DISTRIBUTED FIBER OPTIC MONITORING OF A HIGH-RISE BUILDING PILE-RAFT FOUNDATION: COMMISSIONING CONTROL AND BASELINE ASSESSMENT

Abstract

The structural monitoring of high-rise building foundations requires measurement systems that can register spatially distributed deformation and temperature effects during construction and at the early stage of service. This paper presents a field case study of a distributed fiber optic sensing (DFOS) system installed in the raft foundation of a high-rise building complex. The study is focused not on general crack detection, but on the practical commissioning of the sensing line, interpretation of initial measurements, and preparation of a reference dataset for subsequent long-term observation.

The monitoring object is the raft foundation beneath Block R of Abu Dhabi Plaza in Astana, Kazakhstan. Measurements were obtained along the same horizontal sensing route using Brillouin Optical Time Domain Analysis (BOTDA). Two commissioning stages were compared in order to evaluate the repeatability of the installed system and to separate temporary construction-stage influences from the stable response of the foundation slab.

The analysis showed that signal variability during the first measurement stage was mainly associated with ongoing construction operations, including concrete casting and related thermal-mechanical disturbances. In the second stage, after the completion of active works on the monitored section, the measured strain and temperature responses became significantly more stable. This state can be used as an engineering baseline for future inspections of the foundation.

The proposed approach demonstrates how DFOS data can be converted from raw distributed measurements into a practical monitoring basis for reinforced concrete substructures. The results are relevant for commissioning control, baseline formation, diagnostic comparison of future measurements, and further integration of monitoring results into BIM-based or digital twin workflows.