Performance Monitoring for Deep Excavations

"This presentation will showcase two challenging projects with deep excavation support systems in the Atlanta area where state-of-the-art instrumentation and monitoring systems were used to manage risk by confirming design performance requirements / calculations during construction. The instrumentation and monitoring system successfully reduced risk by recording real-time data on a project website while simultaneously sending email alarms to key site personnel when data exceeded pre-determined alarm thresholds. The monitoring data revealed unexpected performance at an early enough stage so that contingency plans could be engaged and remedial efforts devised in order to limit the consequences. Finite element analysis was used to model deformations, analyze the unexpected performance, and prepare theremedial design.INTRODUCTIONConstruction in densely populated urban areas is becoming more common in order to keep up with the increasing infrastructure demands of our growing population. America’s big cities continue to outpace the overall nation in population growth. The city of Atlanta, the nation’s ninth largest city based on metropolitan population, is a prime example of this. The population has grown at a rate of 6.6% between 2010 and 2013, nearly triple the overall growth rate of the United States during the same period (SustainAtlanta, 2015).As a result of increasing infrastructure demands in Atlanta, developers are now constructing larger buildings on smaller properties. In addition, developers are attempting to maximize space on their selected properties, often by designing underground parking garages to accommodate as many cars as possible on these compact sites. In some cases the selected sites are adjacent to buildings, utilities, and other existing structures. The risk associated with construction increases during underground work that requires a support of excavation system, particularly on confined sites adjacent to existing structures. There is a risk posed to people, property, and the environment that the project team should monitor when constructing in these conditions."