Laboratory study of Soil Slopes Reinforced with Waste Tire Based on Horizontal Displacement

In recent years, the number of waste tires around the world is increasing rapidly and has become an environmental and economic problem. Today, accumulation of waste tires in the environment is one of the biggest problems to the environment and recycling waste tires is the best strategy to solve this problem. The use of waste tires in construction and geotechnical projects is one of the effective strategies in this regard. In this paper, experimental tests of earth slope reinforced with waste tires based on horizontal displacement (25 experiments) has been performed. During incremental loading, digital images were taken from the models and the particle image velocity (PIV) method was used. Parameters such as tire layer length, number of layers and tire layer position are considered as variable. The results show that the use of tire reinforcement has a significant effect on reducing horizontal displacement under the foundation and slope surface. Horizontal tire rows are the best reinforcement location in terms of improved bearing capacity and lateral displacement. When four layers of 60 cm long reinforcement tire are placed in the upper half of the slope, the bearing capacity increases 3 times and the lateral displacement under the foundation decreases by 3.1 times. When three layers of tires with a length of 60 cm are placed in the upper third of the slope, the bearing capacity increases by 2.3 times and the lateral displacement under the foundation increases by 1.3 times. When six, eight, and nine layers of reinforcing tires with a length of 60 cm are placed into the slope, lateral displacement under the foundation is reduced more than 3.5 times. In Iran, eight largest tire factories produce 13.5 million tires in a year. It also imports 4 million tires a year. Therefore, 17.5 million tires are the annual consumption of the country. More than 100,000 tires are the product of factory production line waste, as well as used tires. Waste tires have been used to strength retaining walls, foundations, improve soil properties, embankments and etc. Therefore it is believed that soil reinforced with waste tires become a wider application in the future, especially in countries with low worker costs. In this paper, the test was performed in a box with length, width and height of 2, 1, 1 m, respectively. The test material used in this study is sand in the dry state. The maximum and minimum dry sand densities are 19.43 and 16.36 kN/m, respectively. Internal friction angle and cohesion were measured by direct shear test at 38 degree and about 0 kPa, respectively. Digital images taken from the front of the test box during the experiment. Images were processed using GeoPIV software developed at the University of Cambridge. The results of this study are as follows:1. The best position in terms of bearing capacity and lateral displacement is to use four layers of reinforcing tire in the upper half of the slope.2. As the length of the reinforcement layer increases, the bearing capacity increases significantly and the lateral displacement decreases. Especially when the length of the reinforcement tire is 60 cm and the length of the reinforcement passes through the rupture wedge, the improvement in bearing capacity and lateral displacement of the foundation is noticeable.3. The best position in the three layers of reinforcement tire on the slope in terms of bearing capacity and lateral displacement is one-third of the upper slope.4. The presence of a tire in the lower third of the slope has little effect on improving the bearing capacity, lateral displacement of the foundation and the slope surface compared to the slope without reinforcement.