The Application of Soil Nailing Support in Boston’s Big Dig Tunnel

Big Dig Tunnel is located in Boston, the east of America, closing to the coast of the Atlantic. Its scale is the largest, cost is the most, project time is the longest and the difficulty is the largest in American history. It began to construct in 1991 and basically completed in 2006, there are still some tail-in work at moment.

The purpose of Big Dig Tunnel is to replace the Elevated Road in Boston and eliminate the influence of noise and pollution. The whole project is divided into 50 parts and the deepest can reach 120 feet. The most difficult part lies under the Fort Point Channel. Engineers had to construct 6 rectangle-shaped working places and then grout cement.

The project of Big Dig Tunnel includes underground road, bridge, slope and tunnel. It planned to protect old streets and construct during normal working hours of a day, so someone called it “operating heart surgery on a sober patient”. There were also difficulties appearing constantly, such as water seepage, cement board collapse, etc. So soil nailing support is necessary in this project.

Soil nailing support is a simple method to reinforce project. Under the action of soil gravity, the main function of soil nailing support is to stabilize partial soil of working place and avoid it falling down or being eroded.

The completion of Big Dig Tunnel means a hope for Boston. The dark parking lot under Elevated Road has been replaced by parks and the buildings in the shadow of Elevated Road has saw the sun again. The average time of passing through Boston has shortened from 19.5 minutes to 2.8 minutes, traffic condition has promoted largely and the emission of carbon oxide has decreased. This project gave ground space back to city and developed an integrated urban corridor with residence, business and afforest. It reconstructs a space link among city, sea and people.