INOVAINFRA 2024

Lucio Souza (1), Carlos Peña (1), Ivo Teixeira (1), Andrea Scremin (1), Roberto Collado (2), David Mendi (2)

(1) ACCIONA Construcción, São Paulo, Brazil
(2) Geprode Consultores LTDA, São Paulo, Brazil

The alignment of the future São Paulo Metro Line 6 – Orange Line (Brazil) runs, among other areas, through the neighborhoods of Pompeia and Perdizes (Fig. 1), by means of a mechanized tunnel excavation using a shield TBM. These districts are characterized by a high density of high-rise buildings, many exceeding 10 storeys (Fig. 2). Therefore, the need to prevent geological risks related to differential settlements and the resulting angular distortions is critical to ensure that construction is carried out under appropriate safety conditions.

The initial project design предусматриes geotechnical monitoring using manual control instruments with a frequency of two readings per day. ACCIONA determined that it was necessary to increase the monitoring frequency so that, in the event of the activation of a pathology, incident, or settlement behavior differing from that estimated in the design, the time interval between onset, detection, and communication to responsible personnel could be reduced, enabling the timely adoption of preventive and/or corrective measures.

Fig. 1 – TBM section between the Secs–Pompeia (SEP), Perdizes (PDZ), and PUC Cardoso (PUC) stations, showing the 12 buildings equipped with automated instrumentation.

 

 

Fig. 2 – High density of buildings with more than 10 storeys between the Perdizes and PUC stations.

 

After studying different options to implement continuous 24/7 monitoring, as required for each involved building, their economic infeasibility was confirmed. The cost of any of these automated options represented an additional expense between 100% and 150% higher than the manual design option.

 

In view of this situation, ACCIONA drew on its experience from a similar scenario during the construction of the first line of the Quito Metro in Ecuador. In that case, due to the historical value of the city’s historic center—a UNESCO World Heritage Site—a process was developed, following a thorough selection of buildings and TBM passage times, for the installation, dismantling, and relocation of relocatable automated topographic monitoring systems, providing continuous 24/7 control during TBM advancement.

 

On Line 6, the selected technological solution consisted of automated inclinometers from the brand SENCEIVE® (www.senceive.com), due to their ease of installation and removal, autonomous communication and data transmission capabilities, and the independence of each building’s instrumentation from the others. Each system consists of one automated triaxial inclinometer (Fig. 3) installed at each instrumented point, equipped with battery power and Wi-Fi connectivity, and a gateway (Fig. 4) that receives the readings collected from all instrumented points via Wi-Fi and transmits them over the Internet to a web platform (Fig. 5). This platform stores the data, generates graphs, and issues alert notifications (via e-mail and SMS) whenever predefined threshold levels are exceeded.

Fig. 3 – SENCEIVE® automated triaxial inclinometer.

 

 

Fig. 4.- Gateway SENCEIVE®

 

Fig. 5 – Example of the WEBMONITOR® website.

The structural systems of the buildings were analyzed, and the most representative points were selected to monitor potential angular distortions and inclinations that could compromise their structural integrity. The operating period of the automated instrumentation on each building depended on the duration of the TBM passage within its zone of potential influence, averaging five days. To this period, additional time for installation, testing, and removal was added, resulting in an average total duration of 28 days.

Using two independent systems—each consisting of one gateway and six automated inclinometers—it was possible to continuously monitor the 12 selected buildings along the section between the SESC Pompeia, Perdizes, and PUC stations on a 24/7 basis. These systems are currently available for deployment on other buildings as the TBM advances.

In addition to a significant increase in safety levels, the use of this relocatable instrumentation solution (Figs. 1 and 6) resulted in a cost saving of 66% compared to the manual monitoring option.

Fig. 6 – Sequence of TBM advancement (from A to H) and relocation of automated instruments on the buildings.

 

Keywords: instrumentation, monitoring, settlement, automation, innovation.