Abstract:

To address the issue of spontaneous coal combustion caused by air leakage from fissures, grouting is commonly employed to seal fissures. PSES is a new type of air-leakage plugging material, whose durability and reliability of sealing performance depend directly on its intrinsic failure process. Uniaxial compression experiments, in conjunction with a single-hole model, the semi-empirical M-T model, and the CDP model, were employed to investigate the mechanical behavior of PSES across micro-, meso-, and macro-scales. The results reveal that at the microscale, the inner wall of the vesicle constitutes a primary weak point within the PSES structure, and the critical external pressure signifies the onset of localized yielding; at the mesoscale, the semi-empirical M-T model accurately predicts the equivalent effective modulus and confirms its capability to characterize the relationship between porosity and stiffness; at the macroscale, the porosity-corrected CDP model accurately fits the stress-strain curve, with the Mean Absolute Percentage Error (MAPE) ranging from 0.23% to 2.69%. Furthermore, the corrected damage factor closely corresponds with the material's actual condition, effectively characterizing its damage evolution characteristics. This, in turn, provides a reliable basis for evaluating the long-term service performance of the air-leakage plugging material.

Key words: phosphogypsum-based self-produced gas expansion slurry (PSES), spontaneous combustion of coal, mechanical model, porosity, Mori-Tanaka (M-T) model, concrete damaged plasticity (CDP) model