Big Dig: differenze tra le versioni

Versione delle 16:21, 22 nov 2009

Versione delle 18:07, 22 nov 2009

Riga 36:

Reworking such a busy corridor without seriously restricting traffic flow required a number of state-of-the-art construction techniques. Because the old elevated highway (which remained in operation throughout the construction process) rested on pylons located throughout the designated dig area, engineers first utilized slurry wall techniques to create 120 ft.-deep concrete walls upon which the highway could rest. These concrete walls also stabilized the sides of the site, preventing cave-ins during the excavation process.

The multilane interstates also had to pass under South Station's 7 tracks which carried over 40,000 commuters and 400 trains per day. In order to avoid multiple relocations of the train lines while the tunnelling advanced, as had been initially planned, a specially designed jack was constructed in order to support the ground and tracks to allow the excavation to take place below. Ground freezing was also implemented in order to help stabilize the surrounding ground as the tunnel was excavated. This was the largest tunnelling project undertaken beneath railway lines anywhere in the world. The ground freezing enabled safer, more efficient excavation, and also assisted in environmental issues, as less contaminated fill needed to be exported than if a traditional cut and cover method had been applied.[19]-->

Un altra difficoltà era rappresentata da un tunnel preesistente che attraversava il tracciato dell'autostrada sotterranea. Per costruire muri di supporto è stato necessario scavare sotto il tunnel e costruire un ponte sotterraneo in cemento armato che supportasse il peso del tunnel.

Other challenges included an existing subway tunnel crossing the path of the underground highway. In order to build slurry walls past this tunnel, it was necessary to dig beneath the tunnel and build an underground concrete bridge to support the tunnel's weight. -->

==Note==