Abstract:
As a multiphase complex heterogeneous material, the internal pores and fissures of coal-rock significantly influence its mechanical properties, particularly exhibiting pronounced strength deterioration characteristics in creep behavior under water-rock interaction and acidic environments. In this study, coal-rock specimens with different bedding angles (0°, 30°, 60°, 90°) and high-to-width ratios (1, 1.5, 2, and 2.5) were subjected to acidic saturated treatment and creep mechanical tests, combined with digital image correlation (DIC) technology to analyze their strain field evolution and failure mechanisms. The results indicate that acidic saturation time and high-to-width ratios significantly reduce the strength of coal samples while enhancing their deformation characteristics; bedding angles affect the creep failure modes of coal samples, with crack propagation paths exhibiting complex nonlinear development patterns due to grain distribution and bedding characteristics. The uneven distribution of strain fields reveals the crack propagation and coalescence behavior of coal samples during creep loading. The research suggests that the influence of high-to-width ratios and acidic environment should be fully considered in strip coal pillar design to ensure the safety and stability of coal mining operations.