GEOSYNTHETICS FOR EARTHQUAKE HAZARD MITIGATION

Geosynthetic or related materials placed under foundations can absorb seismic energy, and hence transmit smaller levels of excitation to an overlying structure. This concept of using geosynthetics as foundation isolation can be a cost-effective way of mitigating earthquake hazards to civil engineering structures. The authors have been exploring the suitability of various synthetic materials for the purpose of foundation isolation. The dynamic interface properties of these materials are being investigated using a shaking table to identify the most promising material for this application. To demonstrate the technical feasibility of using synthetic materials for foundation isolation, shaking table tests were performed. A single-story building model was placed on the shaking table and its response to harmonic and earthquake motions was measured. The accelerations and story drifts of the model building with and without foundation isolation were measured. The results from these tests demonstrate that using geosynthetics as foundation isolation reduced the column shear forces in the building model by as much as 70%. Associated with this reduction are slip deformations along the geosynthetic interface ranging from 1 to 10 cm depending on the earthquake record and its intensity.