scholarly journals Modified Rock Bolt Support for Mining Method with Controlled Roof Bending

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1868 ◽  
Author(s):  
Krzysztof Skrzypkowski ◽  
Waldemar Korzeniowski ◽  
Krzysztof Zagórski ◽  
Anna Zagórska
Keyword(s):  
Laboratory Tests ◽  
Deformation Energy ◽  
Rock Bolt ◽  
Raw Material ◽  
Mining Method ◽  
Underground Excavations ◽  
Bearing Plate ◽  
Additional Work ◽  
Rock Bolt Support ◽  
Bolt Support

The article presents methods of making the rock bolt support more yieldable, especially for a stratified roof. Alongside the increasing depth of exploitation of raw material deposits, rock bolt support units are more often designed taking into account more intensive deformations and displacements of underground excavations. In the article, a room and pillar method with mined roof bending and roof reinforcement with bolt patterns of 1 m × 1 m, 1.5 m × 1.5 m and 2 m × 2 m is presented. Moreover, the laboratory tests included 1.8 m long bolts, which were embedded segmentally on the lengths of 100 mm, 150 mm and 200 mm were tested. Based on the load–displacement characteristics, the deformation energy for flat and profiled dome bearing plates was calculated. Making the segmentally embedded resin rock bolt support yieldable enabled it to perform additional work. Furthermore, it was found that rock bolt support with a dome bearing plate took over 2.5 times more energy compared to a rock bolt support equipped with a flat bearing plate.

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.

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.

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.

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.

scholarly journals The Influence of Room and Pillar Method Geometry on the Deposit Utilization Rate and Rock Bolt Load

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4770 ◽  
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Three Dimensional ◽  
Rock Bolt ◽  
Utilization Rate ◽  
Variable Geometry ◽  
Rock Destruction ◽  
Destruction Zone ◽  
Increased Strength ◽  
Rock Bolt Support ◽  
Bolt Spacing ◽  
Bolt Support

In this article, a model of ore deposit in form of a lense carried out in the MineScape program, is presented. The lense had a thickness of 30 m, length along the strike 200 m, and the depth buried was for 80 m to 110 m below the surface. In the first layer, counting from the lowest level, a room and pillar method with variable geometry was designed. The width and length dimensions for rooms and pillars were: 4 m, 5 m and 6 m, respectively. For the selected part of the deposit, three variants of the system with variable geometry of rooms and pillars were designed, for which the deposit utilization coefficient was determined. The next stage of the research was to determine the influence of the geometry of the pillars and rooms on the range of the rock destruction zone around room excavations. For this purpose, numerical calculations using the three-dimensional Examine 3D program, based on the boundary element method, were made. The results of numerical tests were used to calculate the load of the rock bolt support, which is currently used in the zinc and lead underground mine “Olkusz-Pomorzany” in Poland. Currently in the mine, the bolt spacing is 1 m × 1 m, and the technology for fixing the bolt rod is based on resin cartridges that completely fill the bolt hole. In order to spread the spacing of the rock bolt support and to apply segmental fixing of the bolt rod, in the laboratory tests, rock bolt supports with increased strength were tested. Based on the results obtained, it was found that the rock bolt can be installed segmentally, using a cement grout, and its spacing can be increased to 2 m.

scholarly journals A new design of support for burst-prone rock mass in underground ore mining

2018 ◽  
Vol 71 ◽  
pp. 00006 ◽  
Author(s):  
Krzysztof Skrzypkowski
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Tensile Tests ◽  
Rock Bolt ◽  
Dynamic Loads ◽  
Rock Bolting ◽  
Rock Bolt Support ◽  
Yielding Support ◽  
Bolt Support

The article presents the basic methods of strengthening room and roadway excavations in underground ore mining. In particular, it was pointed out that the mining support is very often exposed to additional dynamic loads resulting from the mining of the deposit by means of explosives (slight) as well as from the load arising from rock mass tremors. In the article a new design of arch yielding support adapted to dynamic loads, which can be used in long-term access excavations was proposed. For this case, an exemplary spring deflection, which is located in the support foot cylinder, based on the principle of work and energy was calculated. In the case of exploitation room excavations, laboratory tensile tests of the long expansion rock bolt support, which were carried out in the rock bolting laboratory at the Department of Underground Mining AGH were presented. Load-displacement characteristics for long expansion rock bolt support with a particular indication of the elastic and plastic range were presented. In the summary, it was concluded that with the increase in the depth of exploitation, safe and efficient mining will be possible only due to the use of a support with appropriate yielding.

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