Performance of Geo-Base Isolation System with Geogrid Reinforcement

Abstract

To mitigate earthquake-related damage to buildings, a simple alternative method to conventional base isolation techniques is to provide a geo-base isolation (GBI) system, composed of a scrap tire–sand mixture, between the base of the building foundation and the supporting soil medium. The GBI system should possess adequate dynamic stiffness and damping properties, as well as enough shear strength to resist both static and seismic loads. This study focused on the use of geogrid reinforcement to improve the bearing capacity, settlement, and rotational aspects of a shallow foundation resting on a GBI layer under static loading. Load tests were carried out on a model footing resting on GBI layer with and without geogrid reinforcement in a sand-bed tank setup. Finite-element-based numerical modeling of the footing on the GBI system with geogrid was also carried out, and the computed results were compared with those measured from the experiments. Parametric studies were carried out using the developed finite-element model to arrive at an optimum thickness of the GBI layer, number of geogrid layers, depth of placement of first geogrid, and length of geogrids. The results from the study indicate that the bearing capacity of the GBI layer can be increased up to three times by providing double-layered geogrid reinforcements with a substantial reduction in the settlement.