Search Results (2)

Underground reservoirs are a key technology for storing mine-impacted water resources, and the long-term stability of their coal pillar dams in high-stress environments is critical. The long-term safety of coal pillar dams in such reservoirs is closely related to creep and water seepage phenomena. To better illustrate this phenomenon, internal expansion coefficients and porosity blocking coefficients are proposed in this study to characterize how water affects the evolution of permeability in water-bearing coal samples. A novel model is developed to capture the interaction between matrix and fractures and the influence of creep deformation on permeability in water-bearing coal samples. Triaxial creep–seepage experiments are conducted on raw coal samples with varying moisture content. The results show that volumetric strain values and strain rates increase with rising effective stress during creep and show a tendency to first increase and then decrease with the increase in moisture content. Additionally, permeability consistently decreases at each stage of creep. Model parameters are determined through the nonlinear least squares method, and the reliability of the permeability model is validated based on experimental data. Both theoretical modeling and experimental results indicate that water seepage–creep coupling significantly affects the long-term strength of coal samples in a high-stress environment, and corresponding prevention and control measures are suggested. This study can provide a scientific basis and guidance for the study of long-term operational destabilization damage of coal mine underground reservoirs to ensure the safety of the structure. Full article

Through laboratory simulation experiments, this paper studies the influence of different temperature and stress conditions on strain changes of raw coal samples induced by the CO₂ adsorption with tri-axial creep-seepage and adsorption-desorption experimental system. Comparing and analyzing the experimental results, the study shows that: (1) within a certain time, the axial and radial strain of the raw coal sample induced by CO₂ adsorption both show a growing trend as the adsorption time increases and the strain of the raw coal sample for CO₂ adsorption is obvious anisotropy; (2) at the same point in time, the greater the axial effective stress, the smaller the axial strain increasing rate of the loaded coal sample during CO₂ adsorption process and the smaller the value of axial deformation; (3) during the adsorption process, the volume strain of raw coal sample decreases with the increasing of temperature, namely, the adsorption capacity of raw coal sample decreases with the increasing of temperature. Full article