Experimental study on mitigation of earthquake hazards using geosynthetics

In this study, it is aimed to experimentally evaluate the effectiveness and robustness of an applicable, low-cost alternative seismic isolation (SI) system valid for low-rise and mid-rise buildings. This alternative SI system is comprised of a geotextile laid over a geomembrane located within a soil profile beneath the structure with a cylindrical shape. Because of involving geotechnics in contrast to conventional SI, proposed alternative SI system is named as Geotechnical Seismic Isolation (GSI). To obtain results that are more reliable, and to observe soil structure behavior during the excitation, an experimental setup was developed. For this purpose, a laminar box and 1:10 scaled building models were constructed. The effectiveness of the proposed GSI system was assessed by comparing the response of performed shaking table experiments with and without utilizing proposed alternative SI system. Effects of the number of the story of the building, horizontal length to depth ratio of geosynthetics, type of geosynthetics and ground motion characteristic on GSI system were investigated. Due to the curved shaped nature of the geosynthetic layer, permanent slips are diminished by the restoring effect of the gravitational forces of the isolated soil and structure mass. The comparative results of experiments revealed that GSI system could reduce the horizontal accelerations, horizontal drifts, Arias intensity, base shear, and base moment of the building. By using the proposed GSI isolation system, seismic energy transmitted from ground to structure is dissipated through slip displacement between geotextile and geomembrane. Noticeable reductions due to proposed GSI system can improve the resistance capacity of the structures against strong ground motions.