North Georgia Medical Center Expansion
This project consisted of an expansion of the existing North Georgia Medical Center, including a 12-story tower with a rooftop helipad, 455-space parking deck, and 40,000 square-foot energy facility. An extensive, complex shoring wall design and installation was required to achieve final grades for both the 12-story tower and the energy facility. For the 12-story tower this included a 30-foot cut adjacent to the existing hospital building which required tiebacks to be drilled below the foundation of the existing building. In addition, the energy facility was cut into an existing 2:1 slope with an approximately 40 foot grade change, and then connected to the new tower via a utility tunnel that crosses beneath an existing entrance roadway to the hospital.
United Consulting utilized state-of-the-art technology to install an automated monitoring system to track subsurface movements behind the constructed shoring walls. For the 12-story tower the automated monitoring system consisted of an inclinometer installed within the 3-foot-wide area between the existing hospital building and the shoring wall. This wall allowed the grade to be lowered 30 feet to the finished floor elevation for the hospital tower. Micropiles were then installed to support the connection of the proposed tower to the existing building. Two more inclinometers were also installed at the energy facility directly behind the shoring wall and within the existing 2:1 slope, with one location near the corner of the shoring wall that intersects with the facility connecting utility tunnel.
Shape array accelerometers (SAAs) with two-foot sensor spacings were installed within the inclinometer casings and connected to data loggers which collect data around the clock, reporting it hourly, for the duration of nearly 3-years of monitoring. The data loggers wirelessly transmitted the data in near real-time to a project website where it was processed into engineering units. In the event of a positional change of the inclinometer beyond allowable levels, alarms were immediately sent to the project team via email and text message.
The automated monitoring system alerted the team immediately when movements exceeded very small deflection tolerances, allowing the team time to modify their construction means and methods so that the construction could safely proceed. The wall design-build team continued to keep track of the wall deflections based on their field activities to verify that the movement is within acceptable tolerances. The client was very satisfied with the ability to view the data on the website in near real-time for such a critical area of the site. Especially when compared to inherent delays receiving data from the conventional manual survey of the shoring wall that was performed by others. The 2-foot spacing of the SAAs also allowed the automated data to be directly compared to manual inclinometer readings (obtained prior to installing the sensors) which validated both the magnitude and direction of the automated data. This provided redundancy to the overall monitoring system program required by the owner, and an added level of confidence in the advanced precision of the newest technology being used for the automated monitoring system.
