Ground Subsidence and Surface Cracks Evolution from Shallow-Buried Close-Distance Multi-seam Mining: A Case Study in Bulianta Coal Mine

Self Cite

Mine fires are becoming a serious issue as the intensity of mining increases, especially in deep mines. Loose coal gob has a hidden ignition location and a high possibility of spontaneous combustion, which makes fire prevention difficult. Therefore, based on the theory of gas seepage and the characteristics of loose coal, a model of air leakage and spontaneous combustion in gob is established in this paper. Using working face #10414 in the Yangliu coal mine as an example, the relationship between the three spontaneous coal combustion (CSC) zones and the three stress zones is analyzed and verified by combining a FLAC3D simulation with field monitoring. In addition, the influence of advancing speed on the CSC is discussed, and suggestions for fire prevention are presented. The results show that the variation in the calorific value of the CSC with increasing degree of looseness of the residual coal in the gob forms an arch‐shape. There is a one‐to‐one relationship between the distribution of the three stress zones and the three CSC zones. In addition, as the advancing speed increases, the contact time between the loose coal body and the air decreases and the possibility of CSC decreases. This study provides a scientific basis for fire prevention and control in mines.

Section: Analysis Of the Resultsmentioning

confidence: 99%

Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob

Shu

et al. 2019

Self Cite

“…With the increasing intensity of coal mining, coal seams with favorable geological structure and shallow depths are diminishing continuously. In recent years, miners have had to overcome the challenge of coal extraction from close‐distance coal seams at many mining regions . A number of studies have already been performed to resolve the issues encountered during the mining of close‐distance coal seams.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, miners have had to overcome the challenge of coal extraction from close-distance coal seams at many mining regions. [8][9][10][11][12][13][14] A number of studies have already been performed to resolve the issues encountered during the mining of close-distance coal seams. In these studies, the thickness of strata between close-distance coal seams is over 8 m. The numerical calculation is a commonly used method to study the stress distribution law and rock movement in close-distance coal seams (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Study on the movement characteristics of the overlying stratum and surrounding rock control in ultraclose coal seams: A case study

Zhu¹,

Yao²,

Xia³

et al. 2020

In Fucun Coal Mine, the average spacing between the 3upper coal seam (UCS) and 3lower coal seam (LCS) is only 6 m. In the process of mining upper coal, the lower roadway (LR), which is 60 m away from upper pillar, becomes unstable. In order to control the surrounding rock of lower roadway, a physical model experiment and a 3D numerical calculation were performed in this study. The results of physical similarity simulation experiment show that mining of longwall face in UCS will lead to fracturing of key layers at a high elevation (KLHE) far away from the coal seam. The expanded goaf area caused large‐scale fracturing and rotation of the KLHE, which resulted in significant strata pressure behavior in LR. The numerical calculation results show that the LR should be within 19 m of the coal pillar. Finally, a plan which includes a proper location and a supporting system was proposed. The feasibility of the proposed plan is verified by an industrial application.

“…With the advancement of working face, due to the function of in situ stress and self-weight, a caving zone, a fracture zone and a curved subsidence zone are generated from the bottom upwards in the overlaying strata. [1][2][3][4] Since the fractures of coal and rock mass are the main channels for fluid migration and infiltration, it is of great significance to accurately determine the water-permeable fractured zone in the overlying strata caused by mining not only to ensure the safe production of coal mining under water, 5 but also to improve the recovery rate of coal pillars and reduce the waste of coal resources. 6,7 Numerous studies have been conducted with different methods to investigate the fracture evolution law of the overlying rock strata under different mining conditions.…”

Section: Introductionmentioning

confidence: 99%

Development characteristics and field detection of overburden fracture zone in multiseam mining: A case study

Tian

Liu

Yang

et al. 2019

Self Cite

During the multiseam mining process, the overlying strata were damaged due to different mining disturbances, where a large number of fractures were produced which were the main seepage paths of gas and water, easy to cause gas or water inrush accidents. Thus, it is necessary to explore the development characteristics of the fractured zone in the overlying strata from multiseam mining. In this paper, laboratory triaxial compression tests were firstly conducted on the rock specimens subjected to different mining disturbances. In these tests, the specimen was loaded to different stress before a regular test to simulate the different damage effects on the rock strata caused by different mining disturbances. And the corresponding values of m and s could be obtained through a calculation based on the test results. Subsequently, the numerical simulation was conducted to simulate the field situation, in which the m and s values were used in the numerical model combined with the Hoek‐Brown–modified criterion, and the results show that the overburden failure height was increased with the mining disturbances from 48 to 120 m, and then, the effects of mining height and interval thickness on the development height of fracture zone were studied by numerical simulation. Finally, the leakage of roof drilling at different stages was tested and calculated in the field. The results showed that the loss of leakage drilling can directly reflect the development degree of roof cracks, and the detection results were close to the development height of the numerical simulation fracture zone. It is verified that the simulation method used in this paper is feasible and can be used as a reference for similar research.