Geotechnical Mitigation Research Articles

Simulation of the Interaction of Micropiles and a Fault Rupture

Understanding the cause of structural damage and loss caused by surface faulting rupture requires research on the fault rupture-foundation interaction and geotechnical mitigation methods. The present study investigated the interaction of reverse-faulting surface rupture and a foundation system comprising a mat foundation and micropiles. The effects of the micropiles on the rotation of the foundation and rupture propagation was examined for different interaction mechanisms. The results suggested that the response was sensitive to the position of the foundation micropiles. It was found that the position of the foundation-micropile system relative to the rupture determined the type of interaction between the soil, rupture, micropiles, and foundation, which is significant for development of geotechnical mitigation methods.

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.

Geotechnical Mitigation Strategies for Earthquake Surface Fault Rupture

AbstractSurface fault rupture can be damaging to structures built on or near active faults if the hazard is not addressed properly. Fault-induced angular distortion and lateral ground strain can cause beams to yield and eventually lead to structural collapse. When avoidance is not possible, geotechnical mitigation strategies can be used. These strategies include spreading fault displacement over a large area, causing the structure to respond with rigid-body movement, and diverting the fault rupture around the structure. The effectiveness of these strategies can vary from protecting life safety to preventing significant damage and can be effective for a range of dip-slip fault displacements. Earth fills should be sufficiently thick and ductile to prevent the underlying fault dislocation from developing at the ground surface. Thick RC mat foundations proved to be especially effective in shielding the superstructure from the damaging effects of the underlying ground movements. Although more challenging to im...

Engineering management of lifeline systems under earthquake risk

The state-of-the-art of lifeline system management under earthquake risk is discussed. After a historical overview and specific features of lifeline earthquake engineering, elements of lifeline earthquake engineering practice are presented. They include outline of lifeline protection technologies, lessons from recent urban earthquakes particularly Kobe 1995, and seismic code developments. Then two topics are addressed specifically. First seismic reliability under system interaction is discussed with its general scheme and an analytical methodology. Next, criteria for lifeline performance is discussed with an emphasis on quantification of qualitative issues that are needed particularly in implementation processes. After presenting a general framework, two cases, one from Kobe on water customers' response, and one from California regarding funding procedure for seismic improvement. Finally, future orientations of earthquake engineering and its relation to lifeline earthquake engineering is addressed. It is emphasized that we should establish a third generation earthquake engineering where structural and geotechnical mitigation, crisis management, and sustainable development should be integrated through multi-disciplinary developments. Some examples of multi-disciplinary research initiatives are introduced.