Model laboratory test investigation on effect of shape parameters of granular soils on bearing capacity of soil

Generally granular soils and materials are used as geo-materials in civil engineering sector. Particles properties of soils play important role on soil strength and behavior. Some shape properties such as size of particles, shape, roughness and distribution determine engineering properties of granular soils. Ultimate bearing capacity and shear failure mechanism of soil under footing depends on some factor such as relative density of soil, shape of particles and morphologic properties of soil. At this study bearing capacity and shear failure mechanism of a model strip footing placed on a soil has been investigated at different roundness, different relative densities and different granulometry. After taking angular soil to laboratory, itwas changed to rounded and well-rounded soil by use of Los Angles machine. Later, soil with 6 different granulometry between 0.30 to 4.75 mm was gain by sieving from different sieves. Tests were done at 3 different relative densities (Dr=30%, 50% and 70%). Pictures were taken from soil during tests. Displacement of soil beneath under footing was determined by analyzing captured images with Geo-PIV program. By increasing particle size and relative density, increasing bearing capacity of soil have been seen at experimental works. At the same time by increasing roundness of soil, decreasing bearing capacity of soil was detected. From bearing capacity values, bearing capacity of soil was decreased while granular soil was changes to rounded. At the same time decreasing bearing capacity of soil continued while rounded soil was changed to well-rounded. Shear failure mechanism of granular soil was punching at relative density of Dr=30%, local at relative density of Dr=50% and general at relative density of Dr=70%. Bearing capacity of soil was decreasing at constant relative density while angular soil was going toward well-rounded and general shear failure mechanism was changing to local or punching. It found that roundness has more effect on bearing capacity of soil at bigger relative densities (Dr=70%).