Foundation Retrofit of Three Structures Utilizing Micropiles

Micropiles are an economical foundation solution for projects that have access constraints and low headroom conditions. Conventional piling techniques can be expensive or even impossible in these types of situations when foundation upgrades are required. Micropiles have been used to retrofit existing foundations due to under design of existing foundations or to upgrade existing foundations for added load. This paper will discuss three case studies where micropiles were used to retrofit existing buildings. The first project is a parking garage in Lake Highland, Texas, where 36 micropiles were used to remediate 12 of the existing failed parking garage column piers. The second project is a fifty-plus year-old building in downtown Dallas, Texas, that involved the conversion of an existing basement into a parking garage. It required 5 micropile to underpin an existing wall footing that was to be undermined for ramp construction and 6 additional micropiles to support three new wall columns created within an existing wall to allow the passage of cars. The third project was the expansion of an existing coliseum, micropiles were used in combination with structural bracing and permanent soil nails. The new foundations were installed within the project schedule and will provide long-term support for all applied foundation loads.