Centrifuge modeling of geotechnical mitigation measures for shallow foundations subjected to reverse faulting

Surface fault ruptures are particularly damaging to buildings, lifelines, and bridges located across or adjacent to active faults. These structures should be designed in consideration of surface fault rupture hazards or strategies should be adopted to protect the structures from fault-induced damage. Geotechnical mitigation strategies such as diversion of the fault rupture away from the structure and diffusion of the rupture over a wide zone are possible strategies. The effectiveness of these geotechnical mitigation measures for reverse faulting on shallow embedded foundations was investigated using a series of centrifuge tests. These measures included excavation of a vertical trench adjacent to the foundation and installation of geogrid layers beneath the foundation. The trench was shown to be effective for a range of foundation positions depending on the magnitude of the fault offset, dip angle of the fault, depth of the trench, embedment depth of the foundation, and the number of trenches used. The geogrid layers prevented a distinct fault rupture from reaching the surface and spread fault displacement over a wider zone, but were unable to mitigate the surface fault rupture hazard for shallow embedded foundations.