Michigan Contractor Tackles New, Challenging Excavation Project

August 2011, Vol. 66 No. 8

System
Slide rail is installed simultaneously as the trench or pit is excavated. The individual component pieces can be handled with a standard size excavator which means that excavation contractors can usually install the shoring system themselves. Tri-City used a Komatsu PC 600 and CAT 330 to install the system. Inside the pit, Tri-City used a Komatsu PC 128 to dig under the posts and panels and any spots the bigger machines could not reach.

Slide rail is installed by sliding the panels into integrated rails on the posts, and then pushing the panels and posts incrementally down to grade as the pit is dug; a process commonly referred to as a “dig and push” shoring system. Slide rail is considered “active shoring” which means that personnel and equipment can be safely in the hole throughout the entire installation and removal process.

“Because we had never used slide rail before and this was the first time we had attempted an excavation of this size, there was a big learning curve for us,” admits Schmidt.

Briggs agreed. “It took a lot longer to install than we anticipated, but once we started going, it went in really easily.”

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Due to Tri-City’s inexperience with a slide rail system, a senior team of Efficiency’s slide rail installers were onsite. “That’s very typical with first time slide rail users,” says Greg Ross, Efficiency’s director of slide rail systems. “The first day, they (contractor crew) usually are intrigued on how and if it’s going to work; the second day, there is usually a bit of consternation as they have to overcome unexpected ground conditions and as they are trying to put the system in one piece at a time; but by the third day, they really get the hang of it and start to figure out that this is a great system.”

After pre-cutting the site down about five to 7 feet, Tri-City installed a 38 by 50 by 32-foot deep ClearSpan configured slide rail system. ClearSpan’s design is unique in that it shores a large excavation without any need for cross-braces. The system stays entirely open by utilizing innovative waler I-beams on the outside of the system at the top, and inside the system to prevent deflection. The walers integrate into the Slide Rail system with the use of custom brackets that slide along the posts. The inside waler brackets have rollers on the back allowing it to easily move up and down as the system is installed and removed.