Project: Washington Middle School Evansville, IN
General Contractor: Danco Construction Co.
Micropile Installer: United Dynamics, Inc. 2555 Cannon St New Albany, IN http://www.udipdi.com 800 359 4471
Washington Middle School was being renovated and it was discovered that it was experiencing some differential settlement. Soil borings indicated the presence of fill material below the foundation. Traditional steel resistance underpinning and helical underpinning were selected originally by the design engineers as the choice of remediation. Upon review of the soil information, UDI was concerned with the capabilities of these underpinning methods due to the soils information provided. It would be possible for the helical piers to encounter cobbles/floaters in the fill thus negating the installation. The use steel resistance piers likewise could become compromised by the nature of the fill. To solve this UDI proposed the installation of small diameter hollow bar micropiles. The main advantage of the method would be the penetration of the fill material into the 'good' material below the cobbled fill.
The passive installation of the micropiles would also allow for a greater factor of safety in strength and parameters. UDI mated Titan's 40/20mm hollow bar micropiles with Earth Contact Products MP 350 Underpinning Bracket (75,000-99,000 lbs capacity) to provide a competent underpinning system. UDI excavated the site and prepared the footings during the first day of operation. Once the brackets were mounted, UDI installed the micropiles, coring and simultaneously grouting the bars as they drilled 35' through the cobbled fill and into the good strata. Upon completion, UDI’s crew was able to stabilize and lift the structure with the MP350 micropile bracketing system. By utilizing this application, UDI was able to complete the project with a three-man crew in just over three days. UDI's vast experience in dealing with different underpinning techniques provided an economical solution to an otherwise difficult situation.