Computed tomography based numerical simulation for triaxial test of soil–rock mixture

The fabric of gravels can significantly affect the characteristics of deformation, stress field and failure of soil–rock mixture. The computed tomography (CT) was used to obtain the shape and location of gravels in triaxial soil–rock mixture samples. Based on the CT images, the typical longitudinal profiles of triaxial sample were reconstructed and the wire-frame models indicating the interfaces between the soil matrix and gravels were built through digital image processing (DIP), including image binarization, noise removal and interface detection. A mesh generator, DISTMESH was utilized to improve meshing quality, especially near the interfaces. The mesh was exported to FLAC3D using an interface program and 2D plane strain models with different gravel content were simulated for verification. It was found that cracks usually first appear on certain parts of the soil/gravel interfaces where the shear stress is prone to accumulate. The location of cracks have a good consistency with the results obtained by CT images. It can be concluded that the method proposed is efficient and accurate for the behavior analysis of soil–rock mixture by using numerical simulation and triaxial test with CT scan.