Distribution law of floor stress during mining of the upper protective coal seam

Zhang, Yongjiang

doi:10.1177/0036850420930982

Cited by 7 publications

(8 citation statements)

References 45 publications

(47 reference statements)

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“…According to reference [20], the pressure of key block B on small coal pillar can be approximately considered as follows :…”

Section: Main Roof Fracture Structure Form Of Island Working Facementioning

confidence: 99%

Study on overburden rock structure characteristics and surrounding rock control technology of island working face

Xingping,

Haoyu,

Hao

et al. 2024

Preprint

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Aiming at the technical problems of safe and efficient mining under the complex conditions of strong mine pressure and multiple disasters in island working face, taking ZF2822 working face of Xiagou Coal Mine as the background, theoretical analysis, numerical simulation and field measurement are used to explore the fracture structure characteristics and surrounding rock control technology of overlying rock in island working face. The results show that the ten morphological structures of the main roof fracture can be divided into four typical symmetrical structures and six asymmetric structures. According to the stress calculation formula of the key block B to the coal pillar, the stress characteristics of the 10 structures are classified and the risk classification is carried out. Among them, the (a), (e), (f) and (g) structures belong to level I. Four typical structures (a), (b), (c) and (d) were constructed to simulate the stress and strain characteristics of surrounding rock. The overlying strata subsidence displacement values of (a), (b), (c) and (d) at the roadway are 1.75 m, 1.5 m, 0.8 m and 0.6 m respectively, and the maximum stresses are 26.6 MPa, 19.5 MPa, 15.5 MPa and 10.0 MPa respectively, (a) > (b) > (c) > (d). Therefore, the surrounding rock control technology of gob-side roadway in island working face is put forward, the fracture structure of basic roof is determined and the reasonable applicable type of gob-side roadway is selected. The results after pressure relief show that the average daily microseismic energy of ZF2822 working face after pressure relief is 0.87×104J, which is about 42.38 % lower than that of April. The average stress is 1.13 MPa lower than that of the mining before the pressure relief area, and the decrease is 22.42 %. During the mining process of the working face in the pressure relief area, the average stress is 0.49 MPa lower than that before the pressure relief area, and the decrease is 9.02 %. It shows that the pressure relief has played a very good effect and provides a reference for the same type of mine.

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“…According to reference [20], the pressure of key block B on small coal pillar can be approximately considered as follows :…”

Section: Main Roof Fracture Structure Form Of Island Working Facementioning

confidence: 99%

Study on overburden rock structure characteristics and surrounding rock control technology of island working face

Xingping,

Haoyu,

Hao

et al. 2024

Preprint

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“…After the upper protective layer is mined, the roof and floor coal strata in the goaf will periodically appear in three stages, compression, expansion, and recovery, with the advancement of the working face [21]. In order to better study the characteristics of the bottom and roof collapse, the collapse characteristics when the working face is advanced to 30 m, 50 m, 80 m, and 140 m were selected for analysis.…”

Section: Analysis Of Collapse Characteristics Of Working Face Advanci...mentioning

confidence: 99%

Study on Overburden Movement and Fissure Evolution Law of Protective Layer Mining in Shallow Coal Seam

Liu

2022

Energies

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This study aims to effectively solve the problem of the destruction of the coal roof and floor overlying rock after mining the protective layer, and determines whether the gas in the protected layer can be effectively released. We do this based on the engineering background of the Weng’an Coal Mine; research and analysis of the movement of the roof and floor overlying rocks; the evolution of cracks and the pressure relief characteristics of the protected layer after mining the protective layer; and through theoretical analysis and similar simulation experiments. Through numerical simulation, it was found that the protected layer was depressurized due to the mining of the protective layer, and the decompression rate of the protected layer was 0.2–0.8. In addition, the overall expansion rate of the protected layer was greater than the requirements of the “Detailed Rules for Prevention and Control of Coal and Gas Outbursts” for coal mines, and the investigation of the residual gas pressure and content of the protected layer revealed that the protected coal seam had been mined in the upper protective layer coal face. The gas pressure dropped to 50.7% of the original coal seam gas pressure, the rate of decrease was 49.3%, the residual gas content dropped by 68.67%, and the gas concentration in the return airway was 0.31% on average, meeting the national regulations that require its value to be less than or equal to 1%. The study comprehensively demonstrates that mining of the protective layer is beneficial to the release of gas from the protected layer, and provides a practical reference for coal and gas outbursts in mines.

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“…However, when the working face is being mined back, the bottom plate is affected by the mining of the working face, and the stress is transferred to the deep part of the bottom plate of the working face of the roadway, which redistributes the stress in the rock surrounding the bottom plate. Then, there is a nonuniform stress field, i.e., a two-way unequal compressive stress field, in the rock surrounding the bottom plate, which results in different degrees of damage to the rock surrounding the bottom plate in different locations [6][7][8]. The damage to the bottom plate rock at different locations is caused by the nonuniform stress field.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Perimeter Rock Damage in a Bottom-Pumping Roadway under the Influence of Mining Activities and Rational Location Studies: A Case Study

Bai,

Wu,

Yang

et al. 2024

Applied Sciences

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With the aim of determining the damage characteristics and a reasonable positional arrangement of the surrounding rock in a bottom-pumping roadway influenced by mining in a high-gas mine, the boundary equation for the plastic zone of the surrounding rock in a circular roadway under an unequal compressive stress field was adopted to analyze the relationship between the distribution characteristics of the plastic zone of the bottom-pumping roadway and the stability of the rock surrounding the bottom-pumping roadway under different bidirectional stress ratios. This was carried out in the bottom-pumping roadway of the working face of Licun coal mine 3301 as the engineering background, where the nature of the coal seams mined is bituminous coal, and the absolute gas outflow is 0.5 m3/min−1. A numerical simulation was used to analyze the distribution characteristics of the surrounding rock stress and the bidirectional stress ratio, as well as the deformation and damage characteristics of the surrounding rock at different positions in the bottom-pumping roadway. A numerical simulation was applied to analyze the distribution characteristics of the surrounding rock stress and the two-way stress ratio, as well as the deformation and damage characteristics of the rock surrounding the bottom-pumping roadway when the bottom-pumping roadway was arranged in different locations. The results show that, with an increase in the bidirectional stress ratio, the plastic zone of the perimeter rock in the bottom-pumping roadway shows nonuniform “butterfly” distribution characteristics, which seriously affects the stability of the rock on the perimeter of the roadway; the stress on the bottom plate of the working face after excavation can be divided into four areas according to the size of the bidirectional stress ratio and the stress loading and unloading states. In addition, the size of the perimeter rock deformation can be sorted into four areas according to the damage range of the perimeter of the rock plastic zone in the bottom-pumping roadway. The size of the deformation in the surrounding rock can be sorted as follows: unpressurized high-stress ratio > unpressurized stress ratio stable area > pressurized low-stress ratio area > original rock stress ratio area. Accordingly, we found that the reasonable location of the bottom-pumping roadway is arranged at the 15 m position outside the hollow area below the coal pillar, along the limestone upper medium-grained sandstone layer along the bottom. The study’s results were applied to the field. The industrial experiments on the site show that the deformation of the surrounding rock is reasonable when the bottom-pumping roadway is dug along the limestone roof and arranged 15 m outside the fault of the mining hollow area below the coal pillar.

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Distribution law of floor stress during mining of the upper protective coal seam

Cited by 7 publications

References 45 publications

Study on overburden rock structure characteristics and surrounding rock control technology of island working face

Study on overburden rock structure characteristics and surrounding rock control technology of island working face

Study on Overburden Movement and Fissure Evolution Law of Protective Layer Mining in Shallow Coal Seam

Characteristics of Perimeter Rock Damage in a Bottom-Pumping Roadway under the Influence of Mining Activities and Rational Location Studies: A Case Study

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