Strength and deformation of tailings with fine-grained interlayers

Due to the presence of fine-grained interlayer structures (usually called lenticles), the stabilities of tailings dams deteriorate. In this study, the strength and deformation of tailing samples containing fine-grained interlayers were studied by undrained tests. Based on the Coulomb theory, the slip mechanism of tailing samples was investigated. The results indicate that the stress-strain relationship of the samples that contain interlayers of large dip angles (i.e., 45 degrees or 60 degrees) is typical strain softening. The stress-strain relationship of the samples, with the interlayers dipping with small angles (i.e., 0 degrees or 15 degrees), is strain hardening. The mechanical parameters, e.g., shear strength, internal friction angle and cohesion, decrease with the increase in the dip angle of the interlayer. In tests, three different deformation patterns, i.e., bulging, slip and composite deformation, were observed from the samples with interlayers of small, large and medium dip angles, respectively (the medium dip angle is 30 degrees). The slip occurred along the interlayer plane of the samples. When the angle of the interlayer is near 60 degrees, the strength and deformation of the samples are controlled by the fine-grained interlayer. The findings of this study can provide reference for the stability evaluation of anisotropic tailing dams and other similar structures.