100 / 2023-06-15 13:52:55

Strata movement of overburden-separation grouting working face and its influence on gas emission during mining

Overburden-separation grouting; Overburden stress distribution; Strata movement; Gas emission; Gas control

Due to its excellent effect of surface subsidence reduction, the overburden-separation grouting (OSG) technology has been widely applied to the mining of coal resources buried under water bodies or buildings. However, OSG changes the laws of overburden migration and mine pressure variation, and the resultant law of relieved gas enrichment and emission in the stope remains unclear, which challenges gas control during OSG application. In view of the above problem, with the 22301 working face of Tunlan Coal Mine as an example, the deformation characteristics, stress distribution laws and stress relief zone shapes of overburden in the absence and presence of OSG were studied contrastively through numerical simulation and on-site tests. Furthermore, the law of gas emission in the stope before and after grouting was analyzed through engineering measurement. The following results were obtained: OGS changes the law of strata movement. With the rise of grouting pressure (GP), the subsidence of strata above the separation layer decreases while that below the separation layer increases gradually; the heave displacement of floor strata below the coal seam gradually decreases. OSG significantly changes the geometric shape and range of the overburden stress relief zone. As the GP rises, the gas enrichment area moves downward continuously and shrinks spatially. Horizontally, the ranges of the stress relief zone and the free space in the goaf shrink, while the range and compaction degree of the compaction area gradually grow. After OSG, the total amount of gas emission in the working face falls by 52.2%.