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Abstract

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.

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Authors and Affiliations

Marek Rotkegel
ORCID: ORCID
Łukasz Szot
Sławomir Fabich
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Abstract

The article is the result of a project aimed at developing and implementing a design of composite accessories for support in excavations located in underground hard coal mines. The research team verified the possibility of using elements made of prefabricated composite structural profile as an alternative to steel and reinforced concrete lining elements used to improve support’s stability and protect against rockfall.
This paper includes a research experiment on the possibilities of using a composite C-profile element as lining made in the pultrusion technology with a longitudinal position of the roving. The prefabricated structural profiles were adapted to the function by designing seatings for fitting the flanges for arch support’s V-profiles. Prototypes of these elements were subjected to bench tests in compliance with the guidelines for testing mesh linings. In addition, computer simulations using the finite element method were carried out.
The values obtained during the tests were compared with the requirements for lightweight mesh and included the Polish standard PN-G-15050 and reinforced A-type concrete lining defined in the standard ­PN-G-06021. The team determined the areas where material strength exceeded and the structure was damaged. Despite the limited quantity of laboratory tests and lack of field tests in actual mining conditions, it was possible to address the argument of the research and determine whether it is possible to use C-profile made in the pultrusion technology as a lining element.
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Bibliography

[1] PN-G-15050:2018-01 Obudowa wyrobisk górniczych. Siatki okładzinowe zgrzewane.
[2] PN-G-06021:1997 Obudowa górniczych wyrobisk korytarzowych. Okładziny żelbetowe.
[3] M. Rotkegel. Wpływ sposobu montażu siatek okładzinowych na ich pracę. Przegląd Górniczy 70 (3), 79-85 (2014).
[4] J. Olszewski, Leksykon górniczy: praca zbiorowa. Katowice: Wydawnictwo Śląsk (1989).
[5] L . Nickels, The future of pultrusion. Reinf. Plast. 63 (3), 132-135 (2019). DOI: https://doi.org/10.1016/j.repl.2019.01.003
[6] G .G. Litwinskij, G.I. Gajko, N.I. Kyldyrkajew, Stalnyje ramnyje kriepi gornych wyrabotok. Kijew: Technika (1999).
[7] M. Grodzicki, M. Rotkegel, The concept of modification and analysis of the strength of steel roadway supports for coal mines in the Soma Basin in Turkey. Studia Geotechnica et Mechanica 40 (1), 38-45 (2018). DOI: https://doi.org/10.2478/sgem-2018-0006
[8] G .I. Gayko, M. Rotkegel, Issliedowanija niesuszcziej sposobnosti arocznoj kriepi pri razlicznych wariantach nagrużienia. Ugoł Ukrainy 2, 45-47 (2003).
[9] P. Horyl, R. Snuparek, P. Marsalek, K. Pacześniowski, Simulation of laboratory tests of steel arch support. Arch. Min. Sci. 62 (1), 63-176 (2017). DOI: http://doi.org/10.1515/amsc-2017-0012455
[10] H. Filcek, J. Walaszczyk, A. Tajduś, 1994. Metody komputerowe w geomechanice górniczej. Śląskie Wydawnictwo Techniczne (1994).
[11] R .D. Cook, D.S. Malkus, M.E. Plesha, R.J. Witt, Finite Element Modeling for Stress Analysis. John Wiley & Sons, Inc. (2002).
[12] CO SMOS/M User’s Guide, Los Angeles, Structural Research & Analysis Corp. (1999).
[13] E. Rusiński, Metoda elementów skończonych. System COSMOS/M. Wydawnictwo Komunikacji i Łączności (1994).
[14] A. Pytlik. Tests of steel arch and rock bolt support resistance to static and dynamic loading induced by suspended monorail transportation. Studia Geotechnica et Mechanica 41 (2), 81-92 (2019). DOI: https://doi.org/10.2478/sgem-2019-0009
[15] A. Pytlik. Comparative bench testing of steel arch support systems with and without rock bolt reinforcements. Arch. Min. Sci. 64 (4), 747-764 (2019). DOI: http://doi.org/10.24425/ams.2019.131064
[16] PN-G-15022:2018-11 Odrzwia podatne z kształtowników korytkowych – Wymagania wytrzymałościowe i badania.
[17] PN-G-15024:2017-10 Obudowa wyrobisk górniczych – Rozpory stalowe dwustronnego działania.
[18] PN-G-15026:2017-04 Obudowa wyrobisk górniczych – Strzemiona oraz złącza odrzwi z kształtowników korytkowych – Badania wytrzymałościowe.
[19] PN-G-14050:1998 Betonity fundamentowe do obudowy odrzwiami z łuków korytkowych wyrobisk górniczych poziomych i mało nachylonych – Wymagania i badania.
[20] PN-G-15092:1999 Kotwie górnicze – Badania.
[21] PN-G-15533:1997 Górnicza obudowa indywidualna – Stojaki cierne – Wymagania i badania.
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Authors and Affiliations

Marek Rotkegel
1
ORCID: ORCID
Jerzy Korol
1
ORCID: ORCID
Dagmara Sobczak
1
ORCID: ORCID

  1. Central Mining Institute, Plac Gwarków 1, 40-166, Katowice, Poland
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Abstract

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. Additionally, it disturbs the continuity of the mining operations.

This article presents the results of the numerical modelling of the rock mass around underground workings 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.

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Authors and Affiliations

Phu Minh Vuong Nguyen
ORCID: ORCID
Marek Rotkegel
ORCID: ORCID
Hoang Do Van
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Abstract

Main sources of emission of benzene and its alkylated derivatives to the atmospheric air, particularly the vehicular ones, are characterized in the paper. Growing use of fuels. especially unleaded gasoline, leads to emission of considerable amounts of these aromatic hydrocarbons. The paper presents and discusses results of determinations of the content of benzene and its alkylated derivatives in engine fuels. Also emission factors of these hydrocarbons from commonly used in Poland types of cars, both with spark- and self-ignition engines, are considered. Profiles of investigated hydrocarbons in fuels and exhaust gases were determined. Respectively compared profiles proved the motor vehicles responsible for main part of the benzene and its alkylatcd derivatives in air in the vicinity of communication arteries.
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Authors and Affiliations

Magdalena Żak
Jan Konieczyński
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Abstract

The mining of hard coal deposits at increasingly greater depth leads to an increase in hazards related to the loss of stability of steel arch supports as a result of excessive static and dynamic loads. Camber beam reinforcement via rockbolting is often utilised in order to improve the stability of the yielding steel arch support.

This article presents the results of comparative bench tests of the ŁP10/V36-type steel arch support, tested with and without reinforcement by means of self-drilling bolts with drunken R25 threads, using short joists formed from V32 and V25 sections. It also presents the results of comparative tests of the ŁPP10/4/V29/I-type steel arch support, tested with and without reinforcement by means of rock bolts with trapezoidal Tr22/13 threads, using short joists formed from V25 sections. The obtained test results, in the form of load courses and work values of the steel arch and mixed (arches and rock bolts) support systems, demonstrate that the utilisation of mixed support may significantly improve the stability of workings, particularly immediately after they are driven. A mixed support system quickly achieves its maximum load capacity together with a significant increase in its work value. It may thus prevent the stratification of the rocks surrounding the working, and therefore better utilise the self-supporting capacity of the rock mass. As evidenced by the test results, the mixed support work may be as much as 3.5 times as great compared to the steel arch support at the beginning of the height reduction process initiated by loading – i.e. until its reduction by a presupposed value of 100 mm.

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Authors and Affiliations

Andrzej Pytlik
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Abstract

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 full scale.

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.

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Authors and Affiliations

Andrzej Pytlik

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