Abstract
The isolated island panel 10304 of the Xinglongzhuang coal mine was used as the research subject to study the deformation and damage characteristics of the coal seam floor. The damage of the floor was studied using the borehole strain sensing method and borehole imaging technology, and FLAC3D was used to study the influence of abutment pressure on floor failure. The result shows that the floor under the superimposed area which is affected by lateral and advanced abutment pressure is damaged firstly, and the maximum depth reaches 26 m, other areas of the working face about 23 m. The degree of deformation and failure of floor rock at different depths is decreased. The deformation damage increases with the advancement of the working face until a certain distance at the same depth. The hole image can clearly show the influence range of the abutment pressure in front of the coal wall and influence the degree of the advancement and lag by means of the strain increment curve for each sensor probe and the images from different drilled positions. On the basis that the results of simulation and field measurement are consistent, the results can reflect the three-dimensional failure characteristics of the whole island working face floor in the process of coal mining more comprehensively and accurately; moreover, they also can provide important information for mine flood prevention and ecological environment protection.
Highlights
Mine water inrush accidents destroy the underground construction environment and threaten the safe production of coal mines, and coal seam floor water inrush is a common type of coal mine water inrush accident [1,2,3]
Using the strain sensing method and borehole imaging technology to observe and analyze the failure deformation law of the floor during the mining process of panel 10304 in the Xinglongzhuang coal mine, the following conclusions can be drawn: (1) According to the correlation analysis between the strain test results and the borehole image, it can be determined that the depth of the floor damage is approximately 23 m during the advancement of panel 10304
The test results can provide a reliable basis for the safe mining of other working faces in the upper part of the aquifer in the Xinglongzhuang coal mine
Summary
Mine water inrush accidents destroy the underground construction environment and threaten the safe production of coal mines, and coal seam floor water inrush is a common type of coal mine water inrush accident [1,2,3]. A water inrush accident will happen if the floor damage zone communicates with the underlying aquifer when there is an aquifer in the underlying strata of the floor It is of great significance and practical application value to grasp the failure and deformation law of coal seam floors and determine the damage depth of the floors to guide safe coal mine production [9, 10]. As for theoretical analysis and calculation methods, Cai et al [11] regarded the rock mass of a floor as a semi-infinite uniform medium and, according to the law of abutment stress, proposed an analytical estimation formula for the maximum mining failure depth of the floor for a circular arch structure of overburden strata. Liu et al [13], who established a mechanical model for the failure degree of a floor based on the theory of elastic mechanics, used the matrix analysis method and the analysis of variance to determine the sensitivity of each main control factor on the depth
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