Case History: Overcoming Geological Challenges with a Unique Excavation Support System in an Urban Environment-Paper

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The University of Pittsburgh’s Victory Heights Arena and Sports Performance Center was built in a tightly constrained urban site above the remains of a former football stadium. Its deep excavation—up to 75 feet—required a permanent tied-back soldier-beam wall that temporarily supported the ground and later provided lateral restraint for the arena’s concrete perimeter walls.<br /><br />Subsurface conditions included variable fill and residual soils, sedimentary bedrock, and an extensively mined coal seam. Investigations and construction drilling encountered intact coal, mine voids, and weak mine gob, including beneath adjacent residence halls. These conditions complicated soldier-beam installation and tieback anchoring, while the team also had to avoid existing foundations and utilities and account for building surcharges.<br /><br />The design-build approach combined conventional top-down excavation on the eastern side with a less typical sequence on the west. There, soldier beams were installed from an existing-grade bench, fill was placed behind them in controlled lifts, and tiebacks were initially stressed to a lower load. Once filling and tieback installation were complete, anchors were restressed to their final loads before excavation continued downward. Defined fill-control zones helped manage wall movement and construction loading.<br /><br />The completed support system included 115 soldier beams and 400 corrosion-protected, rock-socketed tiebacks. In mine-hazard areas, steel casing protected tieback free lengths, and concrete grouting strengthened weak or voided zones so excavation could safely proceed. Monitoring of the wall and nearby residence halls supported construction control.<br /><br />The project demonstrates how early design assistance, close coordination, and adapting to real-time geological findings can reduce safety, cost, and schedule risks. Integrating temporary shoring with the permanent building structure also reduced downstream construction costs while meeting the arena’s design requirements.

Keywords

University of Pittsburgh

Victory Heights Arena

Sports Performance Center

soldier-beam wall

tieback anchors

deep excavation

mine voids

coal seam

design-build construction

urban site engineering