Fast, non-destructive measurement of roof-bolt loads

Skrzypkowski, Krzysztof; Korzeniowski, W.; Zagórski, Krzysztof; Dominik, Ireneusz; Lalik, Krzysztof

doi:10.2478/sgem-2019-0013

Cited by 20 publications

(16 citation statements)

References 14 publications

(18 reference statements)

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“…In case of stratification appearing above the bolted zone, the rock bolt support loses its functionality and most often the roof rocks collapse. For this reason, monitoring of the rock mass and the bolt support is necessary [38][39][40]. Some uncertainties are also related to the strain of the bolt rod, embedded on the resin cartridges along the entire length, where the unbound section is very short, usually the thread part of the bolt rod.…”

Section: Model Of Rock Bolt Support Under Influence Of Geomechanical Seismic Eventsmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Model Of Rock Bolt Support Under Influence Of Geomechanical Seismic Eventsmentioning

confidence: 99%

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

et al. 2020

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“…The beam model described in equation ( 14) does not determine the influence of the compressive force P 0 in a complex SAS system model. The relation in equation ( 13) can be substituted into equation (9), where in a case of free vibrations of the beam without actuator: f(x,t) ¼ 0, the equation describing the dispersion properties of transverse waves can be obtained.…”

Section: Beam Modelmentioning

confidence: 99%

Modeling of self-excited stress measurement system

Dominik

Lalik

Flaga

2020

Journal of Low Frequency Noise, Vibration and Active Control

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In the paper two types of numerical models of the self-excited acoustical system are presented. This new type of auto-oscillating system is used for stress change measurement in constructions and rock masses. The essence of the self-excited acoustical system is to use a vibration emitter and vibration receiver placed at a distance, which are coupled with a proper power amplifier, and which are operating in a closed loop with a positive feedback. This causes the excitation of the system. The change of the velocity of wave propagation, which is associated with the change of the resonance frequency in the system is caused by the deformation of the examined material. Stress changes manifest themselves in small but detectable variations of frequency. The first of the presented models was created on the basis of estimating the model parameters by identification of the sensor–conditioner–amplifier–emitter system. The second mathematical model was delivered from the force–charge equation of the piezoelectric transducers: the sensor and the emitter. The model of the loaded beam, which determined the response of any beam point to the force applied to any other beam point is also presented.

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“…In addition, the station was equipped with one line encoder, recording the total elongation to break. During the entire duration of the static tensile process, all data from individual sensors was recorded using a specialized Catman-Easy measuring technique program [18][19][20]. To Figures 12b, 13b and 14b have been attached Figures 12a, 13a and 14a, showing the standard deviations for five tests.…”

Section: Load-displacement Characteristics For Rock Bolt Support Instmentioning

confidence: 99%

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

Skrzypkowski

2019

Energies

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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.

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Fast, non-destructive measurement of roof-bolt loads

Cited by 20 publications

References 14 publications

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

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

Modeling of self-excited stress measurement system

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

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