Phoenix Project #2019
A short distance from Worcester’s Union Station, an existing concrete crib wall supporting the railroad right-of-way was well beyond its service life. The deteriorating section was approximately 250 feet long and a maximum of 30 feet tall. A permanent soil nail system (SNS) with shotcrete was chosen to stabilize and repair the existing wall.
An initial 4-inch layer of reinforced shotcrete was applied to stabilize the face of the crumbling wall. Next, Phoenix would utilize its Casagrande C-9 drill rig to install rows of soil nails through the newly-stabilized wall face. The C-9 was chosen for its ability to reach nail locations as much as 14 to 15 feet above existing grade elevation. The nail installations were supported by two laborers in a mobile elevated work platform.
Before commencing any production drilling, two sacrificial nails were installed and tested to verify design assumptions. After successful completion of these tests, a total of 120 permanent soil nails were installed. All nails had studded bearing plates that were attached to the face of the shotcrete wall, and which would accommodate the attachment of the permanent wall’s reinforcement. Vertical forms were constructed for panel expansion and to ensure an 8-inch layer of shotcrete would be placed. The shotcrete was screeded flat and a finish layer was applied leaving an aesthetic that neither caught the eye, nor was an eyesore. It masterfully blended into the landscape and looked as strong as it was unassuming.