Meso and macroscale mechanical behaviors of soil-rock mixtures

Composed of large rock blocks and fine soil particles, the physical and mechanical behaviors of soil-rock mixtures (S-RMs) are quite complex. To develop insight into the S-RM deformation and failure mechanisms on the macro and mesoscales, CT image sequences of the samples were obtained on different stages of the S-RM triaxial test. Then, the 3D mesostructures of the samples were reconstructed based on the developed 3D Meso-Structure Reconstruction and Analysis System (MSRAS(3D)), and the algorithms required for quantitative analysis of the S-RM mesostructure were provided. The fracture and motion processes of the rock blocks in the S-RM sample were tracked based on the reconstructed 3D models. Because of the influence of the sample preparation method, the primary axes of the rock blocks trended toward the horizontal direction. This led to the initial anisotropy of the S-RM's mesoscale structure. To compare reconstructed 3D models of the samples from different test stages, three types of the rock-block breakage modes were analyzed: disintegration, fracturing, and edge-corner breakage. The tests results indicated that the influence of the rock blocks makes the S-RM stronger than soil, The S-RM p-q curve was not a straight line due to the rock block breakage. As a result, a modified Mohr-Coulomb strength relationship in the form of a power function was suggested.

Automated summary

Soil-rock mixtures (S-RMs) are composed of large rock blocks and fine soil particles, exhibiting complex physical and mechanical behaviors. This study used CT image sequences and a 3D Meso-Structure Reconstruction and Analysis System (MSRAS(3D)) to investigate the deformation and failure mechanisms of S-RMs. The results revealed the influence of rock block breakage on the strength and p-q curve of S-RMs, suggesting a modified Mohr-Coulomb strength relationship in the form of a power function.