DEEP INJECTION SOIL STABILIZATION
Wells Fargo Bank
The new problem was now causing the interior floors to crack, and there were concerns that the free standing vault in the center of the building, may also settle.
The bank wanted to minimize any potential damage to the recent remodel, and disruptions to daily services was not an option. Suggestions to remove and replace all the settlement areas would have closed the branch down for weeks.
Foundation Technology was contacted to survey the problems, and come up with a repair that was cost effective, and did not disrupt daily operations. We had the geotechnical report from the previous foundation repair of a few years back, so we already knew the soils analysis was a very sandy loam.
It was determined that polyurethane foam deep injection, would provide the stability and volume needed to support the interior floors, while allowing the floor and daily operations to remain intact.
Plumbing repairs were made, and Foundation Technology agreed to perform all repairs after hours.
GPR mapping of the voids was completed to aide in determining the starting points for injection. It was determined 1,100 square feet of floor area needed to be lifted and stabilized with deep injection foam. 5/8’s inch holes were drilled at 2 ft. intervals, being careful to intersect with all grout seams on the recently installed floors. Carpeted areas were removed.
Results
16,000 lbs. of HMI 402 Deep Injection polyurethane foam was eventually injected through 250 rods placed in the concrete. Injection rods were inserted to seven feet and three feet respectively in each hole. Approximately 30 lbs. of foam was injected through each rod. The foam expands quickly to fill and compress the sandy soil, increasing the bearing capacity substantially. An added benefit; the foam creates a water block against potential soil erosion.
Additional HMI 402 foam was injected directly underneath the slab to fill the voids and lift it back to level.
The project was completed in five days. holes were filled with epoxy and grout to match existing. All protection and debris removed, and the site left cleaner than we found it.
While our crew was onsite, they measured the floor elevation for potential settlement to check on the piers we had installed two years prior.
As we suspected, nothing had moved. The client was happy to know this, and has recommended us on other projects.
