Abstract
Coal-measure mudstone is a typical dual-porosity media, and grouting in a matrix system is dominantly controlled by the imbibition effect for silica sol. This paper studies the imbibition effect using mudstone in the Huaibei mining area and silica sol as grouting material as an example. Groutability, driving force, and diffusion difficulty affecting the imbibition effect were tested by a mercury porosimeter, nanoparticle size analyzer, optical contact-angle measuring device, surface tension meter, and rotary viscosity meter. After finely grinding a mudstone sample, a pressureless imbibition process was conducted through nuclear magnetic resonance equipment for 216 h to study colloid spontaneous migration and phase characteristics. Results show that silica sol absorption rate follows a power function and that the spectrograms of T2 are distributed in a triple peak pattern, with a tendency to move to the right of vertex time. The paper lays a theoretical and experimental foundation for field grouting in the coal mine.
Highlights
Coal-measure mudstone has low bounding strength and developed micropores
Where Cp is the specific capacity; p is pressure (Pa); t is time; kint is the intrinsic permeability of the where Cp is the specific capacity; p is pressure (Pa); t is time; kint is the intrinsic permeability of the porous medium; kr is the relative permeability; μ is the fluid’s dynamic viscosity (Pa·s); ρ is the porous medium; kr is the relative permeability; μ is the fluid’s dynamic viscosity (Pa·s); ρ is the fluid density; g is acceleration of gravity; D is the coordinate of vertical elevation (m); and the subscripts g and a indicate grout and air, respectively
Because the imbibition effect of silica sol in coal-measure mudstone is related to time and the Because thearea, imbibition effect of silica solrate in coal-measure is related to time and the contact surface the silica sol absorption can be definedmudstone as the quantity of silica sol increase contact surface the silica can in beFigure defined in the unit time area, and unit area. sol Testabsorption results arerate shown
Summary
Coal-measure mudstone has low bounding strength and developed micropores. When invaded by underground water through a dynamically developed fracture system, it showed nonlinear large deformation and significant creep characteristics. Many engineering practices (Figure 1) showed that grouting was an effective technology for fundamentally utilizing and developing the bearing capacity of surrounding rock, and was a key measure to prevent the degradation of mudstone by water. Funehag studied how the penetration length of silica sol in a fracture system sand columns [10,11]. Funehag studied how the penetration length of silica sol in a fracture system can be computed analytically both as a 1-D channel flow and a 2-D radial flow [12]. Using mudstone in the Huaibei mining area and silica sol as the grouting material as an example, this paper studies the imbibition effect of silica sol in coal-measure mudstone matrix. Groutability, this paper studies the imbibition effect of silica sol in coal-measure mudstone matrix.
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