Re-evaluation of the Design during Construction with Monitoring Data and Utilization of the Observational Method in Shoring Works-Paper

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The paper examines how monitoring data can support design reassessment during excavation and enable the observational method in shoring projects. Inclinometers, reflectometers, and anchor load cells were used to compare actual performance with design predictions in two Istanbul case studies.<br /><br />In the first project, a 13.3 m-deep excavation was supported by a diaphragm wall and prestressed anchors. Measured wall movements were substantially lower than predicted. Back-analysis indicated that the final anchor row could be omitted while maintaining displacement limits. The revised design reduced the budget by 3%, completion time by 20%, and CO₂ emissions by 5%.<br /><br />In the second project, a 23 m-deep excavation initially used soil nails. Monitoring showed movements exceeding predictions, triggering additional support measures: anchors and piles were introduced, and the remaining excavation used a mixed system. Compared with using anchored bored piles throughout, the revised approach reduced costs by about 8% and completion time by 20%, while estimated CO₂ emissions remained similar.<br /><br />The cases demonstrate that monitoring can identify both overdesign and insufficient support, allowing timely adjustments to maintain safety and improve project efficiency. The authors recommend planning the observational method from the design stage, with defined performance limits and contingency measures. This approach can help reduce costs, construction duration, and environmental impacts when ground behavior is uncertain.

Keywords

monitoring data

design reassessment

observational method

shoring projects

excavation support

inclinometers

anchor load cells

back-analysis

cost reduction

CO2 emissions