The Chesapeake Bay Bridge Tunnel’s Parallel Thimble Shoal Tunnel Project is constructing a second tunnel parallel to the original to reduce traffic congestion. All work is being performed from man-made islands in the Chesapeake Bay which are densely packed with utilities, equipment and operations facilities associated with the existing tunnel, which is in continuous use.
During previous phases, installation of sheet piling for tunneling activities and other driven elements induced consolidation of the loose sandy fill on the islands, causing settlement of duct banks, pavements and other structures, which were remedied by CJGeo using polyurethane compaction grouting.
In this case, sheet piles had to be driven immediately adjacent to the roadway in order to excavate the receiving pit for the tunnel boring machine. The construction team was concerned about inducing settlement of the adjacent roadway, so reached out to CJGeo about performing compaction grouting under the footing for the original tunnel’s portal wall, after the wall had been demolished down to grade.
CJGeo performed compaction grouting utilizing an NSF-certified potable water contact plural component polyurethane grout. Cutoff criteria was 0.10 inches of movement of the foundation or adjacent roadway. Upon completion of the compaction grouting by CJGeo, sheet piling installation started, with only nominal movement of the foundation and roadway.