Moving the historic U-505 submarine at Chicago's Museum of Science and Industry to a new exhibit hall meant uprooting the 60-year-old German submarine from the moorings cradling it since 1954 and transporting it to its new home 40 ft. below grade in the northeast corner of the front lawn of the museum's east pavilion.

The first step was making structural repairs to the submarine to ensure the World War II-era relic would survive the stress of its move, said M. Richard Klarich, Museum of Science and Industry capital program manager for Chicago-based Jones Lang LaSalle, which manages the museum's facilities and operations department.

The Jones Lang LaSalle project and development services division is the overall program manager for the U-505 Relocation and Conservation Project.

advertisement

One Last Dive

After repairs were done, the 700-ton submarine was jacked up, and self-propelled and self-jacking dollies were inserted beneath it. Once 18 sets of dollies and 144 tires were in place below the sub, the moving task began.

"It took a day to move it from its original position west of the Henry Crown Space Center around to the south side of the space center," Klarich added.

"And then it took one day to move the submarine to the east side of the space center, and that included making a 180-degree turn. We used a thick, rigid kind of a reinforced mat called DuraMat on the ground to spread the load."

In total, the submarine was moved about 1,000 ft.

The U-505 sat on the east side of the Crown Center for a few days while eight supershoring towers were prepared to lower the sub into the underground hall.

When they were complete, the submarine was taken off of its wheels.

Klarich said workers "skidded it off," using a jack and beams with a slide pad. It took a full day to slide the submarine into place and lower it the first few feet to the towers.

Then it took another full day to get it down to its final "resting place," moving it 4 in. at a time.

Each of the towers was built of structural steel, with a column of wood cribbing. "That's the way they lower it 4 in. at a time," Klarich said. "Each of those pieces of timber is 4-by-4 in., and they stack them in a pattern that allows one layer of 4-by-4 shoring to be removed from the bottom of each of the eight shoring towers" at the same time.

Bunker Mentality

Moving the submarine was just one of the tasks for Jones Lang LaSalle and the general contractor on the project, W. E. O'Neil Construction of Chicago.

Dennis Murzyn, the O'Neil project manager, said the project is budgeted at $35 million, including soft costs. It began in January 2003 and will be complete by the end of this year. The U-505 exhibit is slated to reopen in its new quarters sometime in 2005.

Once the project is done, no one at ground level will know the climate-controlled underground exhibit hall is there because it will be covered with grass and other landscape material, Murzyn said.

Created of architecturally cast-in-place concrete, the vault containing the submarine will measure 100 ft. wide and 300 ft. long and will stand 35 ft. high at the walls. It will feature an underground connecting link to the main exhibit hall at the same depth and extending about 55 ft. wide and 100 ft. long.

"That's cast-in-place concrete, too," Murzyn said. "They wanted to recreate the look of old World War II-era bunkers."

Two elevators will allow guests to travel to the exhibit floor or a midlevel mezzanine, from which they will be able to look over the submarine. A ramp winding down and around the submarine from the mezzanine will allow guests to view the sub from every angle.

"You can go into the queuing line, if you choose to go inside the submarine," Murzyn said. "Or you can go through the exhibit, bypassing the interior of the submarine. There will be a lot of interactive [displays] around the submarine on the main floor."

A Watery Depth

Perhaps the greatest problem in tackling the underground vault was its proximity to Lake Michigan.

The water table at the site is 6 ft. below grade. What's more, contractors had to work in close coordination with the nearby Lake Shore Drive reconstruction project, which includes work on an underpass at 57th Street.

The other issue was the delicate task of ensuring the Victorian-era museum structure would not be damaged due to the excavation of the link from the museum to the exhibit. The 70-year-old Museum of Science and Industry is housed in a 111-year-old building constructed for the 1893 World's Fair, also known as the World's Columbian Exhibition.

Unlike the other grand buildings of the fair's "White City," which were constructed of wood with plaster surfaces, the museum building was the only major load-bearing masonry structure in the World's Fair. It was dubbed the Palace of Fine Arts because it housed some of the world's finest works of art, and because of its masonry construction, it was the only building to survive the fair.

Murzyn said contractors installed a jet-grout column wall around and underneath the existing museum to cut off the water underneath it. With water held back, underpinning pits could be dug and poured to make excavation possible.

Micropile caps and underpinning were used to support the corner of the museum.
Micropiles were drilled down to the hardpan clay, and then caps were placed on top of the micropiles.

A post-tensioned beam 5 ft. high, 42 in. wide and 40 ft. long was placed on top of the caps on the wall's exterior. Another post-tensioned beam was installed on the inside, this one 5 ft. high, 2 ft. wide and 40 ft. long.

"They had tendons in there to post-tension it," Murzyn said. "That also helped support the building during the construction. We just hung it in air."

Once the post-tensioned beams were in place, contractors got to work on six underpinning piers, each roughly 3 ft. by 5 ft. by 40 ft. in depth. They were hand-dug and lagged all the way down.

"They would be filled with concrete, one at a time," Murzyn added. "The whole purpose of this underpinning process was so the existing building wouldn't settle."

Once these steps had been completed, a sequenced excavation was undertaken.

Meanwhile, the team was at work creating the structural concrete walls of the vault.
The walls were completed in one continuous pour.

If the walls had been designed to be vertical, as most walls are, the construction team would have had little problem. But these walls needed to slope out at an angle from the floor of the vault. The fear was that if the pour took place from above, air escaping upward would have created air pockets in the walls.

"We ended up pumping the concrete from the bottom, using pump valves and pushed the concrete up," Murzyn said.

At the top of the vault, contractors will use a combination of vaulted steel box girders and structural steel girders. The vaulted box girder will be just below grade, along with acoustical metal decking, lightweight concrete, waterproofing and geofoam fill.

Geofoam fill was used to lighten the load of earth on top of the structure. Because the top of the vault is curved, the amount of soil atop it could have varied from 1.5 ft. in the center to 6 or 7 ft. at the edges. Geofoam fill allows a consistent layer of just 1.5 ft. of soil to be placed over the entire vault, with the fill making up the varying distances from soil to vault top.