Experimental Investigation of Grading, Shape Factor and Compaction Effects on Anisotropic Permeability of Coarse Grain Solis

The permeability is one of the most important physical properties of a soil that has been used in geotechnical engineering. Soil permeability generally depends on several factors, such as soli properties containing the porosity, surface roughness of solid particles, Saturation and fluid (water) properties which passes through the soil. In order to do the research a testing device is designed for measuring horizontal and vertical permeability of the coarse particles. In this study, four uniform soil samples and three non-uniform samples with different compactions are selected and tested under various water heads. The results show the permeability in the horizontal direction is often greater than the permeability in the vertical direction and this difference in non-uniform sample is greater than that in uniform samples. The permeability anisotropy ratio for uniform samples is between 0.85-1.35 and for non-uniform samples is between 1.32-3.5. Also, with increasing the uniformity coefficient the rate of anisotropy permeable decreases.