scholarly journals Impact of geometry of the powered roof support section on the rock mass

2018 ◽  
Vol 71 ◽  
pp. 00001 ◽  
Author(s):  
Dawid Szurgacz
Keyword(s):  
Rock Mass ◽  
Underground Excavation ◽  
Support Section ◽  
Correct Operation ◽  
Mechanical Elements ◽  
Roof Support

The required functions of the powered roof support, the functions it must fulfil and the mechanical elements cause that the support practically continuously works with the rock mass. This applies to the canopy, the floor base and the shield support. Due to the different susceptibility and strength of the rocks, the roof support may lose its stability. This condition results in an uneven section load and difficulties with moving forward the support in the underground excavation. This, in turn, can lead to disturbances in the operation of the entire longwall system. In order to avoid this situation, it is necessary to conduct geometry tests, e.g. section tests for a dedicated testing station using innovative measuring inclinometers. They indicate the importance of proper geometry for proper and correct operation of the support section. The research was carried out with the use of a new methodology designed to test the geometry of powered roof supports. The solutions were developed by the author of the article.

scholarly journals Analysis of rock mass dynamic impact influence on the operation of a powered roof support control system

2018 ◽  
Vol 29 ◽  
pp. 00006 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jaroław Brodny
Keyword(s):  
Rock Mass ◽  
Real Life ◽  
High Energy ◽  
Hard Coal ◽  
Underground Excavation ◽  
Dynamic Impact ◽  
Support Unit ◽  
Geological Conditions ◽  
Innovative Solutions ◽  
Roof Support

A powered roof support is a machine responsible for protection of an underground excavation against deformation generated by rock mass. In the case of dynamic impact of rock mass, the proper level of protection is hard to achieve. Therefore, the units of the roof support and its components are subject to detailed tests aimed at acquiring greater reliability, efficiency and efficacy. In the course of such test, however, it is not always possible to foresee values of load that may occur in actual conditions. The article presents a case of a dynamic load impacting the powered roof support during a high-energy tremor in an underground hard coal mine. The authors discuss the method for selecting powered roof support units proper for specific forecasted load conditions. The method takes into account the construction of the support and mining and geological conditions of an excavation. Moreover, the paper includes tests carried out on hydraulic legs and yield valves which were responsible for additional yielding of the support. Real loads impacting the support unit during tremors are analysed. The results indicated that the real registered values of the load were significantly greater than the forecasted values. The analysis results of roof support operation during dynamic impact generated by the rock mass (real life conditions) prompted the authors to develop a set of recommendations for manufacturers and users of powered roof supports. These include, inter alia, the need for innovative solutions for testing hydraulic section systems.

Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km

2020 ◽  
pp. 67-75
Author(s):  
Van Min Nguyen ◽  
V. A. Eremenko ◽  
M. A. Sukhorukova ◽  
S. S. Shermatova
Keyword(s):  
Rock Mass ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rock Fracture ◽  
Strain Analysis ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Secondary Stress ◽  
Principal Stresses ◽  
Mining Depth

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress-strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of e ≥ 350me and is used to determine rough distances from the roof ( H roof) and sidewalls ( H side) of an underground excavation to the 3 boundary e = 350me (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths.

scholarly journals Geometrical Tests of Powered Roof Support Positioning in a Longwall Complex

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Dawid SZURGACZ ◽  
Sergey ZHIRONKIN ◽  
Konrad TRZOP ◽  
Stefan VÖTH ◽  
Leszek SOBIK ◽  
...  
Keyword(s):  
Rock Mass ◽  
Research Team ◽  
Surrounding Rock ◽  
Support Structure ◽  
Roof Support

A powered roof support protects people and equipment in the longwall from potential dangerposed by the surrounding rock mass. The study to determine the position of the powered roof supportwas conducted in an active longwall. The research team made measurements of the geometric height ofthe powered roof support structure located in the longwall complex. The main objective of this studywas to determine the position of the powered roof support in actual underground conditions. Theanalysis of the results provided data on whether the assumed height of the longwall was maintainedduring operation of the complex.

A method to estimate the pressure arch formation above underground excavation in rock mass

2018 ◽  
Vol 71 ◽  
pp. 382-390 ◽  
Author(s):  
X.X. Kong ◽  
Q.S. Liu ◽  
Q.B. Zhang ◽  
Y.X. Wu ◽  
J. Zhao
Keyword(s):  
Rock Mass ◽  
Underground Excavation

scholarly journals Analysis of load of a powered roof support’s hydraulic leg

2018 ◽  
Vol 71 ◽  
pp. 00002 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny
Keyword(s):  
Rock Mass ◽  
Hydraulic System ◽  
Impact Load ◽  
Load Condition ◽  
Dynamic Impact ◽  
Registration System ◽  
Free Falling ◽  
The Impact ◽  
Impact Mass ◽  
Roof Support

The main purpose of the powered roof support is to protect headings from the impact of the rock mass. The result of such impact is static and dynamic load impacting the support section, which is carried by its construction. The basic elements of the construction of the support are hydraulic legs, whose task is to ensure adequate strength of its setting. Particularly in the case of dynamic impact of the rock mass, these legs are exposed to a very unfavourable load condition. Therefore, it is necessary to conduct tests to determine the parameters of operation for this type of loads. The paper presents the results of tests on the hydraulic leg subjected to impact load with free falling impact mass. The purpose of the research was to determine the parameters of the leg's operation, i.e. the time periods of pressure in the space under the piston and other elements of the hydraulic system. The tests were conducted in compliance with designed methodology and included innovative registration system. The obtained results clearly indicate the correctness of the adopted assumptions. According to the authors, the results should be applied during selection and operation of a powered roof support.

scholarly journals Case Analysis of Damages to Control Hydraulics of the Leg in the Powered Roof Support Section

2019 ◽  
Vol 105 ◽  
pp. 03013
Author(s):  
Janina Świątek ◽  
Kazimierz Stoiński
Keyword(s):  
Coal Mining ◽  
Case Analysis ◽  
Hard Coal ◽  
Support Section ◽  
Full Extension ◽  
Safety Measures ◽  
Bench Tests ◽  
Hard Coal Mining ◽  
Roof Support

The article discusses a case of security hazard in a longwall equipped with a properly selected chock shield support with two legs, technically efficient, introduced to the market and for operation in compliance with the requirements covering Polish hard coal mining. As a cause of the hazard an accidental coincidence was indicated, such as the occurrence of a tremor at an area with unfavourable geometry for the operation of the support section and leg (including the shift of the double-telescopic leg from the 1st to the 2nd hydraulic stage) at the time of the mining process. Immediate safety measures were applied successfully. They were aimed at minimizing the conditions dangerous to the crew. The section was withdrawn and spragged again. As a result, the leg operated in full extension mode of the 1st hydraulic stage, obtaining the required strength and geometry of the section and leg. The presented case study will be additionally supplemented in the future with selected analytical and bench tests.

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