Verification of Jet Grouting for Structure Rehabilitation: Fid-Bau Portal

Verification of Jet Grouting for Structure Rehabilitation

Haider, Tarek F. / Byle, Michael J.

Verification of jet grouting to stabilize an existing stone masonry abutment by increasing the abutment's bearing area and mass was necessary to assure proper performance. Project constraints such as: maintaining bi-directional vehicular traffic over the bridge, maintaining uninterrupted rail traffic under the bridge, maintaining and protecting eight underground utility lines through the work, and ensuring safety of the bridge abutment, the roadway and nearby structures from the high-pressure grout limited the techniques and verification methods available. The jet grouting created a soilcrete mass to enlarge the existing abutment by overlapping individual grout columns interlocked with the existing stone masonry. The jet grouting was completed under continuous full-time observation by the design engineer to verify compliance with the intent of the project specifications. To verify that the grouting was not damaging to the existing structures, the abutment, roadway and sidewalk were instrumented to continuously monitor movement during jet grouting. Test columns were constructed prior to production grouting using feeler pipes to assess grout coverage, column diameter and select the proper jetting pressure, grout flow rate and monitor extraction speed. Core samples were taken to verify the integrity and properties of the soilcrete. Laboratory density and compression tests were performed on selected core samples of the soilcrete. All tests exceeded project requirements. The core borings through the soilcrete mass met the project's core quality requirements and demonstrated the effectiveness of the jet grouting despite some unanticipated rubble in the abutment backfill.