The topic of this final thesis is the determination of the shear strength parameters of sand using a direct shear apparatus. The experiments were carried out on samples of uniformly graded sand used as a part of scientific research project "Physical modelling of landslide remediation constructions behavior under static and seismic actions" (ModLandRemSS). The tests were carried out at normal stresses ranging from 4 to 120 kPa to determine the shear strength parameters of the material representative of the small-scale 1g slope models tested under laboratory conditions, where the maximum geostatic effective stresses are limited by the dimensions of the downscaled models, as well as for the conditions relevant for real-size slopes. The experiments were carried out on fully saturated samples whose density corresponded to the conditions of the small-scale physical slope models. In the interpretation of the results, i.e. in the determination of the parameters of the Mohr-Columb strength criterion, given the low values of the confining stresses at which the samples were sheared, the influence of the resistance occurring in the device itself was taken into account, as well as the influence of the hydrostatic pressure existing on the shear surface of submerged samples. The thesis presents the theoretical basis of soil shear strength and the influence of effective stresses on soil shear strength, focusing on non-cohesive soils. The direct shear apparatus used in the study (GDS Instruments) and the basic characteristics of the material tested are then presented, and the installation of the samples and the testing procedures are described. The results are presented and interpreted in the last chapter and conclusions are drawn, focusing on the shear strength properties of sand under low confining stresses.