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1
Content available Failure characteristics of W strap in coal mine support
Feng Xiaowei, Xue Fei, Feng Xiaotian, Zhao Tongyang
Archives of Mining Sciences
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2022
|
Vol. 67, no. 2
289--302
EN
W strap is a crucial surface support component for underground coal mine roadways. In this study, the failure characteristics of the W strap in the field are discussed, and the loading characteristics of the strap and the faceplate are numerically and experimentally analysed. Afterwards, a loading apparatus capable of reappearing the loading environment of the strap in the field is fabricated. This loading device, combined support systems consisting of a bolt, faceplate and strap is tested under different simulated strata conditions. Failure patterns of the strap are evaluated by the 3D scanning method, and proper selection of a faceplate is explored. Results indicate that a domed faceplate can achieve a favourable supporting effect on strata, and thus it is favoured compared with a square domed faceplate. In addition, rock cavity and rock integrity beneath the strap are essential factors determining the servicing life of the overall supporting system.
2
Content available A methodology to estimate permeability in porous and fissured rock specimens at laboratory scale
Estevez-Ventosa Xian, Gonzalez-Molano Nubia Aurora, Blazquez-Pascual Vanesa, Alverellos Jose, Alejano Leandro R.
Archives of Mining Sciences
|
2020
|
Vol. 65, no. 4
821--833
EN
The correct management of underground works, petroleum and gas reservoirs and geothermal appli-cations relies on the hydromechanical behaviour of rock masses. We describe a laboratory approach to measuring permeability for different types of rock specimens. A laboratory system was designed and set up using rock mechanics equipment (a servo-controlled hydraulic press, a Hoek cell, a pump for injecting water and a scale for measuring the volume of water flow). To verify the validity of the permeability measurements, tests were carried out on a reference porous rock (Corvio sandstone), with results showing good agreement with those published in the literature. Tests were subsequently carried out on artificially fissured granite specimens with different joint patterns, submitted to various confinement stresses up to 20 MPa. Results showed good agreement with traditional Klinkenberg test results. Other tests done with artificially fissured specimens are described for demonstrative purposes.
3
Content available Research of the collapsibility of the European loess – review
Lal Agnieszka
Budownictwo i Architektura
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2019
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Vol. 18, nr 1
4--10
EN
Foundation of the buildings on the loessial soil is often associated only with difficulties resulting from the possibility of the collapse of the ground. For these reason, loess is too often unfairly disqualified as the construction subsoil in spite of its good strength and strain parameters. Thanks to continuous development of research and publications of the results, reliable data regarding loess are spread and, as a consequence, loess becomes more and more common soil used in the geotechnical engineering. Loess collapsibility has been studied since the middle of the 20th century, nevertheless, only the computer techniques and specialist laboratory and microstructural tests, that have been developed from the end of last century, helped us to find an answer to the important questions regarding the occurrence of this phenomenon. Detailed mechanisms that cause sudden loess volumetric reduction due to humidity and load, and the elements that affects the collapsibility are still studied. Furthermore, varied technics are researched, including in-situ tests, which allow estimating the risk of collapse, as well as the methods of its elimination. The aim of this paper is to systematize the directions of current studies of European loess collapsibility and to indicate their most significant results. The review was made on the basis of the scientific publications published in the Polish and international journals as well as the Journal Citation Reports (JCR) Web of Science database.
4
Content available remote Stress concentration factors of shear connection by composite dowels with MCL shape
Kożuch Maciej, Lorenc Wojciech
Archives of Civil and Mechanical Engineering
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2019
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Vol. 19, no. 1
32--46
EN
In this paper, the authors present studies leading to the evaluation of the elastic resistance of the steel part of a continuous shear connection named MCL dowel. The MCL dowel is now the most commonly used shape of continuous connector, chosen among many others for its combination of good fatigue, elastic, and ultimate resistances. A method for the calculation of stress in the steel dowel is described in the paper. It is based on mathematical derivations followed by FE analysis. It is assumed that the steel connector is stressed as a result of a global stress state at the dowel root (being a part of the entire beam) and of a local effects of longitudinal shearing between the steel and concrete parts. Results of the mathematical derivations are confirmed experimentally. Full-scale tests of beam elements were performed with measures of strain in many points of selected connectors. A comparison of strains derived from the proposed design methodology and measured during the experimental tests is shown and discussed. The results herein presented are fundamental research which were one of backgrounds for fatigue limit states of composite dowels for purposes of implementation of composite dowels to the second version of Eurocode 1994-2.
5
Content available remote Characterization of the uniaxial compression behaviour of unreinforced masonry - sensitivity analysis based on a numerical and experimental approach
Sousa R., Guedes J., Sousa H.
Archives of Civil and Mechanical Engineering
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2015
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Vol. 15, no. 2
532--547
EN
Experimental testing of masonry is a difficult, expensive and time consuming process, involving the use of large facilities and a significant number of samples to achieve representative results. On the contrary, computer simulations are practical tools that avoid most of the previous disadvantages. However, such tools are based on experimental evidences and demand experimental results to be validated. These aspects motivated the development of strategies based on numerical models and experimental tests. However, numerical sensitivity analyses based on this approach to predict the behaviour of masonry are not easily found or developed. The main objective of this work is to perform a sensitivity analysis by using computer simulations of laboratory tests to predict the compressive behaviour of unreinforced concrete masonry made from materials with different mechanical properties and geometrical layouts. A three dimensional micro-modelling with continuous finite elements and an elastic–plastic damage constitutive model were used to simulate the masonry behaviour. This numerical model was previously calibrated and validated through experimental data obtained from a small number of laboratory tests. The results obtained showed accuracy and a good agreement with the known aspects of the compressive behaviour of masonry, demonstrating the ability to perform numerical sensitivity analyses with few laboratory resources.
6
Content available Ocena możliwości oznaczenia granicy plastyczności metodą penetrometru stożkowego
Jaśkiewicz K., Wszędyrówny-Nast M.
Przegląd Geologiczny
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2014
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Vol. 62, nr 10/2
588--593
EN
The plastic limit of soils was first described by Atterberg in 1911. The thread-rolling test became one of the standard tests of soil mechanics. In recent years this method has been the subject of much criticism. This paper reviews the original method of plastic limit determination as proposed by Atterberg and the fall cone methods for determining at the same time both the liquid and the plastic limits of soils. The tests were performed on 748 samples representing a wide range of soil type with different clay content ranging from 4 to 79%.
7
Content available remote Ochrona rurociągów przed wytrącaniem się parafiny z ropy naftowej
Bęben D.
Nafta-Gaz
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2014
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R. 70, nr 10
684--689
PL
W artykule opisano zjawiska wytrącania się asfaltenów i parafiny oraz badania, jakie należy wykonać w celu ich ograniczenia. Szczególną uwagę zwrócono na skład rop naftowych, określenie temperatury wytrącania się parafiny, temperatury krzepnięcia ropy naftowej oraz na dobranie środków chemicznych w celu ograniczenia tych zjawisk. Opracowano program badań laboratoryjnych, którym należy poddać wytypowane najlepsze środki chemiczne wspomagające wydobycie, aby zastosować je w kopalniach.
EN
The article describes the phenomenon of the precipitation of asphaltenes and paraffins and research to be done to limit them. Particular attention was paid to the composition of crude oils, determination of wax precipitation temperature, solidification of petroleum and chemical selection in order to limit these phenomena. A program of laboratory tests, to select the best chemicals to use to supporting production and to be applied in mines was developed.
8
Content available remote Badanie katalitycznej skuteczności metaloorganicznych modyfikatorów spalania w testach laboratoryjnych
Wojtasik M., Żak G., Stępień Z.
Przemysł Chemiczny
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2012
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T. 91, nr 12
2452-2455
PL
Opisano wyniki badań katalitycznej skuteczności modyfikatorów spalania w procesie utleniania sadzy. Badano cztery modyfikatory spalania typu FBC (fuel born catalyst). Trzy z nich to dodatki zsyntezowane w Instytucie Nafty i Gazu, a jeden to komercyjny dodatek FBC stosowany do wspomagania procesów regeneracji filtrów cząstek stałych DPF (diesel particulate filter) w silnikach produkowanych w koncernie Volkswagen. Skuteczność katalityczną dodatków FBC określono za pomocą testów laboratoryjnych polegających na wyznaczaniu temperatury utleniania sadzy w obecności badanych katalizatorów.
EN
Three organometallic combustion modifiers were prepd. and compared with a com. Fe one in respect to their catalytic activity in combustion of soot. The Fe-Co modifier was more efficient than the com. one.
9
Content available Method of evaluation of degradation of bio-mechanical tooth-composite filling system
Niewczas A., Pieniak D., Niewczas A. M.
Diagnostyka
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2010
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nr 2(54)
51-58
EN
This paper describes a method of an enhanced life evaluation of dental fillings based on the observation of the enlargement of the marginal fissure between the filling and hard tissue of the tooth. A width of marginal fissure was considered as the functional parameter of the whole tooth-filling system in the conducted tests. In this study development of the fissure influenced by the cyclic changes of thermal loads was analyzed. The extracted human teeth were used in the tests. In which a model lesions with microhybrid composite fillings were applied. All tests were conducted on the dedicated test stand. After performance of fatigue tests, measurements of the width of marginal fissure were taken by means of SEM electron scanning microscope and optical microscope with computer image analyzer. On this basis a risk of functional unfitness of the tooth-filling system was estimated.
PL
W artykule opisano metodę przyspieszonej oceny trwałości wypełnień stomatologicznych na podstawie obserwacji rozbudowy szczeliny brzeżnej pomiędzy wypełnieniem a twardą tkanką zęba. W warunkach prowadzonych badań jako miarę zdatności czynnościowej całego systemu ząb - wypełnienie przyjęto szerokość szczeliny brzeżnej. Autorzy przeprowadzili analizę rozwoju szczeliny pod wpływem cyklicznie zmiennych obciążeń cieplnych. Do badań wykorzystano usunięte zęby ludzkie. W zębach wypreparowano modelowe ubytki i założono wypełnienia z kompozytu mikrohybrydowego. Badania zostały przeprowadzone na specjalnie opracowanym stanowisku badawczym. Po wykonaniu testów zmęczeniowych przeprowadzano pomiary szerokości badanej szczeliny brzeżnej, wykorzystując elektronowy mikroskop skaningowy SEM. Na tej podstawie oszacowano ryzyko niezdatności użytkowej układu ząb - wypełnienie.
10
Content available Engineering geology investigations for foundation design in extension of 'Strachocina' natural gas underground storage in flysch Carpathians
Bednarczyk Z.
Gospodarka Surowcami Mineralnymi
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2009
|
T. 25, z. 3
289-301
EN
In the paper results of soil investigations for design of underground gas storage infrastructure foundations are presented. By the year 2012 Polish Oil and Gas Company will increase storage capacity of 150 mln m3, over two times. It will be necessary to make foundation of compressors, gas cold storages and buildings on slopes built from fysch deposits. They are characterized by different strength parameters and complicated tectonically. Investigations included core drillings, undisturbed sampling, ground penetration radar (GPR) scanning, geotechnical laboratory index, consolidation, oedometer IL and direct shear-box tests. Different test methods, including ground movements inclinometer and piezometer measurements together with slope stability analysis allowed soils characterization. Significant differences between flat area localized on top with shallow depth of stiff rocks and colluviums valleys to the north and south were detected. Investigations proved that foundation of infrastructure will be possible, but it requires changing in design project including some buildings and other elements of infrastructure. For some parts of slopes piles foundations have to be constructed. Also control monitoring measurements will be necessary.
PL
W artykule przedstawiono wyniki badań podłoża gruntowego dla celów posadowienia obiektów infrastruktury związanych z podziemnym magazynowaniem gazu. Do roku 2012 planuje się zwiększyć pojemność magazynów Strachocina ponad dwukrotnie, o 150 mln m3. Niezbędne jest w tym celu posadowienie sprężarek, chłodni gazu i innych budynków na stoku antykliny fliszowej, cechującej się zmiennymi parametrami wytrzymałościowymi i skomplikowaną budową tektoniczną. W celu rozpoznania budowy podłoża wykonano wiercenia rdzeniowe, opróbowanie NNS, profilowania GPR, badania podstawowych parametrów fizycznych gruntów, edometryczne badania ściśliwości oraz badania parametrów wytrzymałościowych gruntów w aparacie bezpośredniego ścinania. Zastosowanie różnorodnych metod badawczych, monitoringu inklinometrycznego i piezometrycznego oraz modelowanie stateczności pozwoliło na charakterystykę podłoża gruntowego. Stwierdzono wyraźną różnicę pomiędzy płaskim obszarem zlokalizowanym na szczycie antykliny, charakteryzującym się płytkim zaleganiem skał zwięzłych a dolinami na północ i południe od niego, gdzie wykryto przemieszczenia wgłębne. Posadowienie projektowanej infrastruktury, w taki sposób, aby zapewnić jej maksymalne bezpieczeństwo, jest możliwe. Wymagać to będzie jednak zmian w projekcie, przeniesienia części obiektów oraz posadowienia pozostałych na fundamentach palowych. Niezbędne będzie także prowadzenie monitoringu w celu kontroli wykonanych zabezpieczeń.
11
Content available remote Cechy wytrzymałościowe elementu gabionowej ściany oporowej w świetle badań modelowych
Surowiecki A., Kozłowski W.
Archiwum Instytutu Inżynierii Lądowej
|
2007
|
Nr 3
309-314
PL
Praca dotyczy gambionowych ścian oporowych jako sposobu zabezpieczenia budowli ziemnych dróg samochodowych i kolejowych przed osuwiskami skarp. Przedstawiono próbę oceny charakterystyk wytrzymałościowych gambionu w oparciu o przeprowadzone badania odkształceń modeli fizycznych gambionu. W szczególności oszacowano: współczynnik nacisku poziomego, wytrzymałość na ścinanie, wpływ zastosowania koszy siatkowych i poziomego zbrojenia na zwiększenie nośności.
12
Content available remote Abrasive wear resistance of hardfacing materials
Brożek M., Suchanek J.
International Journal of Applied Mechanics and Engineering
|
2004
|
Vol. 9, no spec.
27-31
EN
The phenomena connected with friction and wear processes are the most frequent cause of engineering components damage. The damage of even only one component results many times in the necessity of the whole engine plant shutdown (in the worse cause in its breakdown), what evokes the owner's minor or larger losses. That is the reason, why in last years the task of the service life prolongation (wear decrease) comes to foreground. There are several possibilities to solve this problem. The use of surfacing technology - making of special wear resistant overlay on the functional part surface - is one of them. But the manufacturers and sellers do not give the wear resistance information of their overlay materials. In the practice the optimum selection of surfacing could be based on the own experiments or on the published tests results. This paper contains the laboratory wear resistance test results of selected hardfacing materials. The tests were realized at the modified pin abrasion testing machine with abrasive cloth. From the test evaluation it follows that the overlays wear resistance is a complex material property and it is not possible to evaluate it only on the basis of partial information about their chemical composition, metallographic structure or mechanical properties. On the basis of the test results it is possible to stay, that at present the adequate number of first-rate overlay materials are on the market.
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