Experimental and numerical analysis of waste tire and geotextile reinforced retaining walls

In the thesis study, research was conducted for model retaining walls consisting of backfill material waste tire crumbs (ALK) and geotextile reinforcement. In the experimental study, granular waste tire crumbs (ALK) were used in the clay floor as backfill material in the amount of 0-10-20-30%. Vertical loads were performed for the strip foundation system on model retaining walls for 0, 10, 20, 30% amounts of ALK and 30% ALK+geotextile reinforcement as backfill material behind the retaining wall. For these mixtures, the optimum water contents were obtained by using the Harvard mini compaction tool as 16.2, 15.9, 15.2 and 14.1% respectively. In the cutting box experiments conducted for mixtures, the cohesion values for the 0, 10, 20, 30% amounts of ALK were obtained as c=66.88, 27.0, 20.88 and 12.74kPa, respectively, and the internal friction angle values were 30, 11.30, 18.260 and 27.70, respectively. As the ALK percentage in clay soil increases, the soil acquires granular properties, while the cohesion values decrease, the internal friction angle values increase. In laboratory scale model experiments; reinforced concrete retaining wall was manufactured in laboratory environment according to scaling rules. In laboratory-scale loading experiments, loading was performed on backfill material behind the retaining wall until a horizontal displacement of about 5 mm was formed at the peak of the retaining wall. For 0ALK%, 10ALK%, 20ALK%, 30ALK% and 30ALK%+ geotextile reinforcement mixtures, the stresses applied at these deformation values were 25kPa, 35kPa, 40kPa, 40kPa and 50kPa. According to the experimental study results, the optimal amount of ALK to be used in clay floor was in the December of 20-30%. For the backfill material condition with the addition of 20% ALK, a bearing capacity of about 60% is provided better than pure clay. In the case of a backfill material with the addition of 30% ALK + geotextile reinforcement, a 25% increase in the carrying power capacity was achieved compared to the case with a backfill material with only 30% ALK addition. Geotextile layers have met the tensile stresses formed on the ground and reduced horizontal deformations. Analyses were performed using the Plaxis 3D program on the model retaining walls for all mixtures. Results close to the values obtained in model loading experiments have been obtained with Plaxis analyses. According to the analyses performed with Plaxis, the best performance for backfill material was obtained for 20-30% ALK content. Adhering to the principles of scaling, the values obtained in laboratory experiments performed on model retaining walls and the horizontal deformation and bearing capacity values obtained in analyses performed with Plaxis coincide with each other. According to both laboratory experiments and Plaxis analyses, the optimal percentage of waste tires was obtained in the December of 20-30%.