Industrial Support Column Stabilization at University of Tennessee
Problem
The University of Tennessee purchased an historic warehouse structure to consolidate their Facility Support Services department, which had previously been spread around various locations on campus. The 100,000 square foot building dated back to the early 1930s and had once been the site of a nationally recognized marble processing plant. The university undertook a full-scale renovation to transform the building into a state-of-the-art facility with offices, conference rooms, labs, and warehouse space. However, loose soils under the support columns had poor load bearing capacity. That challenge, along with the condition of the nearly 100-year old foundation, combined to create a difficult situation for the construction firm contracted to transform the warehouse.
Analysis
No drawings or other information were available about the existing foundation system. Site investigations revealed poor foundation conditions and undersized foundation elements. The subsurface exploration showed extremely variable subsurface conditions, with many areas of poor soils with low bearing capacity. To adequately support the code-required building loads, the load bearing capacity would need to be increased to approximately six kips/square foot. Alternatively, a deep foundation system would need to be added to transfer the building loads to refusal.
Solution
The design team initially conceived that they would support each of the 142 column locations by removing the slab, excavating to expose the foundation, installing helical piers, connecting them to the foundation, and then backfilling and re-pouring the slabs. However, after budgeting the proposed work and performing a constructability analysis, it was determined that this approach would be cost prohibitive and have a major negative impact on the construction schedule.
URETEK was contacted to evaluate the project and determine if its zero-excavation solutions could possibly be a good fit. After site visits, conceptual budgeting, and a review of historical project examples, the contractor’s design team decided that URETEK’s soil stabilization methods would get the job done in less time and within the project’s budget.
Result
The work was performed successfully in increments over six weeks. The URETEK Deep Injection® (UDI) process was utilized to stabilize the concrete foundation and support columns without excavation or demolition. Four injections per column at multiple depths were performed around and below the 142 column footings. With this technique, URETEK was able to effectively stabilize the warehouse, displace soft soils, increase the bearing capacity to code requirements, and prevent future settlement. The client saved time and an estimated $380,000 in repair costs by utilizing URETEK’s repair methods as opposed to the originally proposed alternatives.
URETEK is proud to have been able to help the University of Tennessee and Johnson & Galyon Construction with this impressive project. The entire warehouse remodel was completed in Spring of 2016, and since completion there have been no indications of settlement.
URETEK Deep Injection® (UDI)
Widely referenced throughout our industry, UDI involves the injection of structural polymer into base and subgrade soils to increase the load bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the pavement structure to depths determined by site-specific analysis. Our URETEK 486 Star® material flows easily into voids and weak zones within the soil mass below. Through a controlled chemical reaction, the expanding polymer compacts surrounding soils and applies a controlled pressure on targeted areas of the affected pavement above. If needed, a multi-injection design plan is utilized to gently return the pavement to its original grade. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service.
URETEK 486 Star®
URETEK 486 Star® polymer is a two-component, high-density, expanding thermoset polyurethane system. It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing buried infrastructure. URETEK 486 Star® is environmentally inert, non-toxic, and resists underground water erosion or weakening due to its industry-leading hydrophobic properties.
