Fine Numerical Simulation Study Of Pebbly Slip Soil About Triaxial Shear

Slip soil of most landslide contains coarse particles. Its composition can include gravel, sand, clay and so on. Soil-rock-mixture exhibits a high degree of heterogeneity on the spatial structure, which makes the research on its physical and mechanical properties difficult. With the development of computing technology, numerical analysis and rock and soil mechanics, it’s inevitable that to conduct the structural mechanics research of soil-rock-mixture based on numerical analysis techniques.By using CT scanning, digital images of particle distribution in triaxial test sample of slippery gravel were obtained., Based on these images, numerical models were built and analyzed to reveal the movement of the gravel and fine grained soil of the slip soil during shearing process as well as the stress state of fine-grained soils on the surface of gravel. The main results are as follows:(1) By using image processing techniques, the fabric of gravels was reconstructed with digital CT slice images. The established three-dimensional model reflects the actual structure of the sample with gravels after the amendment. And a method of describing for gravel space status was put forward.(2) Numerical meshing method of two-dimensional and three-dimensional pebbly soil slip model were studied. The fabric characteristics of gravel before and after the test was digitized.(3) Compared with the CT images, the effects of fabric characteristics of gravel, such as the gravel size, orientation of long axis, spatial distribution and gravel content, on shearing zone were analyzed using two-dimensional numerical simulations to find the relationship between the shear zone and gravel fabric features. It was found that the shear zone is controlled by the fabric characteristics of gravels.The gravels near shear zone, especially the flat gravels and those with its long axis perpendicular to the shear zone trend aligned along the shear zone during shearing. Gravel content is the most significant factor on triaxial strength, which is also the key factor of the shear failure zone. With comparison with CT images, cracks usually first appear on the gravel-soil interface which is the weak part of slip soil. (4) Refined3D numerical simulation was conducted on pebbly slip soil sample to acquire its deformation and strength characteristicsas well as the movementof coarse particles and fine particles. the failure mechanism of pebbly slip soil was analyzed.. Compared with the CT image, triaxial shearing properties, especially the stress and deformation of pebble slip soil can be revealed by refined3D numerical simulation.