Direct shear behavior of sand and tire chips using X-ray CT and DEM simulation

One cost effective application of mixed sand with tire chips is to use them behind retaining structures as reducing earth pressure and to use its highly permeable nature of this type of materials as an agent for reducing liquefaction induced deformation. However, the precise mechanical properties of tire chips and mixed sand with tire chips have not been clarified yet. The objective of this paper is to investigate the shear behavior of tire chips and mixed sand with tire chips. First of all, the direct shear test which is one of the typical tests to obtain strength and deformation characteristic of granular materials was conducted for tire chips, sand and mixed sand with tire chips. Using X-ray CT, three dimensional behaviors of the materials were investigated without any destructions. In order to discuss the deformation and strain from the CT images, one of the common techniques on image analysis called Particle Image Velocimetry (PIV) was used. Here, the distributions of the displacement vectors, shear strain and volumetric strain were measured in each shear displacement level. These direct shear behaviors were also simulated using 3-D Discrete Element Method (DEM) and compared to the experimental results. Finally, the mechanical properties such as deformation and failure in the materials of tire chips and mixed sand with tire chips were precisely discussed based on all the results.