Study on the Slurry Diffusion Law of Fluidized Filling Gangue in the Caving Goaf of Thick Coal Seam Fully Mechanized Caving Mining

Abstract

Because of the problem of gangue discharge and surface subsidence during coal mining, the current research on underground filling mainly focuses on the paste filling, solid filling, and grouting filling of the overburden separation layer after scaffolding. We proposed the technology of fluidization gangue grouting for filling the collapse area based on our previous research. The prediction method of residual space in the collapse area and the diffusion law of gangue fluidization filling slurry are two essential points for successfully implementing the technology and maximizing the use of goaf for gangue backfilling and reducing overburden settlement. To further explore the remaining space distribution law of the collapsed goaf in thick seam fully mechanized top coal caving mining and the effect of coal gangue fluidization filling, the caving goaf of the 3307 fully mechanized top coal caving face in Sangshuping No. 2 coal mine in the Weibei mining area was detected by the transient electromagnetic method. We studied the distribution law of the measured abnormal area in the caving goaf, which reflects the distribution law of the remaining space from one aspect. The coefficient of the remaining space was calculated to be 19.5%. Then, we applied COMSOL simulation software. The diffusion law of coal gangue fluidized slurry in the caving goaf was simulated and analyzed. It shows that the most obvious diffusion direction of the coal gangue slurry is the trend of the gradual expansion of the “cavity pore” multi-type residual space, indicating that with the increase in the diffusion distance, the diffusion resistance gradually increases, and the slurry morphology gradually presents the “claw” form. According to the space theory and fractal dimension theory, the prediction method of the remaining space in the caving goaf is given, and the design basis of the filling drilling parameters is determined. Finally, the field-filling test was carried out. The results show that the high- and low-level fluidized filling in the caving goaf can safely and efficiently handle the gangue in the mine, and the residual space characteristics and slurry diffusion law in the caving goaf are consistent with the above. The research results provide theoretical support for the fluidization filling technology of coal gangue in thick seam fully mechanized top coal caving areas.

Hydro-Mechanical Coupling of Cement-Based Slurry Grouting in Saturated Geomaterials

“…For the slow-flowing slurry in geomaterials, the momentum due to inertia is negligible [1,[9][10][11][12]. Meanwhile, the momentum exchange owing to the mass transfer of slurry to solid phase is also considered small and is neglected, having the same order of magnitude as the inertial momentum terms.…”

“…However, three-dimensional or in situ tests are more suitable for evaluating cement-based slurry grouting implemented in fieldworks [4]. Scholars have proposed many numerical Mathematics 2023, 11, 2877 2 of 14 analysis [5][6][7][8] or analytical methods [9][10][11][12][13][14][15] to explore the migration mechanism of cementbased slurry grouting in geomaterials. The common disadvantage of these models is that they cannot reflect the hydro-mechanical dynamic coupling between the force acting on the solid skeleton of geomaterials and the migration of suspended slurry particles.…”

Study on the diffusion and deposition law of pore slurry in gangue filling zone based on CFD-DEM coupling

“…Understanding the distribution law of remaining space is important for filling effects. He simulated coal gangue slurry diffusion in goaf using COMSOL simulation software and found that “cavity-pore” multi-type residual spaces gradually expand [ 4 ]. In addition, researchers have also studied the effects of major fissures in fracture networks and slurry viscosity on diffusion, developed dynamic water-injection grouting simulation experimental devices for fractured rock masses.…”

Strata Movement of Gangue Grouting Filling in Subsequent Space for Coal Mining and Analysis of Its Practical Effects

“…2 Well and Huangling No. 2 Well [37,38], and there is no relevant research on shallow buried and kilometer mine. When the GGFSS is applied in the mine with different buried depths, the suitable grouting hole layout is different.…”