Experimental study of deformations and failures of the coal wall in a longwall working face

Tian, Maolin; Han, Lei; Xiao, Heng; Meng, Qinglin

doi:10.1016/j.engfailanal.2021.105428

Cited by 19 publications

(8 citation statements)

References 25 publications

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“…After the destruction of the direct roof of the coal seam during the primary mining, the overlying rocks in the entire mining area are damaged and deformed, and the collapsed rocks of the overburden rocks fill the mining void area, and the surface is deformed to a certain extent. The ruptured rocks of the lower coal seam damaged by secondary mining will cause the overburden rocks to continue to collapse and fill the mining void area so that the gap between the rocks destroyed by the primary mining will be closed gradually, which increases the surface movement and deformation compared with the primary mining [14][15][16][17][18] .However, when the accumulated mining thickness reaches a certain amount, the gap inside the rock formation will be gradually compacted and will no longer increase with the mining operations. The number of repeated mining is related to the lithology of the overburden rock on the roof.…”

Section: Theoretical Analysismentioning

confidence: 99%

Study on the Law of Surface Subsidence in Layered Mining of Thick Coal Seam with Medium Hard Roof

Liu

Wei

Tan

et al. 2023

Preprint

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The thick coal seam carried out by layered mining, the influence range of the overlying rock layer is relatively larger than that of the single-layer mining, and the surface deformation is more intense. At present, the research of thick coal seam mining is mainly concentrated within 15m, and there are relatively few studies on coal seams with a cumulative mining thickness greater than 15m. In order to study the surface sinking law of coal seam mining with a cumulative mining thickness greater than 15m, this paper takes the Mengba as the research object to simulate the change of the surface sinking coefficient after layered mining under the condition that the thickness of the medium hard roof plate and single-layer mining is 5m. In order to verify the correctness of the model, the simulation results are combined with the measured data after the first and second layers of the 1210 working surface of the surface observation station, and the maximum relative error between the simulation results and the measured results was 2.7%, which was less than the specified limit difference of 5%.It shows that the surface sinking coefficient q of stratified mining has the characteristics of segmentation. When the cumulative mining thickness is less than 25m, q is positively correlated with the mining thickness. When the cumulative mining thickness is greater than 25m, the q value will tend to be a fixed value and will no longer change with the increase of mining thickness. Finally, the calculation formula between the ground subsidence coefficient and cumulative mining thickness of layered mining under the condition of medium-hard roof is fitted,which provides a parameter basis for the mining of coal seams in similar mines.

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Section: Theoretical Analysismentioning

confidence: 99%

Study on the Law of Surface Subsidence in Layered Mining of Thick Coal Seam with Medium Hard Roof

Liu

Wei

Tan

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Confining pressures seriously affect mining safety. [24][25][26] The coal seams and overlying rocks is also affected by cyclic loading, such as roadway excavation, as shown in Figure 1. The mechanical properties, energy evolution characteristics, and stability of the coal seams and overlying rocks will change under the action of confining pressure strength and cyclic loading.…”

Section: Introductionmentioning

confidence: 99%

Effect of confining pressure strength on the characteristics of energy evolution and fatigue fracture of the coal‐rock structural body

Li,

Yue,

et al. 2023

Fatigue Fract Eng Mat Struct

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The stability of coal seam‐overlying strata is significant to the safety of coal mines. The coal‐rock height ratio and confining pressure strength affect the stability of coal seam‐overlying strata. The research purpose of this paper is to obtain the effects of confining pressure and coal‐rock height ratio on the mechanical properties, energy evolution characteristics, and damage variables of structural body through the uniaxial loading, uniaxial cyclic loading, and triaxial cyclic loading experiment. Based on the evolution characteristics of the energy, the concept of energy dissipation ratio is put forward, and the effect of height ratio and confining strength on the energy dissipation ratio are compared and analyzed. The research results of this paper can provide theoretical reference for exploring the stress and energy evolution of coal seam‐overlying strata during chamber excavation and working face mining.

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“…The result indicated that yield degree and yield distance were the main controllers on the roof failure which could occur in front of the longwall face or over goaf area. An experimental study by Tian et al [9] on the fracture and deformation of the working coal face by considering non-uniform bearing pressure area shows that the coal wall goes through a complex fracturing phenomenon which is directly linked to distance from the coal face. Most of the surface fracture in coal face is tensile, while shear or combination between the two can be found further away from the face.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Roof Stability in Longwall Face Developed in Shallow Depth under Weak Geological Conditions

et al. 2022

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Developing longwall mining under weak geological conditions imposes a substantial challenge with regard to the higher risk of falling roofs. Maintaining the stability of the longwall face in this aforementioned condition is crucial for smooth operation. Investigating roof conditions in longwall requires detailed study of rock behavior in response to a few key influences. This paper presents the outcome of a numerical analysis of roof stability in shallow depth longwall face under weak geological conditions. A series of validated FLAC3D models was developed to examine the roof condition of the longwall face under the influence of shield canopy ratio, shield resistance force, and stress ratio. The results show that these three key factors have a significant impact on longwall roof conditions, which can be used to optimize its stability. Two distinct mechanisms of the roof caving behavior can be observed under the influence of stress ratio. The countermeasures of reducing face-to-tip distance and cutting width are proposed to improve the roof condition of longwall face under weak rock. The outcomes show a substantial improvement in roof conditions after adopting the proposed method.

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Experimental study of deformations and failures of the coal wall in a longwall working face

Cited by 19 publications

References 25 publications

Study on the Law of Surface Subsidence in Layered Mining of Thick Coal Seam with Medium Hard Roof

Study on the Law of Surface Subsidence in Layered Mining of Thick Coal Seam with Medium Hard Roof

Effect of confining pressure strength on the characteristics of energy evolution and fatigue fracture of the coal‐rock structural body

Numerical Investigation of Roof Stability in Longwall Face Developed in Shallow Depth under Weak Geological Conditions

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