scholarly journals Tests of steel arch and rock bolt support resistance to static and dynamic loading induced by suspended monorail transportation

2019 ◽  
Vol 41 (2) ◽  
pp. 81-92 ◽  
Author(s):  
Andrzej Pytlik
Keyword(s):  
Dynamic Loading ◽  
Coal Mines ◽  
Rock Bolt ◽  
Hard Coal ◽  
Maximum Speed ◽  
Arch Support ◽  
Roadway Support ◽  
Rock Bolt Support ◽  
Static And Dynamic Loading ◽  
Bolt Support

AbstractAt 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.

scholarly journals Evaluation of Rock Bolt Support for Polish Hard Rock Mines

2018 ◽  
Vol 35 ◽  
pp. 01006 ◽  
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Laboratory Tests ◽  
Underground Mining ◽  
Rock Bolt ◽  
Test Facility ◽  
Hard Coal ◽  
External Diameter ◽  
Copper Ore ◽  
Hard Coal Mining ◽  
Rock Bolt Support ◽  
Bolt Support

The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead “Olkusz – Pomorzany” mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt “Olkusz – 20A” is able to overcome the load.The second purpose of the study was to obtain load – displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.

Analysis of Yielding Steel Arch Support with Rock Bolts in Mine Roadways Stability Aspect

2014 ◽  
Vol 59 (3) ◽  
pp. 641-654 ◽  
Author(s):  
Tadeusz Majcherczyk ◽  
Zbigniew Niedbalski ◽  
Piotr Małkowski ◽  
łukasz Bednarek
Keyword(s):  
Support System ◽  
Support Systems ◽  
Coal Mines ◽  
Rock Bolt ◽  
Rock Bolts ◽  
Mining Conditions ◽  
Arch Support ◽  
The Stability ◽  
Rock Bolt Support ◽  
Rockbolt Support

Abstract The result of the search for new technological solutions in the field of support for roadways in coal mines has in recent years been the widespread use of steel arch with rockbolt support systems. The efficiency of these systems is affected among other things by the option of installing rock bolts after the actual driving the mine roadway, the increased load capacity that these systems can support, and their resistance to dynamic weight. Large variation in the way that these steel arch support can be connected using different types of rock bolts necessitates mining research revealing the effectiveness of such solutions. Although the steel arch with rockbolt support system is used in the majority of European coal mines, it is still not possible to apply templates of schemes due to the diversity of geological and mining conditions. Therefore, throughout a period of several years, the authors of this article conducted research in situ under conditions of different schemes related to connecting arched support frames with rock bolts, with only selected results being presented in the article. The measurements of convergence, load supported by the system frame, load supported by the rock bolts, and the stratification of roof rocks were analyzed, carried out in two roadways with yielding steel arch support in which strand bolts were applied. The article also proposes the index for working maintenance nuw, used in preliminarily assessing the stability of a given working with a limited number of data concerning geomechanical conditions. Additionally considered are empirical methods used in Poland for designing steel arch with rock bolt support systems. The results of mine research indicate that strengthening yielding steel support with strand bolts through steel beams maintains the stability of a roadway, even when exposed to the exploitation stress. Aside from the impact of exploitation, deformations of the support system are negligible, despite the fact that the tensile forces acting on the rock bolts can reach values of up to 160 kN. Under favorable geological and mining conditions, support system frames can be spread up to 1.5 m apart when using rock bolts between them. The conducted measurement of convergence during a three year period revealed a compression amounting to a few centimeters. The results obtained by the research fully confirm the effectiveness of combined yielding steel arch with rock bolt support systems under different mining conditions.

scholarly journals Laboratory testing of a long expansion rock bolt support for energy-absorbing applications

2018 ◽  
Vol 29 ◽  
pp. 00004 ◽  
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Underground Mining ◽  
Rock Bolt ◽  
Underground Mines ◽  
Test Facility ◽  
Hard Coal ◽  
Static Tests ◽  
Additional Support ◽  
Energy Absorbing ◽  
Rock Bolt Support ◽  
Bolt Support

The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.

scholarly journals Case Studies of Rock Bolt Support Loads and Rock Mass Monitoring for the Room and Pillar Method in the Legnica-Głogów Copper District in Poland

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2998 ◽  
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Underground Mining ◽  
Mechanical Load ◽  
Ground Surface ◽  
Rock Bolt ◽  
Copper Ore ◽  
Essential Condition ◽  
Rock Bolting ◽  
Rock Bolt Support ◽  
The Impact ◽  
Bolt Support

The article presents the impact of geological and mining factors on the stability of room excavations in the Legnica-Głogów Copper District (LGOM) in Poland. In underground mining, the primary task of bolting of mining excavations is to ensure their stability as an essential condition of work safety. Appreciating the role and importance of the rock bolting in Polish ore mining; rock bolt load sensors were designed, manufactured and tested under laboratory conditions. The purpose of the research was to characterize the sensors and determine the elastic range of the bearing plate, which are an integral part of the sensor. The sensors have been verified in industrial conditions. The tests were carried out in the underground copper ore mine in Poland. Three rooms in the exploitation field were selected for testing, where exploitation was carried out at a depth of 809–820 m below the ground surface with the application of room and pillar with roof deflection and maintaining the central part of the field. The exploitation field included 60 rooms and pillars. The effectiveness of the mechanical load sensor of the expansion rock bolt support has been experimentally confirmed. Based on mine research, it was found that the largest increases in the load of the rock bolting, vertical stress and convergence occur in the middle of the mining field.

scholarly journals Effect of Near-Wave Field Mining Tremors on the Rock Bolt Support Behaviour within Stress Domain

2019 ◽  
Vol 105 ◽  
pp. 01007
Author(s):  
Witold Pytel ◽  
Krzysztof Fuławka ◽  
Piotr Mertuszka
Keyword(s):  
Wave Field ◽  
Dynamic Effect ◽  
Stability Loss ◽  
Rock Bolt ◽  
Risk Level ◽  
Roof Fall ◽  
Rock Bolt Support ◽  
Stratum Deformation ◽  
The Impact ◽  
Bolt Support

One of the most serious hazard in the underground copper mining in Poland is the roof fall hazard. The scale and intensity of this type of events depends on several factors. Due to seismic activity, weaker roof strata can loosen and deform, generating additional load on the rock bolt support. The type of load depends strictly on the course of stratum deformation as well as on the intensity of the dynamic effect in the form of a seismic wave. Continuous monitoring is then necessary to determine the risk level of stability loss within existing excavations in order to minimize the probability of serious accidents. The following study analyses the impact of tremors recorded within the near-wave field upon the stress change in the instrumented rock bolts.

scholarly journals Adjustment of the Yielding System of Mechanical Rock Bolts for Room and Pillar Mining Method in Stratified Rock Mass

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2082 ◽  
Author(s):  
Krzysztof Skrzypkowski ◽  
Waldemar Korzeniowski ◽  
Krzysztof Zagórski ◽  
Anna Zagórska
Keyword(s):  
Numerical Modeling ◽  
Impact Energy ◽  
Laboratory Tests ◽  
Ore Deposits ◽  
Rock Bolt ◽  
Rock Bolts ◽  
Damage Area ◽  
Rock Bolt Support ◽  
The Impact ◽  
Bolt Support

The article presents a novel yielding mechanism, especially designed for the rock bolt support. Mechanical rock bolts with an expansion head and equipped with one, two, four and six dome bearing plates were tested in the laboratory conditions. Furthermore, in the Phase2D numerical program, five room and pillar widths were modeled. The main aim of numerical modeling was to determine the maximal range of the rock damage area and the total displacements in the expanded room. The models were made for a room and pillar method with a roof sag for copper ore deposits in the Legnica-Głogów Copper District in Poland. Additionally, in the article a load model of the rock bolt support as a result of a geomechanical seismic event is presented. Based on the results of laboratory tests (load–displacement characteristics), the strain energy of the bolt support equipped with the yielding device in the form of dome bearing plates was determined and compared with the impact energy caused by predicted falling rock layers. Based on the laboratory tests, numerical modeling and mathematical dynamic model of rock bolt support, the dependence of the drop height and the corresponding impact energy for the expanded room was determined.

Study on Rock Bolt Support of Roadway of Coal Mine Using Neural Network

2013 ◽  
Vol 448-453 ◽  
pp. 3799-3802
Author(s):  
Feng Shan Han ◽  
Xin Li Wu
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Coal Mine ◽  
Engineering Application ◽  
Rock Bolt ◽  
Learning System ◽  
Artificial Neural ◽  
Complex Relationships ◽  
Rock Bolt Support ◽  
Bolt Support

The artificial neural network has been widely used in various field of science and engineering. The artificial neural network has marvelous ability to gain knowledge. In this paper, according to principle of artificial neural network , Model of artificial neural network of rock bolt support of roadway of coal mine has been constructed,Learning system of BP artificial neural network has been trained,it is shown by engineering application that artificial neural network can handle imperfect or incomplete data and it can capture nonlinear and complex relationships among variables of a system. the artificial neural network is emerging as a powerful tool for modeling with the complex system. Method and parameters of rock bolt support of roadway of coal mine can be predicated accurately using artificial neural network, that is of significance and valuable to those subjects of investigation and design of mining engineering

Improvement of Design and Installation of Injection Rock Bolt Support

2017 ◽  
Vol 53 (3) ◽  
pp. 513-518 ◽  
Author(s):  
R. A. Ignat’ev ◽  
E. R. Ignat’ev
Keyword(s):  
Rock Bolt ◽  
Rock Bolt Support ◽  
Bolt Support

Laboratory Method for Evaluating the Characteristics of Expansion Rock Bolts Subjected to Axial Tension / Laboratoryjna Metoda Badania Charakterystyk Kotew Rozprężnych Poddanych Rozciąganiu Osiowemu

2015 ◽  
Vol 60 (1) ◽  
pp. 209-224 ◽  
Author(s):  
Waldemar Korzeniowski ◽  
Krzysztof Skrzypkowski ◽  
Łukasz Herezy
Keyword(s):  
Rock Mass ◽  
Laboratory Method ◽  
Operating Conditions ◽  
Rock Bolt ◽  
Test Facility ◽  
Geometrical Parameters ◽  
Rock Bolts ◽  
Axial Tension ◽  
Rock Bolt Support ◽  
Bolt Support

Abstract Rock bolts have long been used in Poland, above all in the ore mining. Worldwide experience (Australia, Chile, Canada, South Africa, Sweden, and USA) provides evidence of rock bolt supports being used for loads under both static and dynamic conditions. There are new construction designs dedicated to the more extreme operating conditions, particularly in mining but also in tunneling. Appreciating the role and significance of the rock bolt support and its use in Polish conditions amounting to millions of units per year, this article describes a new laboratory test facility which enables rock bolt testing under static load conditions. Measuring equipment used as well as the possibilities of the test facility were characterized. Tests were conducted on expansion rock bolt supports installed inside a block simulating rock mass with compression strength of 80 MPa, which was loaded statically as determined by taking account of the load in order to maintain the desired axial tension, which was statically burdened in accordance with determined program load taking into consideration the maintenance of set axial tension strength at specified time intervals until capacity was exceeded. As an experiment the stress-strain characteristics of the rock bolt support were removed showing detailed dependence between its geometrical parameters as well as actual rock bolt deformation and its percentage share in total displacement and deformation resulting from the deformation of the bolt support elements (washer, thread). Two characteristic exchange parts with varying intensity of deformation /displacement per unit were highlighted with an increase in axial force static rock bolt supports installed in the rock mass.

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