PERFORMANCE MONITORING FOR DEEP EXCAVATIONS-Paper

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The paper describes how real-time instrumentation and monitoring reduced construction risk during two deep-excavation projects in Atlanta. Excavations near existing buildings, roads, and utilities involve uncertainties that design assumptions cannot fully anticipate, including unexpected ground conditions, construction methods, groundwater changes, and added loads. Continuous measurements and automated alarms can reveal abnormal behavior early enough for corrective action.<br /><br />At the Cox Tower project, a 35-foot excavation was supported by soldier-pile walls and tiebacks. Monitoring detected excessive movement at a soldier pile after a tower-crane pit was over-excavated and left open. The team backfilled the pit and installed an additional tieback row. Finite-element analyses indicated that the excavation activities had substantially reduced stability; the added support improved the factor of safety. Over-excavation, rainfall, and heavy loads near the wall may all have contributed.<br /><br />Cox Tower II involved a 75-foot excavation, with nearby structures and rock blasting adding risk. Instrumentation measurements closely matched predicted wall displacement, demonstrating the value of combining modeling with field monitoring. Alarms also identified unexpected settlement at a nearby building. Investigation found cracks and a large, unplanned soil stockpile at its loading dock. Removing the stockpile helped limit further settlement.<br /><br />Together, the projects show that real-time data, predefined alarm thresholds, and rapid communication enable teams to investigate unexpected conditions and implement contingency measures. Predictive modeling paired with monitoring can protect people and infrastructure while reducing the likelihood of major failures, delays, and added costs.

Keywords

real-time monitoring

construction risk

deep excavation

instrumentation

Atlanta projects

soldier-pile walls

tiebacks

ground movement

finite-element analysis

alarm thresholds