A New Theoretical Method to Predict Strata Movement and Surface Subsidence due to Inclined Coal Seam Mining

In the process of coal mining, the surface subsidence under ultrathick loose layer is abnormal (subsidence coefficient greater than 1.0), which will cause great damage to the surface ecological environment. The fracture propagation and stress evolution of bedrock are of great significance to the prevention of surface subsidence. Taking the 1305 working face of a mine as the background, this paper study the process of crack propagation and stress evolution of bedrock under the influence of ultrathick loose layer by methods of on-site measurement, similar simulation, and numerical simulation. During the research process, the physical model was verified by the measured data. Then, the numerical model was verified by the crack propagation angle and subsidence of bedrock, which were obtained in a similar simulation. Based on the verified numerical model, it was obtained that after the coal seam was mined out, the bedrock above the mined-out area was mainly damaged by tension, while the strata on both sides of the crack expansion angle were mainly damaged by shear and tension. During coal seam mining, for bedrock the process of fracture expansion, subsidence, and stress evolution all could be divided into four stages. This research provides a basis for the control of surface subsidence.

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Study on Mountainous Shallow-Buried Coal Seam Mining Working Face Strata Behaviors and Overlying Strata Movement Features

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.2911 ◽

2011 ◽

Vol 121-126 ◽

pp. 2911-2916

Author(s):

Guo Lei Liu ◽

Ke Gong Fan ◽

Tong Qiang Xiao

Keyword(s):

Coal Seam ◽

Horizontal Displacement ◽

Simulation Software ◽

High Rate ◽

Strata Movement ◽

Working Face ◽

Element Simulation ◽

Valve Opening ◽

Seam Mining ◽

Overlying Strata

Through testing the mountainous shallow-buried coal seam mining working face strata behaviors in Faer mine field, it got the strata behaviors: it was of large roof pressure, high rate of safety valve opening in hydraulic support, and even some supports crushed or took separation between top beams and tail beams. Traditional method of calculating supports’ resistance can not be applied to mountainous shallow-buried coal seam mining working face. With the discrete element simulation software UDEC it analyzed the strata movement feature, and got that the overlying strata took collapse and horizontal displacement after mountainous shallow-buried coal seam mined, and the strata movement feature was different between reverse slope mining and positive slope mining.

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Method to Calculate Mining-Induced Fracture Based on the Movement and Deformation of Overburden Strata

Shock and Vibration ◽

10.1155/2021/9965466 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Guo-sheng Xu ◽

Hui-gui Li ◽

De-hai Li ◽

Yan-bin Zhang

Keyword(s):

Coal Seam ◽

Burial Depth ◽

Empirical Methods ◽

Fractured Zone ◽

Strata Movement ◽

Probability Integral Method ◽

Movement And Deformation ◽

Probability Integral ◽

Seam Mining ◽

Overburden Strata

Mining-induced fracture of overburden strata is intimately related to underground water disasters in coal mining. In this work, we develop an analytical model that uses the probability integral method to calculate the subsidence of the subsurface and the overburden strata. In the developed model, according to the failure characteristics of the mining-induced strata, the horizontal deformation of the strata is expressed by the tensile rate of the elastic plate’s neutral plane to reflect the degree of fracture initiation and expansion. The distribution of the water-flowing fractured zone (WFZ) in the overburden strata is calculated by substituting the probability integral function of overburden strata movement into the equation of layer tensile rate. The panel 31071 in Peigou coal mine is taken as a case study, and the height of the water-flowing fractured zone (HWFZ) is determined by the proposed method. Conventional empirical methods and the proposed method are used to predict HWFZ in panels with mining schemes, and the results show that the model is particularly advantageous for inclined coal seam mining where the inclined mining size gradually increases and the coal seam burial depth gradually decreases. In such kind of situations, the overburden strata movement and deformation intensify and the mining fracture develops further with the progress of mining, a feature considered poorly by conventional empirical methods but well represented in the proposed method.

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Study on Deformation of Tunnel with Underlying Coal Mining

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.105-107.1295 ◽

2011 ◽

Vol 105-107 ◽

pp. 1295-1298

Author(s):

Zhi Gang Yan

Keyword(s):

Numerical Simulation ◽

Coal Seam ◽

Coal Mining ◽

Calculation Method ◽

Surface Subsidence ◽

Mining Technology ◽

Deformation Law ◽

Coal Block ◽

Dip Angle ◽

Seam Mining

Coal mining can cause the strata distortion and surface subsidence. With infrastructure construction scale in our country enlargement, the case of approaching excavation caused by coal mining is increasing and more complicated. The calculation method of current regulations is too simple and don't conform to the present coal mining technology, so it will cause serious waste of resources. By using numerical simulation, this paper regards the influence of coal mining on the above tunnel as approaching excavation problem and studies the tunnel deformation law with three different coal mining mode. Based on the analysis and calculation, this paper proposes measures to ensure that the coal seam mining and tunnel's safety. The result indicates the more smaller the dip angle of coal block the more larger the displacement and the deformation range of tunnel. The most effective method for decrease deformation is the backfill method. If the conditions are permitted, backfill method is the preferred method and longwall caving method is last.

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Simulation Analysis of Influencing Factors of Subsidence Based on Mining under Huge Loose Strata: A Case Study of Heze Mining Area, China

Geofluids ◽

10.1155/2020/6357683 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Xianxiang Zhu ◽

Wenquan Zhang ◽

Zaiyong Wang ◽

Chenghao Wang ◽

Wei Li ◽

...

Keyword(s):

Coal Seam ◽

Simulation Analysis ◽

Soil Layer ◽

Soft Rock ◽

Mining Area ◽

Simulation Software ◽

Surface Subsidence ◽

Ground Movement ◽

Hard Soil ◽

Seam Mining

Based on the coal seam mining under the condition of thick soil layer, the mechanical mining subsidence process under the condition of thick soil layer was analyzed. Combined with the results of core drilling and laboratory test in the mining area, the mechanical analysis of the special transition strata of “hard soil-soft rock” at the bottom of the soil layer was carried out. Additionally, the characteristics of the shallow buried soil layer were compared and analyzed. Furthermore, the significance of this transitional font to the surface subsidence law was proposed. By using the numerical simulation software of FLAC3D and choosing the thickness of “hard soil-soft rock” transitional font as the influencing factor, a model was established and the surface subsidence characteristics of different stratum combinations were numerically simulated. The research results show that the transitional font is the special strata indicating that the hard soil is transiting to the soft rock, having a significant effect on the ground movement and deformation induced by coal mining. It cannot be designated into the loose strata. Also, it cannot be regarded as the bed rock to study the influence of it on the surface subsidence. The “hard soil-soft rock” transitional font has the support effect on the overlying strata during coal seam mining, which can restrict the surface subsidence. Furthermore, the larger the thickness of the transitional font is, the more obvious the restricting effect of it on the surface subsidence is. Meantime, this restricting effect will not be changed with the variation of the proportion between the loss bed and the bed rock thickness. Only the restricting extent is a little different.

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Dynamic Changes in Surface Damage Induced by High-Intensity Mining of Shallow, Thick Coal Seams in Gully Areas

Advances in Civil Engineering ◽

10.1155/2020/5151246 ◽

2020 ◽

Vol 2020 ◽

pp. 1-16 ◽

Cited By ~ 1

Author(s):

Jianwei Li ◽

Xintian Li ◽

Changyou Liu ◽

Xiangye Wu

Keyword(s):

Coal Seam ◽

High Intensity ◽

Three Dimensional ◽

Surface Damage ◽

Surface Subsidence ◽

Dynamic Changes ◽

Thick Coal Seam ◽

Amplification Ratio ◽

Geological Disasters ◽

Seam Mining

This study proposes a novel approach to study the mechanism of mining and dynamic changes in surface subsidence and geological hazard-prone regions caused by shallow, thick coal seam mining in gully areas. This approach combines field observation, three-dimensional modeling, numerical simulation, and theoretical analysis based on the conditions of the Chuancao Gedan coal mine. The in situ stress field of coalbeds is influenced by the gully terrain. Shear stress becomes concentrated on the surface, causing geological disasters such as landslides and collapse of gully slopes. High-intensity mining activities increase the concentration and are more likely to cause such geological disasters. The influence area and severity vary dynamically with the expansion of the excavation area. With the continuous expansion of coal seam mining, the amplification ratio η (the ratio of the maximum impact range of surface subsidence and the mined-out area) first increased to 3.35, then decreased, and finally reached a constant value of 2.1. The principle of road line selection is proposed based on an analysis of surface subsidence and gully slope stability on the goaf edge. The principle of subsection reinforcement of the gully slope under the dynamic influence of coal seam mining is also determined.

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