Nonlinear Behaviour of Foundation on Gravel Tire Crumb Mixture for Shallow Bedrock Sites: Fid-Bau Portal

Nonlinear Behaviour of Foundation on Gravel Tire Crumb Mixture for Shallow Bedrock Sites

Dixit, P. S. Naresh / Indudhara, G. / Kumar, A. Jithendra / Hiremath, Aniket I. / Reddy, Goutham B.

The utilization of scrap tires as the rubber material for engineering applications has received significant attention in recent years. Tire crumbs have low specific gravity, high damping ratio, high elasticity, high durability, and low compaction energy, making them a cost-effective way to consume stockpiles of scrap tires globally while promoting a cleaner environment. The primary aim of this study is to determine the energy absorption capacity of the gravel tire crumb mixture (GRM) under earthquake loads or vibrations and hence determine the optimum layer of low-cost base isolation in shallow bedrock sites. Soil samples were collected from different sites in East Bengaluru based on borehole data. Direct shear tests were conducted to determine the shear strength characteristics, energy absorption capacity, and brittleness index of GRM mixtures with percentages ranging from 0 to 40%. The results showed a sudden drop in shear until 10% of GRM was observed, followed by a gradual reduction in shear with increasing GRM percentages. Shear values after 30% of GRM began to show the shear value of rubber. The energy absorption capacity increased with an increase in confining pressure, and every 5% increase in GRM resulted in a good amount of improvement in energy absorption capacity with doubling of the confining pressure. The brittleness index increased and decreased with every 5% increase in GRM. Based on the DEEPSOIL analysis, we have found out that there is a significant decrease in the PGA observed in the various sites. In Site-1, there is a decrease in the PGA by 16.8%; in Site-2, there is a decrease in the PGA by 13.77%; in Site-3, there is decrease in the PGA by 4.04%; and in Site-4, there is a decrease in the PGA by 19.4%. (All the percentage shown is at the top of surface layer).Using GRM at foundation depth resulted in a definite decrease in PGA(g) and effective stress (kPa), which is highly desirable. It was observed that there is a decreases in the PGA about 9.05%, 9.54%, 12.96%, 23.8% for Site-1, Site-2, Site-3, Site-4, respectively, at the foundation level. The optimum thickness of GRM layer was found to be 1 m for all the sites as there is a decrease in the PGA in the range of 18.81–25.41% for varying thickness of GRM for the given sites. It is observed that further studies can be made on GRM so that it can be used as an cost-effective vibration isolation system around footing and foundation.