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    Wyświetlanie 1-5 z 5
    Tytuł:
    The analysis of selected methods of the yielding of a circular arch support made of V profiles
    Autorzy:
    Rotkegel, Marek
    Szot, Łukasz
    Fabich, Sławomir
    Powiązania:
    https://bibliotekanauki.pl/articles/1853839.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    wał
    podpora stalowa
    metoda elementów skończonych
    shaft
    circular support
    arch support
    Opis:
    Steel yielding arch support constructed of V profiles is commonly used to protect galleries and, in some cases, to reinforce or secure a shaft support. For this purpose, a closed, circular-shaped arch support is used, with arches overlapped by clamps that are typical for this type of construction. The support has high resistance to the impact of even (distributed over the entire surface of the support) load, however, as a result of significant deformation associated with a change in the radius of the curvatures, the support shows limited yielding capacity. This is due to the increase in resistance to slide on the locks, resulting from changes in the geometry of the ring caused by the rock mass. This article presents the results of research and analysis concerning the elements of the arch support with notches in arches. The research team tested the effect of the depth and location of the notches of the section’s flanges on the load impacting on the clamp’s bolts and the strength of the roof support. Moreover, the tests covered the influence of the number and location of clamps in a frictional joint on the change in the nature of work and yielding capacity. Finally, the research included both strength tests of the support’s elements, as well as strength analyses based on the finite element method.
    Źródło:
    Archives of Mining Sciences; 2020, 65, 3; 531-550
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimisation of selected parameters of the shield support base dedicated for the condition of a weak floor
    Autorzy:
    Rajwa, Sylwester
    Bock, Sven
    Powiązania:
    https://bibliotekanauki.pl/articles/2203341.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    modelowanie numeryczne
    eksploatacja węgla
    podpora hydrauliczna
    numerical modelling
    PFC3D
    shield support
    longwall mining
    Opis:
    In longwall coal exploitation, problems with the proper functioning of the powered shield support often occur. In many cases, it results from the insufficient load-bearing capacity of the ground (floor) and the inability to achieve the set or yield pressure of the shield support. The improper functioning of the shield support may also result from its construction and the lack of optimisation to work effectively on a weak mine floor. This paper presents an attempt to optimise the operating conditions of the base of two-legged shield support based on the field observations and results of the PFC3D numerical calculation. In the framework of the numerical calculations, the impact of the width of the base and the location of the hydraulic legs on the working conditions of shield support on a weak floor were analysed.
    Źródło:
    Archives of Mining Sciences; 2022, 67, 3; 509--529
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Interaction principle of rock-bolt structure and rib control in large deformation roadways
    Autorzy:
    Yuan, Xun
    Yang, Shuangsuo
    Powiązania:
    https://bibliotekanauki.pl/articles/1853892.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    budowa dróg
    kopalnia węgla
    podpora betonowa
    rock-bolt structure
    fluctuation balance law
    large deformation roadway
    thick-board support
    Opis:
    Large deformation in roadways is an inevitable problem faced by many coal mines, and bolt installation is widely adopted to keep roadway stability. To provide a theoretical basis for bolt supporting scheme design in order to eliminate hazards associated with roadway failure, the interaction principle between bolts and the bolted strata should be studied thoroughly. This research attempts to investigate the above principle through theoretical analysis through a group of selected statistics from fifteen different coal mines. At the same time, the thick board support method was proposed and applied for controlling the ribs deformation in a particular coal mine. It is concluded that the interaction of the rock-bolt entity is subjected to the fluctuation balance law. When deformation increases, the bolted structure experiences periodic equilibrium variation. Both the supporting force needed to stabilise the surrounding rocks and the supporting capability of bolted strata show a trend of decrease in this process. The interaction principle of surrounding rocks and bolts is in essence the mechanical phenomenon caused by their mutual load transformation, and the load-carrying capacity varies with the bolted structure’s deformation, which is subjected to the following law: elastic roadway>plastic roadway> fractured roadway>broken roadway. The designed bolted thickness of the ribs should be more than 1/5 of roadway height to make full use of the self-stability of surrounding rocks. Finite Difference Method simulation and on-site monitoring data showed that the roof subsidence and ribs convergence of 2201 roadway in Shuguang coal mine was reduced by 83.7% and 88.6% respectively after utilising the proposed support method, indicating that the thick-board method was effective. Results of this research can lay a foundation for support design in large deformation roadways.
    Źródło:
    Archives of Mining Sciences; 2021, 66, 2; 227-248
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of behaviour of the steel arch support in the geological and mining conditions of the Cam Pha coal basin, Vietnam
    Autorzy:
    Nguyen, Phu Minh Vuong
    Rotkegel, Marek
    Van, Hoang Do
    Powiązania:
    https://bibliotekanauki.pl/articles/1853833.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    podpora stalowa
    analiza numeryczna
    górnictwo wietnamskie
    steel arch support
    profiles of steel arch support
    numerical analysis
    Vietnamese coal mining industry
    Opis:
    In recent years, the Vietnamese coal mining industry has observed a dynamic increase in both its production and efficiency. In Vietnam, the most precious type of coal is anthracite, which is found in the Quang Ninh province. Industrial anthracite deposits are estimated to be over 2 billion Mg. At present, coal deposits are extracted mostly by the underground method. Coal production is gradually increasing in the underground mines in the Quang Ninh area and it is expected to constitute about 75% of the country’s total coal production in 2030. This involves an increase in the number and length of underground workings. Cam Pha is the largest coal basin of Vietnam, located in the Quang Ninh province. So far, the yearly length of underground workings driven in underground mines in the Cam Pha basin is roughly 90÷150 km. About 84 % of these underground workings are supported by the steel arch support made of SWP profile. A similar situation can be observed in Russia, Ukraine, China, India and Turkey. In addition, the average length of repaired underground workings in the Cam Pha basin constitutes approximately 30% of the total length driven . The main cause was reported is loss of underground workings stability. This requires significant material and labour costs as well as the cost of replacing damaged elements. Addi-tionally, it disturbs the continuity of the mining operations.This article presents the results of the numerical modelling of the rock mass around underground wor-kings driven in typical geo-mining conditions for underground coal mines in the Cam Pha basin, supported by the steel arch support made of SWP and V profiles. As a result of the conducted analyses, the range of failure zone of the rock mass around underground workings and the distribution of reduced stress in the steel arch support elements were determined. The effort states of the steel arch support made of SWP22 profile and V21 profile were compared. The simulations considered different inclinations angle of coal seam, following the structure of the rock mass in the Cam Pha basin. The analysis was carried out using the based-finite difference method code, FLAC2D. Based on the obtained results, actions for improving the stability of underground workings driven in the underground mines of the Cam Pha basin were proposed.
    Źródło:
    Archives of Mining Sciences; 2020, 65, 3; 551-567
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental studies of static and dynamic steel arch support load capacity and sliding joint temperature parameters during yielding
    Autorzy:
    Pytlik, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/1853806.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    nośność statyczna
    wyrobisko
    podpora stalowa
    yielding steel arch support
    support shackle torque
    static and dynamic load capacity
    support work
    arch acceleration in sliding joints
    joint sparking and heating temperature during yielding
    Opis:
    Difficult geological and mining conditions as well as great stresses in the rock mass result in significant deformations of the rocks that surround the workings and also lead to the occurrence of tremors and rock bursts. Yielding steel arch support has been utilised in the face of hard coal extraction under difficult conditions for many years, both in Poland and abroad. A significant improvement in maintaining gallery working stability is achieved by increasing the yielding support load capacity and work through bolting; however, the use of rock bolts is often limited due to factors such as weak roof rock, significant rock mass fracturing, water accumulation, etc. This is why research and design efforts continue in order to increase yielding steel arch support resistance to both static and dynamic loads. Currently, the most commonly employed type of yielding steel arch support is a support system with frames constructed from overlapping steel arches coupled by shackles. The yield of the steel frame is accomplished by means of sliding joints constructed from sections of various profiles (e.g. V, TH or U-type), which slip after the friction force is exceeded; this force is primarily dependent on the type of shackles and the torque of the shackle screw nuts. This article presents the static bench testing results of ŁP10/V36/4/A, ŁP10/V32/4/A and ŁP10/V29/4/A yielding steel arch support systems formed from S480W and S560W steel with increased mechanical properties. The tests were conducted using 2 and 3 shackles in the joint, which made it possible to compare the load capacities, work values and characteristics of various types of support. The following shackle screw torques were used for the tests: Md = 500 Nm – for shackles utilised in the support constructed from V32 and V36 sections. Md = 400 Nm – for shackles utilised in the support constructed from V29 sections. The shackle screw torques used during the tests were greater compared to the currently utilised standard shackle screw torques within the range of Md = 350-450 Nm. Dynamic testing of the sliding joints constructed from V32 section with 2 and 3 shackles was also performed. The SD32/36W shackles utilised during the tests were produced in the reinforced versions and manufactured using S480W steel. Since comparative testing of a rock bolt-reinforced steel arch support system revealed that the bolts would undergo failure at the point of the support yield, a decision was made to investigate the character of the dynamics of this phenomenon. Consequently, this article also presents unique measurement results for top section acceleration values registered in the joints during the conduction of support tests at fullscale.Filming the yield in the joint using high-speed video and thermal cameras made it possible to register the dynamic characteristics of the joint heating process at the arch contact point as well as the mechanical sparks that accompanied it. Considering that these phenomena have thus far been poorly understood, recognising their significance is of great importance from the perspective of occupational safety under the conditions of an explosive atmosphere, especially in the light of the requirements of the new standard EN ISO 80079-36:2016, harmonised with the ATEX directive.
    Źródło:
    Archives of Mining Sciences; 2020, 65, 3; 469-491
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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