Abstract
In the process of coal mining, when the buried depth is large and the loose layer is thick, the ground subsidence tends to be abnormal, thus causing great damage to the surface ecological environment. In order to reveal the mechanism of mining ground subsidence under ultrathick loose layer, taking 1305 working face of a mine as the background, the law of mining ground subsidence under ultrathick loose layer was analyzed through field measurement. The law of bedrock subsidence is analyzed by similar simulation test, and the role of ultrathick loose layer in bedrock subsidence is quantitatively analyzed. The hydrophobic settlement model of ultrathick loose layer is established by settlement theory calculation, and the law of ground subsidence caused by hydrophobic of ultrathick loose layer is analyzed. The results show that the ground subsidence is mainly composed of bedrock subsidence and hydrophobic settlement of ultrathick loose layer. The maximum ground subsidence measured in the field is 4.201 m, the bedrock surface subsidence obtained by the simulation test of similar materials is 3.552 m, and the subsidence of ultrathick loose layer obtained by hydrophobic settlement analysis is 0.58 m. Adding the subsidence of bedrock surface and the subsidence of ultrathick loose layer, the ground subsidence is 4.132 m. It is in good agreement with the total ground subsidence measured in the field, which verifies the rationality that the ground subsidence mainly includes bedrock subsidence and hydrophobic settlement of ultrathick loose layer.
Highlights
IntroductionThe balanced stress state in surrounding rock was broken, and the overlying strata began to move from bottom to top
After coal seam mining, the balanced stress state in surrounding rock was broken, and the overlying strata began to move from bottom to top
The movement law of bedrock is analyzed through the similarity simulation test, and it is concluded that when the range of moving rock strata extends to the top of the model, the water in the ultrathick loose layer will gradually percolate to the bottom rock strata along the crack
Summary
The balanced stress state in surrounding rock was broken, and the overlying strata began to move from bottom to top. Experts and scholars have established a variety of ground subsidence prediction models for coal seam mining, including prediction models based on mechanical properties of overlying strata, prediction models. Based on the above analysis, the existing prediction models of surface subsidence mainly predict the final settlement state of the ground, while the quantitative analysis of deformation laws of bedrock and loose layer in overburden is rarely studied. It can be seen that in the study of mining ground subsidence under the ultrathick loose layer, experts and scholars pointed out that the hydrophobic settlement of loose layer is one of the main aspects leading to ground subsidence. The proportion of hydrophobic settlement of ultrathick loose layer in ground subsidence is quantitatively analyzed, which provides a basis for surface subsidence control
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