COMPARISON OF PREDICTED VERSUS OBSERVED STRUCTURAL DISPLACEMENTS OF EXISTING STRUCTURES AT THE PORT OF MIAMI

摘要

The Port of Miami Tunnel Project is currently being constructed near downtown Miami, Florida to relieve congestion downtown due to port related traffic. The project consists of twin bored tunnels excavated by a hybrid Tunnel Boring Machine (TBM) within complex mixed face conditions beneath existing surface structures located on Dodge Island. Several structures were identified as critical within the zone of influence and were considered to be sensitive to ground settlements induced by the tunneling operation. Complex three-dimensional and two-dimensional finite element analyses were conducted incorporating the twin-TBM tunnels and existing Dodge Island structures. The effects of the TBM tunneling and the behavior of the structures due to the tun-neling-induced ground settlements were explicitly modeled. This provided structural displacements which were compared to the respective capacities of the elements to evaluate the potential of damage to the structures. Accordingly, building elements were highlighted which were most sensitive to ground movements and were closely monitored. The results of the numerical modeling assured the owner that tunneling could be undertaken without the use of additional measures such as ground improvement or underpinning of the structures prior to the TBM reaching Dodge Island. Extensive instrumentation was installed on the existing structures and data was evaluated daily throughout the tunneling to ensure the structures were performing as predicted. A thorough comparison of observed structural displacements to predicted movements shows that the Dodge Island structures performed as or better than expected and validated that the structures were only affected within the range of permissible limits.