To elucidate the influence of bedding angle and chemical corrosion under acidic environment on the mechanical behavior of carbonaceous slate, intact rock samples were collected from the sidewalls of a large-deformation roadway. Triaxial compression tests were performed on slate specimens subjected to different bedding angles and varying durations of acid-induced chemical corrosion. A continuous-discontinuous coupled numerical model based on the combined Discrete Element Method (DEM) was developed. Extended numerical analyses under additional loading conditions were conducted using an improved flexible membrane radial loading technique, with the analyses being validated by physical test results. The results indicate that: (1) Bedding angle significantly influences both the failure modes and peak strength of carbonaceous slate. The peak strength initially decreases and then increases as the angle between the bedding planes and the loading axis grows, reaching its minimum value at 15°~45°. This behavior is mainly attributed to wing crack propagation induced by shear slippage and localized stress concentration at these angles. (2) Acidic chemical corrosion markedly accelerates the structural degradation of the slate, with the peak strength decreasing by 36%~44% after 90 days of erosion, thereby confirming a negative correlation between chemical erosion and mechanical damage. (3) The DEM-based continuous-discontinuous coupled numerical model with flexible membrane radial loading accurately reproduces the triaxial mechanical response of the specimens under extended conditions, thereby providing a theoretical basis and data support for the stability evaluation and support design of deep roadways.