Tunnel Business Magazine

APR 2018

TBM: Tunnel Business Magazine is the market leader for North America. TBM is written for leading professionals in all aspects of tunneling and covers project stories, design elements, contracting strategies, legal issues, new technology and more.

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Page 38 of 47

TUNNELINGONLINE.COM F E A T U R E S T O RY 3 9 TBM: TUNNEL BUSINESS MAGAZINE // APRIL 2018 wireless network covering the manufacturing facility, the stor- age areas and the transport system into the tunnel. The system also offers instant feedback to the workforce operator on site to ensure that the process is proceeding as planned. The bar codes and RFID tags are cross-referenced across the SDS.Production and SDS.Storage modules that form the basis of the SDS system database so that, for example, at the first stage of manufacture the barcode of the segment mold and barcode on the reinforc- ing cage can be registered in the system. The design process then checks and matches that the correct reinforcing system is being used with the correct mold for the planned segment. If the reinforcing cage does not match with that required within the database this information can be transmitted back to the production floor and the necessary changes made to ensure that there is no waste of time or materials by production of an incorrect segment. THE SDS SEGMENT LIFE-CYCLE AT SANTA LUCIA The production of liner segments for a tunnel operation such as Santa Lucia starts well in advance of the day any one seg- ment is required at the face. This is because all segments have to undergo a 28-day full cure cycle to ensure they attain the correct concrete strength prior to installation. So, what is the life cycle following one segment through the SDS system? The first step of producing a segment is to assemble the rein- forcement cage. This has added to it a barcode and in the case of the Santa Lucia process, an RFID tag. The cage is then paired with the required segment mold in the segment production hall. The barcode for the mold – each mold has an individual barcode – is matched with the barcode of the reinforcement to ensure that the correct pairing is achieved prior to production of the segment. The mold is then prepared for concreting and the carousel operator initiates the next cycle. Before entering the concreting chamber, SDS identifies the mold by reading an RFID tag that is mounted on every mold. Using an interface to the concrete batching plant, the system automatically orders a concrete batch according to the segment type to be produced in this mold. During the casting process, the batch information and raw materials will be transferred to the database and directly into the segment quality documentation. Once this process is completed and the information passed to the SDS system to mark the time of concreting, the mold then passes into a heated curing tunnel. The mold stays in the heat- ed tunnel to facilitate the initial cure of the concrete for about 5 hours. After exiting the tunnel the SDS system monitors the curing duration to ensure the correct time has been achieved. The segment can then be removed from the mold and given its own unique barcode for future processing and the segment is added into the SDS system. The segment is then checked for damage or malformation before being cleared through the SDS system for transport to storage. Prior to transportation to the storage facility, a second scanner is used to check that the RFID tag, now located within the concrete of the segment, is still in working order. While not used as part of the production pro- cess, management and monitoring its future use means that each segment has to have a working RFID tag before installa- tion into the tunnel. The completed segment is then transported to the storage fa- cility where the barcode is again checked and the segment's po- sition in the store area is marked and logged on the SDS system. Once the 28-day cure is completed and the segment is avail- able to be called to site with its other liner ring partners, the SDS scanner is again used to indicate which segments are leav- ing the storage site and to generate a delivery note. The seg- ments are loaded onto a delivery truck and transported to the e delivere f the delivery and this information is returned to the SDS system for closure of the system relating to that particular segment and the others that have been on the same delivery. While not part of the Santa Lucia Tunnel arrangement, the SDS system also has facility if required on other sites to mea- sure and store geometric data for segments once out of the mold to ensure quality and compliance with requirements. The manufacture and storage systems also ensure that the correct rings are transported to the construction face in the correct order for installation so as to again minimize the po- tential for delays at the face as materials do not have to be re- ordered on arrival at their point of installation. The system also enables the transport team to ensure that should anything happen during the movement of the segments, such as damage while craning, this can be logged and dealt with at the earliest opportunity. In the case of the Santa Lucia Tunnel, the requirement for the use of RFID tags was something requested by the client as the project was being designed. While not a vital component for the main construction and segment manufacture and handling process of the tunnel, it does ensure that at any time in the future (the tunnel has a minimum design life of around 100 to 150 years) each and every individual segment can be traced and accounted for from the construction database, particularly helpful for maintenance works or should damage occur due to unforeseen circumstances. For example, should it be discovered that a selection of segments were made us- ing an incorrect concrete mix with one having shown signs of failure, then all segments affected by this can be found and tested individually by use of the RFID tag to identify their positions in the tunnel from the records and using an RFID scanner to locate them on site. Commenting on the use of the SDS system with RFID tags for the Santa Lucia Tunnel project Florian Werr manager for the SDS system, said: "The implementation of the SDS system on tunneling projects such as this offers much more than simple segment management. Our system enables the workforce across the site to know that the segments have been manufactured to the highest quality, handled with the utmost care and delivered at the right time and to the right place. This is all achieved with the wireless interface and feedback pro- cess that means the SDS system is as much an active part of the tunneling process as the excavation of the gr Furthermore, with a beast of machine like the Herrenknecht t is boring the Santa Lucia Tunnel if it is not fed correctly it will simply stop working – and that is something that no-one on site wishes to see!"

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