Abstarct: Improvement of problematic Soils and improvement of its engineering specifications such as bearing capacity, shear strength, and soil permeability can be done using different methods, which is soil preparation using plastic parts with a random distribution of one of these methods. Land extracted from the sea is one of the man-made engineering phenomena that is designed to exploit more of the coastal strip and its parametric resistance must be improved by engineering methods and soil improvement. The present research is aimed at the improvement of one of the crushed land in northern Iran in Bandar-e Anzali, using the sizes of 1 × 1 cm pet beverage bottles and its percentage by direct shear test, during which the effect of the relative density of the Reinforced sample and Normal stress on the sample has been analyzed in the experiments. The results showed that with increasing relative density, the shear stress of the maximum tolerance in the tested samples increased and with increasing vertical overhead, the formation of the sample increased. At the end of the experiment, the percentage of pet and optimum relative densities were determined for the improvement of Anzali port sandy sand.