Influence of Grain Size Coarse Soil on Shear Strength

The geo- mechanical behavior of coarse soils is difficult to grasp by geotechnical methods , mainly due to the presence of large elements that disrupt or prevent the tests . Our work presents a study of the mechanical behavior of two coarse soils of different types namely Tuff MEKKEDRA and crushed gravel SIDI ALI- Benyoub west of Algeria by observing the effect of the size of diameters of the grains on the shear strength. Two aspects are considered. The first relates to a state of the art parameters which have a direct influence on the shear strength of coarse material . The second part concerns a presentation and analysis of the results of direct shear tests of materials prepared for Optimum Proctor. It is noted that the grain size affects in a significant way the properties of the shear strength. The bigger the diameter, the greater the angle of friction is important. However, the cohesion decreases with increasing grain size