Assessment of roof fall risk in longwall coal mines

Prusek, S.; Rajwa, S.; Wrana, Aleksander; Krzemień, Alicja

doi:10.1080/17480930.2016.1200897

Cited by 59 publications

(50 citation statements)

References 11 publications

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“…One of the most important properties of roof rocks determining their ability to transform into caving is the tensile strength. This strength is the natural ability of the rock mass to resist stratification and caving of the roof rocks into the space (void) left after the mined coal as a result of vertical forces [39,40].…”

Section: The Porosity and Permeability Of Goaves With Cavingmentioning

confidence: 99%

The Impact of the Strength of Roof Rocks on the Extent of the Zone with a High Risk of Spontaneous Coal Combustion for Fully Powered Longwalls Ventilated with the Y-Type System—A Case Study

Tutak

Brodny

2019

Applied Sciences

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During the ventilation of longwalls in hard coal mines, part of the air stream migrates to the goaves with caving. These goaves constitute a space (void) filled with rocks following coal extraction. In the case where these goaves contain coal susceptible to spontaneous combustion, the flow of such an air stream through the goaves may lead to the formation of favourable conditions for coal oxidation, self-heating and spontaneous combustion. Such an area is referred to as the zone with a particularly high risk of spontaneous coal combustion (endogenous fires). The location and extent of this zone depend on many factors, with one of the most important being the permeability of the goaves which determines the tensile strength of the roof rocks forming the caving. This strength determines the propensity of these rocks to transform into the state of caving and the degree of tightness of the cave-in rubble (treated as a porous medium). The purpose of the present paper is to determine how the tensile strength of roof rocks influences the extent of the zone with a particularly high risk of spontaneous coal combustion (endogenous fires) in caving goaves of the longwalls ventilated with the Y-type system. To achieve this goal, model-based tests were conducted for a region of the longwall mined with caving and ventilated with the Y-type system. Critical air speed and oxygen concentration values in the caving goaves of this longwall were determined for the actual conditions of exploitation. These parameters define the risk zone of spontaneous coal combustion. The tests also helped to determine the extent of this zone, depending on the strength of the rocks forming the caving. The results obtained unequivocally indicate that the type of rocks forming the caving affects its permeability and the extent of the risk zone for spontaneous coal combustion. At the same time, the distribution of this zone is substantially different than in the case of other ventilation systems. The results obtained are of real practical significance for preventive measures to reduce fire risks. The effectiveness of these measures significantly improves the safety of mining exploitation.

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Section: The Porosity and Permeability Of Goaves With Cavingmentioning

confidence: 99%

The Impact of the Strength of Roof Rocks on the Extent of the Zone with a High Risk of Spontaneous Coal Combustion for Fully Powered Longwalls Ventilated with the Y-Type System—A Case Study

Tutak

Brodny

2019

Applied Sciences

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“…Static loads are the result of slow movements and deformations of the rock mass. Dynamic loads are the result of rapid changes in the state of balance in the rock mass [7,8].…”

Section: Introductionmentioning

confidence: 99%

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

Szurgacz

2018

E3S Web Conf.

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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.

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“…The research concerning the selection of the roof support which parameters would be suitable for given mining and geological conditions does not include the control system based on electrohydraulics [5][6][7]. At the same time it is necessary to pay particular attention to the reliability in terms of power supply, so that the individual elements of the longwall complex function properly [8,9].…”

Section: Introductionmentioning

confidence: 99%

Analysis characteristics determination of electrohydraulic control system operation to reduce the operation time of a powered roof support

Szurgacz¹

2018

E3S Web Conf.

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Abstract. The article discusses basic functions of a powered roof support in a longwall unit. The support function is to provide safety by protecting mine workings against uncontrolled falling of rocks. The subject of the research includes the measures to shorten the time of roof support shifting. The roof support is adapted to transfer, in hazard conditions of rock mass tremors, dynamic loads caused by mining exploitation. The article presents preliminary research results on the time reduction of the unit advance to increase the extraction process and thus reduce operating costs. Conducted stand tests showed the ability to increase the flow for 3/2-way valve cartridges. The level of fluid flowing through the cartridges is adequate to control individual actuators.

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Assessment of roof fall risk in longwall coal mines

Cited by 59 publications

References 11 publications

The Impact of the Strength of Roof Rocks on the Extent of the Zone with a High Risk of Spontaneous Coal Combustion for Fully Powered Longwalls Ventilated with the Y-Type System—A Case Study

The Impact of the Strength of Roof Rocks on the Extent of the Zone with a High Risk of Spontaneous Coal Combustion for Fully Powered Longwalls Ventilated with the Y-Type System—A Case Study

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

Analysis characteristics determination of electrohydraulic control system operation to reduce the operation time of a powered roof support

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