Embodied Energy: Soil Retaining Geosystems

Kenichi Soga,Chris Chau,Duncan Nicholson,Heleni Pantelidou 대한토목학회 2011 KSCE JOURNAL OF CIVIL ENGINEERING Vol.15 No.4

Embodied energy is defined as the total energy in joules that can be attributed to bringing an item to its existing state. This paper attempts to quantify the amount of energy that is put into constructing geotechnical structures. In this study, several common retaining wall options are designed for (i) a hypothetical highway widening project based on a typical condition in London, (ii)basement construction of actual high rise buildings in London and (iii) embankments and cuttings as part of an actual highway road widening project. The embodied energy of each design was computed. Results show that the largest variance on embodied energy is the design solutions and within a given design the materials energy dominates over the installation energy and the transportation energy. The choice of Embodied Energy Intensity (EEI) of materials, particularly steel and concrete, is shown to have a large influence on the magnitude of embodied energy. When comparing among different designs of soil retaining structures, a recycled steel wall system generally has less embodied energy than the equivalent concrete wall system, which is more efficient than the equivalent virgin steel system. Results of the three case studies collectively indicate that minimizing materials usage is the key for reducing embodied energy in soil retention projects.

Performance monitoring of timber structures in underground construction using wireless SmartPlank

Xu, Xiaomin,Soga, Kenichi,Nawaz, Sarfraz,Moss, Neil,Bowers, Keith,Gajia, Mohammed Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Although timber structures have been extensively used in underground temporary supporting system, their actual performance is poorly understood, resulting in potentially conservative and over-engineered design. In this paper, a novel wireless sensor technology, SmartPlank, is introduced to monitor the field performance of timber structures during underground construction. It consists of a wooden beam equipped with a streamlined wireless sensor node, two thin foil strain gauges and two temperature sensors, which enables to measure the strain and temperature at two sides of the beam, and to transmit this information in real-time over an IPv6 (6LowPan) multi-hop wireless mesh network and Internet. Four SmartPlanks were deployed at the London Underground's Tottenham Court Road (TCR) station redevelopment site during the Stair 14 excavation, together with seven relay nodes and a gateway. The monitoring started from August 2013, and will last for one and a half years until the Central Line possession in 2015. This paper reports both the short-term and long-term performances of the monitored timber structures. The grouting effect on the short-term performance of timber structures is highlighted; the grout injection process creates a large downward pressure on the top surface of the SmartPlank. The short and long term earth pressures applied to the monitored structures are estimated from the measured strains, and the estimated values are compared to the design loads.

Performance monitoring of timber structures in underground construction using wireless SmartPlank

Xiaomin Xu,Kenichi Soga,Sarfraz Nawaz,Neil Moss,Keith Bowers,Mohammed Gajia 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Although timber structures have been extensively used in underground temporary supportingsystem, their actual performance is poorly understood, resulting in potentially conservative andover-engineered design. In this paper, a novel wireless sensor technology, SmartPlank, is introduced tomonitor the field performance of timber structures during underground construction. It consists of a woodenbeam equipped with a streamlined wireless sensor node, two thin foil strain gauges and two temperaturesensors, which enables to measure the strain and temperature at two sides of the beam, and to transmit thisinformation in real-time over an IPv6 (6LowPan) multi-hop wireless mesh network and Internet. FourSmartPlanks were deployed at the London Underground’s Tottenham Court Road (TCR) stationredevelopment site during the Stair 14 excavation, together with seven relay nodes and a gateway. Themonitoring started from August 2013, and will last for one and a half years until the Central Line possessionin 2015. This paper reports both the short-term and long-term performances of the monitored timberstructures. The grouting effect on the short-term performance of timber structures is highlighted; the groutinjection process creates a large downward pressure on the top surface of the SmartPlank. The short and longterm earth pressures applied to the monitored structures are estimated from the measured strains, and theestimated values are compared to the design loads.

Wireless sensor networks for underground railway applications: case studies in Prague and London

Peter J. Bennett,Kenichi Soga,Ian Wassell,Paul Fidler,Keita Abe,Yusuke Kobayashi,Martin Vanicek 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.6

There is increasing interest in using structural monitoring as a cost effective way of managing risks once an area of concern has been identified. However, it is challenging to deploy an effective, reliable, large-scale, long-term and real-time monitoring system in an underground railway environment (subway / metro). The use of wireless sensor technology allows for rapid deployment of a monitoring scheme and thus has significant potential benefits as the time available for access is often severely limited. This paper identifies the critical factors that should be considered in the design of a wireless sensor network, including the availability of electrical power and communications networks. Various issues facing underground deployment of wireless sensor networks will also be discussed, in particular for two field case studies involving networks deployed for structural monitoring in the Prague Metro and the London Underground. The paper describes the network design, the radio propagation, the network topology as well as the practical issues involved in deploying a wireless sensor network in these two tunnels.

Wireless sensor networks for underground railway applications: case studies in Prague and London

Bennett, Peter J.,Soga, Kenichi,Wassell, Ian,Fidler, Paul,Abe, Keita,Kobayashi, Yusuke,Vanicek, Martin Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.5

There is increasing interest in using structural monitoring as a cost effective way of managing risks once an area of concern has been identified. However, it is challenging to deploy an effective, reliable, large-scale, long-term and real-time monitoring system in an underground railway environment (subway / metro). The use of wireless sensor technology allows for rapid deployment of a monitoring scheme and thus has significant potential benefits as the time available for access is often severely limited. This paper identifies the critical factors that should be considered in the design of a wireless sensor network, including the availability of electrical power and communications networks. Various issues facing underground deployment of wireless sensor networks will also be discussed, in particular for two field case studies involving networks deployed for structural monitoring in the Prague Metro and the London Underground. The paper describes the network design, the radio propagation, the network topology as well as the practical issues involved in deploying a wireless sensor network in these two tunnels.

Fabrication and packaging techniques for the application of MEMS strain sensors to wireless crack monitoring in ageing civil infrastructures

Matteo Ferri,Fulvio Mancarella,Ashwin Seshia,James Ransley,Kenichi Soga,Jan Zalesky,Alberto Roncaglia 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.3

We report on the development of a new technology for the fabrication of Micro-Electro-Mechanical-System (MEMS) strain sensors to realize a novel type of crackmeter for health monitoring of ageing civil infrastructures. The fabrication of micromachined silicon MEMS sensors based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry is presented, using a novel process which includes a gap narrowing procedure suitable to fabricate sensors with low motional resistance. In order to employ these sensors for crack monitoring, techniques suited for bonding the MEMS sensors on a steel surface ensuring good strain transfer from steel to silicon and a packaging technique for the bonded sensors are proposed, conceived for realizing a low-power crackmeter for ageing infrastructure monitoring. Moreover, the design of a possible crackmeter geometry suited for detection of crack contraction and expansion with a resolution of 10 and very low power consumption requirements (potentially suitable for wireless operation) is presented. In these sensors, the small crackmeter range for the first field use is related to long-term observation on existing cracks in underground tunnel test sections.

Fabrication and packaging techniques for the application of MEMS strain sensors to wireless crack monitoring in ageing civil infrastructures

Ferri, Matteo,Mancarella, Fulvio,Seshia, Ashwin,Ransley, James,Soga, Kenichi,Zalesky, Jan,Roncaglia, Alberto Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.3

We report on the development of a new technology for the fabrication of Micro-Electro-Mechanical-System (MEMS) strain sensors to realize a novel type of crackmeter for health monitoring of ageing civil infrastructures. The fabrication of micromachined silicon MEMS sensors based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry is presented, using a novel process which includes a gap narrowing procedure suitable to fabricate sensors with low motional resistance. In order to employ these sensors for crack monitoring, techniques suited for bonding the MEMS sensors on a steel surface ensuring good strain transfer from steel to silicon and a packaging technique for the bonded sensors are proposed, conceived for realizing a low-power crackmeter for ageing infrastructure monitoring. Moreover, the design of a possible crackmeter geometry suited for detection of crack contraction and expansion with a resolution of $10{\mu}m$ and very low power consumption requirements (potentially suitable for wireless operation) is presented. In these sensors, the small crackmeter range for the first field use is related to long-term observation on existing cracks in underground tunnel test sections.

Wireless operational modal analysis of a multi-span prestressed concrete bridge for structural identification

Matthew J. Whelan,Michael V. Gangone,Kerop D. Janoyan,Neil A. Hoult,Campbell R. Middleton,Kenichi Soga 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.5

Low-power radio frequency (RF) chip transceiver technology and the associated structural health monitoring platforms have matured recently to enable high-rate, lossless transmission of measurement data across large-scale sensor networks. The intrinsic value of these advanced capabilities is the allowance for high-quality, rapid operational modal analysis of in-service structures using distributed accelerometers to experimentally characterize the dynamic response. From the analysis afforded through these dynamic data sets, structural identification techniques can then be utilized to develop a well calibrated finite element (FE) model of the structure for baseline development, extended analytical structural evaluation, and load response assessment. This paper presents a case study in which operational modal analysis is performed on a three-span prestressed reinforced concrete bridge using a wireless sensor network. The low-power wireless platform deployed supported a high-rate, lossless transmission protocol enabling real-time remote acquisition of the vibration response as recorded by twenty-nine accelerometers at a 256 Sps sampling rate. Several instrumentation layouts were utilized to assess the global multi-span response using a stationary sensor array as well as the spatially refined response of a single span using roving sensors and reference-based techniques. Subsequent structural identification using FE modeling and iterative updating through comparison with the experimental analysis is then documented to demonstrate the inherent value in dynamic response measurement across structural systems using high-rate wireless sensor networks.

Wireless operational modal analysis of a multi-span prestressed concrete bridge for structural identification

Whelan, Matthew J.,Gangone, Michael V.,Janoyan, Kerop D.,Hoult, Neil A.,Middleton, Campbell R.,Soga, Kenichi Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.5

Low-power radio frequency (RF) chip transceiver technology and the associated structural health monitoring platforms have matured recently to enable high-rate, lossless transmission of measurement data across large-scale sensor networks. The intrinsic value of these advanced capabilities is the allowance for high-quality, rapid operational modal analysis of in-service structures using distributed accelerometers to experimentally characterize the dynamic response. From the analysis afforded through these dynamic data sets, structural identification techniques can then be utilized to develop a well calibrated finite element (FE) model of the structure for baseline development, extended analytical structural evaluation, and load response assessment. This paper presents a case study in which operational modal analysis is performed on a three-span prestressed reinforced concrete bridge using a wireless sensor network. The low-power wireless platform deployed supported a high-rate, lossless transmission protocol enabling real-time remote acquisition of the vibration response as recorded by twenty-nine accelerometers at a 256 Sps sampling rate. Several instrumentation layouts were utilized to assess the global multi-span response using a stationary sensor array as well as the spatially refined response of a single span using roving sensors and reference-based techniques. Subsequent structural identification using FE modeling and iterative updating through comparison with the experimental analysis is then documented to demonstrate the inherent value in dynamic response measurement across structural systems using high-rate wireless sensor networks.