Shear strength is one of the most important mechanical parameter of soil in the construction ground. It is a consequence of a friction between grains and intermolecular forces on the particle surfaces. Shear strength influences the stability of natural slopes, bearing capacity of soil, type of foundation, embankment construction time, slope inclination of the embankment, bearing capacity of piles, etc. The diploma thesis presents measurements of the drained shear strength on two materials and on a mixture of both materials in different proportions. Used materals for the experiments were sand (Fuga sand 80) and natural clay Reful, taken in the Port of Koper from the temporary lagoons, on April 2013.
All the tests were made in a direct shear apparatus. Specimens were consolidated first and then sheared at constant rate. The shear rate was calculated for each single specimen according to the standard demands.
The results of the tests were analysed and on the basis of the analysis we defined the influence of the fine grains content on the shear strength of the sand.