Investigating the Effect of Particle Size, Granulation and Concrete Block on the Behavior and Shear Strength of Granular Soils, with Emphasis on the Shear Zone

The particle size of granular soils have a great effect on their shear behavior. The purpose of this article is to investigate the shear behavior of granular soils with different particle sizes. The large-scale direct shear tests are conducted in three parts. The first part of the experiments is related to 4 types of granular soil with different particle size. The second part is related to the tests performed on composite samples and in the third part, the effect of a concrete block on the shear strength of granular soil is investigated. According to the results, as the particle size of the material increases, the push of the shear failure increases and the sample has a higher shear strength, in the same way, as the size of the particles increases, the friction angle of the materials and the dilation angle increases. The main finding of this article is that the materials located in the shear zone have a great impact on the strength of the sample. In composite samples, if the sand is compacted in the shear zone, although the top and bottom of the sample is gravel, the behavior and strength of the sample is close to that of pure sand. The thickness of the shear zone is dependent on the size of the particles, the thickness of the shear zone increases as the grain size increases. The concrete block in the shear zone increases the shear strength and internal friction angle of the sand sample.