Study on the rule of roof moment and surface subsidence about shallow-buried coal seam under thin base rock

2013 ◽  
pp. 531-534
Author(s):  
Baoyang Wu ◽  
Zhenhua Ouyang
Keyword(s):  
Coal Seam ◽  
Surface Subsidence ◽  
Base Rock

scholarly journals Study on Numerical Simulation Test of Mining Surface Subsidence Law under Ultrathick Loose Layer

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Weiping Shi ◽  
Xiaocheng Qu ◽  
Chuntao Jiang ◽  
Kaixin Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Coal Seam ◽  
Crack Propagation ◽  
Research Process ◽  
Surface Subsidence ◽  
Stress Evolution ◽  
Seam Mining ◽  
Loose Layer ◽  
Similar Simulation

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.

scholarly journals The Prediction Model of Super Large Subsidence in High Water Table Coal Mining Areas Covered with Thick Unconsolidated Layer

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yueguan Yan ◽  
Weitao Yan ◽  
Jibo Liu ◽  
Junting Guo
Keyword(s):  
Coal Seam ◽  
Soft Rock ◽  
Simulation Software ◽  
Surface Subsidence ◽  
Thickness Ratio ◽  
Lagrangian Analysis ◽  
Ratio Increase ◽  
Rock Stratum ◽  
Maximum Surface ◽  
Subsidence Prediction

In mining engineering, after the extraction of underground resources, the maximum surface subsidence is usually less than the mining thickness of coal seam. However, under the condition of thick loose layer, some special phenomena appear in surface subsidence, for example, the maximum surface subsidence value is greater than the mining thickness of coal seam. This special phenomenon cannot be predicted by traditional subsidence prediction methods. To solve this problem, by using the numerical simulation software Fast Lagrangian analysis of continua (Flac), we study the changing rules of subsidence with different strata lithology and unconsolidated layer thickness and reveal the formation mechanism of this law. The results show that the effect of the thick unconsolidated layer on the hard rock is greater than that of the soft rock. When the rock is soft, the unconsolidated layer moves as a whole following the bedrock during the whole mining process. The surface subsidence decreases approximately linearly with the thickness ratio increase of the unconsolidated layer to bedrock. However, when the rock is hard or medium hard, there are supporting structures formed inside the rock stratum, which has supporting effect on the overlying strata. The surface subsidence undergoes three proportional sections, first increases, then decreases, and finally increases with the thickness ratio increase of the unconsolidated layer to bedrock. Combined with these laws, based on the theory that the rock strata space can be completely compressed gradually, we derive the calculation method of surface subsidence under the condition of thick unconsolidated layer and apply it to practice. The results show that the prediction results are consistent with the actual situation and meet the engineering requirements. The research results can provide a reference for the subsidence prediction of similar conditions.

Finite Element Analysis of the Subsidence of Cap Rocks during Underground Coal Gasification Process

2013 ◽  
Vol 859 ◽  
pp. 91-94
Author(s):  
Xiao Xiong Zha ◽  
Hai Yang Wang ◽  
Shan Shan Cheng
Keyword(s):  
Finite Element ◽  
Coal Seam ◽  
Coal Gasification ◽  
Feasibility Studies ◽  
Element Model ◽  
Numerical Results ◽  
Surface Subsidence ◽  
Underground Coal Gasification ◽  
Element Analysis ◽  
Gasification Process

This paper discusses the possible surface subsidence and deformation of the overlying rock during the underground coal gasification (UCG) process, which is an important part of feasibility studies for UCG operations. First coal seam roof movement and surface subsidence in the shallow UCG process were simulated by a finite element model coupled with heat transfer module in COMSOL. Numerical results from this model were compared with and in good agreement to the existing studies. This was followed by the development of model for deeper coal seam cases. The comparison of the numerical results from two models shows that surface uneven settlement in deep underground coal gasification is only 7% of that in shallow underground coal gasification.

Study on Deformation of Tunnel with Underlying Coal Mining

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.

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

Geofluids ◽  
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.

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

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
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.

scholarly journals Research on Key Factors Influencing Surface Subsidence of Paste Backfilling Mining in Thick Coal Seam of Deep Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Meng Zhang ◽  
Hui He ◽  
Xin Jin ◽  
Yonglong Qu ◽  
Hongjun Guo
Keyword(s):  
Coal Seam ◽  
Reference Value ◽  
Field Research ◽  
Surface Subsidence ◽  
Systematic Research ◽  
Solid Waste Disposal ◽  
Key Factors ◽  
Thick Coal Seam ◽  
Deep Mine ◽  
Key Factor

The research on the key factors of surface subsidence in paste backfilling mining of thick coal seam in deep mine is a complex system engineering, which involves mining, backfilling, support, subsidence, safety, and other aspects. At present, there is no systematic research on the key factors of surface subsidence in paste backfilling mining of thick coal seam more than 6 meters in a deep mine. In this paper, field research, laboratory experiments, theoretical analysis, and other research methods are used to carry out the research about 3# coal seam under buildings in the Lu’an area. The main conclusions are as follows: through the construction of the fuzzy extension model of surface subsidence in paste backfilling mining, five types of surface subsidence are obtained, including overburden structure, roof subsidence before backfilling, nonbackfilling account, the strength of filling body, and backfilling technology. It is the key factor to control the surface subsidence; the optimization measures are given to provide a reference for the reasonable design of paste backfilling mining in other working faces. The research conclusion has a certain reference value for solving a series of problems such as coal resources under buildings, solid waste disposal, controlling strata and surface movement, improving the recovery rate of mine resources, and extending the service life of mine.

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