Szukana fraza: [Abstract = "The results reveal that the friction angle values for the planar sandstone, shale\-sandstone, and shale are 31.28 \[degress\], 21.1 \[degress\], and \[degress\], respectively. These findings, combined with the shear stress\-strain behavior, suggest that the interface \(shale\-sandstone\) is primarily influenced by the shale characteristics rather than the sandstone characteristics. Hence, it is important to consider failure along the interface when analyzing critical conditions, particularly in slope failure scenarios."]