has been used to reveal that the vertical cracks in the overburden between the coal wall and support undergo a process of development and expansion along with the cumulative stress of mining. This showed that the vertical fissure through the overburden is the main pathway for the disaster. Combined with the site conditions, disaster occurrence mechanism, and numerical simulation results, a comprehensive prevention and control technology based on the working face and roadway grouting to block the channel was proposed. It contains reasonable mining height and optimisation of advancing speed, so that safe and efficient mining of coal seams in shallow-buried soft surrounding rocks could be achieved.

17

The role of water content in rate dependence of tensile strength of a fine-grained sandstone

Cai Xin, Cheng Chuanqing, Zhao Yuan, Zhou Zilong, Wang Shaofeng

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e58, 2022

EN

Rocks in nature are commonly in partially saturated conditions and exposed to dynamic loads. In this study, to explore the coupled effects of water content and loading rate, dynamic Brazilian disc experiments were conducted on Yunnan sandstone samples with four levels of water content (from air-dried to water-saturated) under various loading rates (from 100 to 600 GPa/s) using a split Hopkinson pressure bar. The test results show that for each water content, the dynamic tensile strength of sandstone is positively sensitive to loading rate. The rate dependence of tensile strength increases as the rise of water content. The change trends of tensile strength against water content depend on loading rate: as water content rises, the tensile strength displays the manner of “no change followed by fast drop” at loading rates of 10–4 and 100 GPa/s. However, when the loading rate is above 200 GPa/s, the tensile strength increases first and then declines. The turning point occurs at water content between 1.0 and 2.0%. These observations can be interpreted with the competition between water weakening and enhancing effects under different loading conditions.

18

Experimental and numerical study on the indentation behavior of TBM disc cutter on hard-rock precutting kerfs by high-pressure abrasive water jet

Cheng Jian‑Long, Yang Sheng‑Qi, Han Wei-Feng, Zhang Zuo-Ru, Jiang Zi-Hao, Lu Jun-Fu

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e37, 2022

EN

Tunnel boring machine (TBM) excavation of high strength or highly abrasive rock strata has some limitations, such as slow advance speed, low rock-breaking efficiency, and significant increase in the disc cutter changes and construction cost. To improve the rock boreability, a novel breakage method for hard rocks using a TBM disc cutter penetrating into kerfs precut by a high-pressure abrasive water jet is explored. With a confining pressure of 5 MPa, a series of cutter indentation tests and particle flow simulations of granite with two precutting kerfs are carried out to investigate the indentation behavior and the breaking efficiency. The effects of the kerf depth and the kerf spacing on the normal indentation force, rock chip volume, and specific energy are studied. The initiation, propagation, and coalescence modes of the surface and internal cracks and the failure mechanism are analyzed. The results show that the average peak force decreases significantly with the increase of the kerf depth, and the maximum rock chip volume and minimum specific energy are obtained at a kerf depth of 18.14 mm. The failure mode of kerf specimens after two indentations could be divided into the flat and slow shallow failure, one-sided inclined failure, and two-sided inclined failure. The micro-crack distribution of a single shallow kerf under low confining pressure is similar to that of intact rocks, while it is oblate and semi-elliptical under high confining pressure. However, for a single deep kerf, the breakage consists of a wedge-shaped crushed zone, a failure zone, and a damage zone around the kerf boundary and the bilateral inclined cracks, which are almost not affected by the confining pressure.

19

Effect of loading characteristics and specimen size in split Hopkinson pressure bar test on high-rate behavior of phyllite

Mishra Sunita, Khetwal Anuradha, Chakraborty Tanusree, Basu Dipanjan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e212, 2022

EN

Split Hopkinson pressure bar (SHPB) tests are performed on Himalayan phyllite rock with five different specimen sizes and with different gas gun pressures and striker bar lengths of the SHPB device. The high-strain-rate phyllite parameters investigated are the peak stress, strain at peak stress, dynamic increase factor (DIF), strain energy absorbed, and dynamic modulus. It is observed that the dimensions of the phyllite specimens and the SHPB loading characteristics (i.e., the gas gun pressure and striker bar length) have a strong impact on the phyllite response. Given that SHPB specimen dimensions are small compared to any field rock mechanics problem, the rate-dependent rock mass properties are also determined for each rock using Hoek–Brown criteria. Numerical simluations of the SHPB tests are performed using finite element (FE) analysis in conjunction with the strain rate-dependent Johnson–Holmquist (JH-2) constitutive model to calibrate the JH-2 model parameters for phyllite. The calibrated JH-2 model parameters are dependent on the phyllite specimen size and on the magnitudes of the gas gun pressure and striker bar length. The different calibrated parameters corresponding to different specimen sizes and different SHPB loading characteristics are used to perform FE analysis of a tunnel constructed in phyllite rock and subjected to a blast load. The FE results show that the tunnel responses can significantly differ with strain rate-dependent JH-2 model parameters with difference in the mean stress and vertical displacement at the crown of the tunnel in the phyllite rock as high as 126% and 250%, respectively.

20

Natural radionuclides in rocks and their association with the mineralogy of rocks in Dakshina Kannada region of southern India

Lokesh Narsha, Vinutha Pudiyaneravana Ramanand, Malleshi Kavasara, Narayana Yerol

Acta Geophysica

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2022

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Vol. 70, no 5

2149--2160

EN

The radioactivity levels of natural radionuclides 226Ra, 232Th, and 40K in the rocks of Dakshina Kannada region of southern India were measured by NaI (Tl) gamma-ray spectrometer. The specific activities of 226Ra, 232Th, and 40K ranged from 4.2±0.4 to 74.5±1.7 Bq kg−1, 14.5±0.7 to 83.5±1.6 Bq kg−1, and 172±3 to 964±7 Bq kg−1 with the mean of 25.1±1.0 Bq kg−1, 36.1±1.0 Bq kg−1, and 502±5.0 Bq kg−1, respectively. The normality of the frequency distribution curves of 226Ra, 232Th, and 40K was tested using the Kolmogorov–Smirnov test. The radiological hazard indices were computed from the measured activity concentration of natural radionuclides in rocks and these were found to be within acceptable levels. To investigate the sources of radioactivity, the minerals involved in the rocks were detected using XRD and FTIR. The mineralogical studies reveal that the principal sources of gamma radiation in the study area are 232Th-rich phosphates and 40K-bearing feldspars.