Failure modes of weak interlayers with different dip angles in red mudstone strata, Northwest China

摘要

The shear mechanical behavior of weak interlayer is of great significance for the stability analysis of landslides. Based on theshear deformation-failure characteristics of weak interlayer soil and the clay damage theory, a shear failure mode is proposedto describe this kind of phenomenon. Triaxial compression tests and numerical simulation are conducted on weak-interlayersamples at conditions of different confining pressures and inclination angles. The numerical and experimental results showbasically good agreement for both the peak strength and failure patterns. With increases in the thickness and dip angle (inthe range of 0°-60°) of the weak interlayer, the shear strength of the samples decreased gradually. The weak-interlayersamples having a low dip angle were crushed and inflated; when the dip angle exceeded 15°, there was shear slip along theweak interlayer; when the weak interlayer was thin, the sample sheared along the structural plane; when the weak interlayerwas thick, there was extrusion inside the weak interlayer or shear slip along the contact surface of the weak interlayer andmudstone. These results can improve our understanding of the mechanical behavior of mudstone rock mass with weak interlayersand can be used to analyze the stability of rock slopes or other rock engineering cases such as tunneling constructionin rock mass with weak interlayers.