Temat: bolt - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Comparative Shear Tests of Bolt Rods Under Static and Dynamic Loading
Autorzy:: Pytlik, Andrzej
Powiązania:: https://bibliotekanauki.pl/articles/178659.pdf
Data publikacji:: 2020
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: rock bolt
laboratory bolt test
static single shear test
dynamic single shear test
shear work
Opis:: This article presents the methodology and results of single shear tests of bolt rods under dynamic impact loading generated by means of a drop hammer. Comparative analysis was also performed for bolt rod load capacity, stress and shear work under static and dynamic (impact) loading. The developed method of single shear testing of bolt rods under impact loading makes it possible to obtain repeatable test results concerning maximum bolt rod shearing force, shear stress and shear work values. Comparative shear tests of four types of bolt rods under static and impact loading showed that the APB-type bolt rods made of AP770 steel, which was characterised by having the highest strength, exhibited the greatest shear work. AM22- type bolt rods exhibited a very similar work value. Though the AM22-type bolt rods made of A500sh steel demonstrated lower strength than the APB-type bolts, as well as a smaller diameter and cross section, they dissipated the impact energy better thanks to their higher plasticity. This could indicate the direction of optimisation for bolt rods in order to increase their impact strength. Mathematical relationships were also formulated for selected tests, describing the real single shear courses F d =f(t ) of bolts under impact loading. The obtained relationships could be applied in the load assessment process of bolt rods intended for use under roof caving, tremor and rock burst conditions.
Źródło:: Studia Geotechnica et Mechanica; 2020, 42, 2; 151-167
0137-6365
2083-831X
Pojawia się w:: Studia Geotechnica et Mechanica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Fast, non-destructive measurement of roof-bolt loads
Autorzy:: Skrzypkowski, Krzysztof
Korzeniowski, Waldemar
Zagórski, Krzysztof
Dominik, Ireneusz
Lalik, Krzysztof
Powiązania:: https://bibliotekanauki.pl/articles/178690.pdf
Data publikacji:: 2019
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: expansion-shell bolt
monitoring
non-destructive method
laboratory tests
Opis:: This paper discusses the pull-out laboratory tests and the monitoring of expansion-shell bolts with a length of 1.82 m. The bolts comprised the KE-3W expansion shell, a rod with a diameter of 0.0183 m and a profiled, circular plate with a diameter of 0.14 m, and a gauge of 0.006 m. The bolts were installed in a concrete block with a compressive strength of 75 MPa. The tests were conducted on a state-of-the-art test stand owned by the Department of Underground Mining of the AGH University of Science and Technology. The test stand can be used to test roof bolts on a geometric scale of 1:1 under static and rapidly varying loads. Also, the stand is suitable for testing rods measuring 5.5 m in length. The stand has a special feature of providing the ongoing monitoring of bolt load, displacement and deformation. The primary aim of the study was to compare the results recorded by two different measurement systems with the innovative Self-Excited Acoustic System (SAS) for measuring stress variations in roof bolts. In order to use the SAS, a special handle equipped with an accelerometer and exciter mounted to the nut or the upset end of the rod was designed at the Faculties of Mining and Geoengineering and Mechanical Engineering and Robotics of the AGH University of Science and Technology. The SAS can be used for non-destructive evaluation of performance of bolts around mining workings and in tunnels. Through laboratory calibration tests, roof bolt loads can be assessed using the in-situ non-destructive method.
Źródło:: Studia Geotechnica et Mechanica; 2019, 41, 2; 93-101
0137-6365
2083-831X
Pojawia się w:: Studia Geotechnica et Mechanica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Reinforcement of underground excavation with expansion shell rock bolt equipped with deformable component
Autorzy:: Korzeniowski, W.
Skrzypkowski, K.
Zagórski, K.
Powiązania:: https://bibliotekanauki.pl/articles/178960.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: rock bolting
expansion shell rock bolt stiffness
deformable component
mining
Opis:: The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread) and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod). There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.
Źródło:: Studia Geotechnica et Mechanica; 2017, 39, 1; 39-52
0137-6365
2083-831X
Pojawia się w:: Studia Geotechnica et Mechanica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Application of long expansion rock bolt support in the underground mines of Legnica-Głogów Copper District
Autorzy:: Skrzypkowski, K.
Korzeniowski, W.
Zagórski, K.
Dudek, P.
Powiązania:: https://bibliotekanauki.pl/articles/178284.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: rebuilding of excavations
long expansion rock bolt support
ore mining
3D printing
Opis:: In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department “Polkowice-Sieroszowice” in the years 2010-2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the “Precymit” material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress–strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in excavations, and it is increasingly frequently used to reinforce roofs and in rebuilding the underground mines of KGHM Polish Copper S.A. In order to conduct the laboratory tests that are most suitable for the mine conditions, and yet are carried out on a laboratory test facility, the Authors used a steel cylinder with an external diameter of 102 mm and a length of 600 mm, which was filled with a core of rock (dolomite) from the roofs of the mine workings. In addition the maximum load that took over the bolt support made of rods and connected with sleeves was determined. For the initial tension, the elastic and plastic range of the maximal displacements, which were measured by the rope encoder, were determined. The statical tests of the expansion rock bolt support were carried out at the laboratory of the Department of Underground Mining in simulated mine conditions. The test facility enables the study of the long bolt rods on a geometric scale of 1:1 for the different ways of fixing. The aim of the laboratory research was to obtain the stress-strain characteristics, of the long expansion rock bolt support with a steel bearing plate and a plate printed on a 3D printer.
Źródło:: Studia Geotechnica et Mechanica; 2017, 39, 3; 47-57
0137-6365
2083-831X
Pojawia się w:: Studia Geotechnica et Mechanica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Tests of steel arch and rock bolt support resistance to static and dynamic loading induced by suspended monorail transportation
Autorzy:: Pytlik, Andrzej
Powiązania:: https://bibliotekanauki.pl/articles/178684.pdf
Data publikacji:: 2019
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: mine transport
suspended monorail
transport-induced static support loading
transport-induced dynamic support loading
steel arch support resistance
rock bolt support resistance
Opis:: At present, the suspended monorail systems constitute a very common means of transportation in the Polish hard coal mines. The main advantages of the suspended monorail include the independence of the route from the working floor surface irregularities and the possibility to transport cargo of significant mass and size. The masses and dimensions of machines and devices transported via monorail have increased considerably in recent times. This particularly concerns the transport of longwall system elements. In Poland, the maximum speed of suspended monorail travel is 2 m/s. Due to the fact that preparations are currently underway to increase the maximum speed above 2 m/s, it is necessary to inspect what influence it will have on work safety and mining support stability. Current operational experience and tests have shown that dynamic loads induced by the suspended monorail transportation have a significant influence on the roadway support stability, working protection durability and on the monorail operators. This is particularly true during the emergency braking of a suspended monorail by means of a braking trolley, where the overloads reach 3g. Bench tests of the selected steel arch and rock bolt support elements utilised in the Polish hard coal mines were conducted in order to determine the resistance of steel arch and rock bolt supports to static and dynamic loads. The article presents the results of the tests conducted on a steel arch support in the form of the sliding joints of an ŁP/V29 yielding roadway support, which is commonly employed in the Polish hard coal mines. Tests of elements of the threaded bolts with trapezoidal threads over the entire rod length were conducted as well. The conducted strength tests of steel arch and rock bolt support elements under static and dynamic loading have shown that dynamic loading has decisive influence on the support’s retaining of its stability. Support element stability decreases along with the increase of the impact velocity. This concerns both the steel arch support and the rock bolt support.
Źródło:: Studia Geotechnica et Mechanica; 2019, 41, 2; 81-92
0137-6365
2083-831X
Pojawia się w:: Studia Geotechnica et Mechanica
Dostawca treści:: Biblioteka Nauki

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