Liquid nitrogen (LN₂) cooling can induce significant cracking damage in coalbed methane (CBM) reservoirs. To investigate the combined effects of LN₂ cooling and bedding angles on the mechanical behaviors of bedded coal, coal specimens with different bedding angles (0°, 30°, 60° and 90°) were cooled. The variations in the surface features and P-wave velocity of the specimens were analyzed. The mechanical properties (tensile strength, peak strain and absorbed energy) were measured under Brazilian test conditions and compared. Furthermore, the crack propagation processes and the failure mechanisms were observed and compared. The results showed that LN₂ cooling can induce considerable thermal damage inside the coal, resulting in the deterioration of the coal’s mechanical properties. This deterioration led to easier cracking and a higher fragmentation degree under splitting load. In addition, the reductions in tensile strength, peak strain and absorbed energy exhibited obvious anisotropic characteristics. The thermal cracks induced by LN₂ cooling participated in the formation of macrocracks. After LN₂ cooling, the failure mode remained unchanged from that before cooling at bedding angles of 0°, 30° and 90°. Notably, a transition from mixed-mode failure (primarily caused by tensile failure) to tensile failure occurred at the 60° bedding angle. This transition caused the specimen to fail at a relatively lower load, resulting in maximum reductions in tensile strength (34.8%), peak strain (27.6%) and absorbed energy (55.0%) at the 60° bedding angle. This paper provides new insights into the LN₂ fracturing of bedded coal seams.

液氮 (LN ₂ ) 冷却可在煤层气 (CBM) 储层中引起显着的裂化破坏。为了研究LN ₂冷却和层理角度对层状煤力学行为的综合影响，对不同层理角度（0°、30°、60°和90°）的煤样进行冷却。分析了样品表面特征和纵波速度的变化。在巴西测试条件下测量机械性能（拉伸强度、峰值应变和吸收能）并进行比较。此外，还观察并比较了裂纹扩展过程和失效机制。结果表明，LN ₂冷却会在煤内部引起相当大的热损伤，导致煤的机械性能变差。这种劣化导致在劈裂载荷下更容易开裂和更高的破碎度。此外，拉伸强度、峰值应变和吸收能的降低表现出明显的各向异性特征。LN ₂冷却引起的热裂纹参与了宏观裂纹的形成。LN _{2 后}冷却，0°、30°和90°层理角度下，失效模式与冷却前保持不变。值得注意的是，从混合模式失效（主要由拉伸失效引起）到拉伸失效的转变发生在 60° 层理角度处。这种转变导致试样在相对较低的载荷下失效，导致在 60° 层合角下拉伸强度 (34.8%)、峰值应变 (27.6%) 和吸收能量 (55.0%) 的最大降低。本文提供了对层状煤层LN ₂压裂的新见解。