GCG was engaged by the Client to provide advice on the ground conditions and selection of geotechnical design parameters so that a new design could be implemented, and comprehensive monitoring installed. Full-time site supervision was provided by GCG to enable rapid interpretation of the monitoring results and validation of the new design.
GCG was closely involved in evaluating the seismic design considerations for the tunnels and has direct experience of the performance of tunnels in two previous earthquakes (magnitudes 7.4 and 7.2). Aspects of earthquake design included the collection of dynamic and small strain soil parameters, the mapping and assessment of faults and their activity, and the design of tunnels incorporating dynamic loads with special construction details to limit potential damage.
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