ON THE IMPORTANCE OF MONITORING TUNNELS FOR PROPER SEISMIC SAFETY ASSESSMENT AND RISK MANAGEMENT

  • 15 Jan 2024
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Monitoring tunnels for vibrations and deformations is not only critical during the construction phase but also their service life.

In 2012, the Tokyo-bound Sasago Tunnel suffered significant damage when nearly 150 concrete ceiling panels collapsed and crushed three vehicles, including a van carrying six people that caught fire. The deficiencies in mounting components of the ceiling panels were to blame.

But, are tunnels safe during an earthquake?

A common belief that underground structures are safer because they move with the soil, while structures above ground sway back and forth during the earthquakes appears to be misleading. The impact of earthquakes on tunnels can be severe due to ground failures such as liquefaction, strong ground shaking, and fault crossing.

Liquefaction takes place when saturated soft soil deposits loose load-carrying capacity during strong shaking. This phenomenon can cause the ground surrounding tunnels to deform and shift, with potentially severe impacts. The slope instability and fault crossings may also create permanent deformations leading to a collapse of the tunnel.

After the 1906 San Francisco earthquake, the Wrights railway tunnel in southern Santa Cruz mountains was closed for more than a year due to the collapse of approximately 100-m-long part crossing the San Andreas Fault Zone. Another railway tunnel crossing the White Wolf Fault was seriously damaged during the 1952 magnitude 7.5 Kern County earthquake associated with this fault (Kontogianni and Stiros, 2003).

In 1999 a magnitude 7.2 hit the Duzce region in Turkey. Close to the fault rupture, twin highway tunnels on the major highway connecting Ankara to Istanbul were under construction. The tunnels were partially collapsed due to intense pulses of earthquake motion (near-fault effects) as their lines cross the shear zone of the North Anatolian Fault.

The excavation process during tunnel construction may itself trigger microearthquakes. The vibrations, therefore need to be monitored to identify such seismic activity whether they create any movements or cracks on the tunnel surface. The monitoring vibrations is also needed to estimate the rock formations ahead of the tunnel face to optimize the excavation parameters. Besides, the infrastructure surrounding the tunnel including buildings must be monitored especially in case of construction of new subway (metro) lines.

Structural health monitoring (SHM) system is essential for the seismic resilience of tunnels. A robust real-time SHM system not only allows for assessment of accelerations and deformations (displacements and strains) in tunnel linings but also facilitates the implementation of adaptive risk management. Such a system can assist the officials to make informed and timely decisions to protect people (such as drivers or construction workers) from life-threatening conditions. For example, the highway tunnel can be closed to traffic before any severe consequences take place. Such pro-active actions would not only save lives but also avoid liabilities.

QuakeLogic is the only company providing cloud-based AI-powered disaster risk management solutions to prevent and reduce human and economic losses risen during and after earthquakes. Our cutting-edge technology platform performs real-time autonomous structural assessments using sensor data and sends rapid notifications after an event with the level of shaking intensity and whether structural integrity is compromised. For tunnels, our platform provides meaningful and easy-to-understand information immediately after an earthquake. This timely and critical information helps the officials to plan their emergency response. We also provide a web-based display where the sensor information can be monitored in real-time. This solution can provide great benefits especially for tunnels under construction phase.

For emergency measures and safety of tunnels, QuakeLogic provides advanced monitoring systems together with real-time and autonomous data analytics.

WHAT YOU NEED TO KNOW ABOUT PROPER MONITORING OF BRIDGES FOR EARLY DAMAGE DETECTION AND INTERVENTION

  • 15 Jan 2024
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There are about 56,000 structurally deficient bridges in the U.S., and these bridges accommodate on average 188 million trips each day according to data from the Federal Highway Administration.

The nation’s transportation infrastructure is aging. More than 200,000 bridges are now more than 50 years old, and many are approaching the end of their design life. Although the seismic construction requirements are aimed to protect the lives of those crossing bridges. The number of bridges that are in such poor condition as to be considered structurally deficient is increasing and posing potential risk.

Fourteen years ago, the Interstate 35 bridge over the Mississippi River in downtown Minneapolis collapsed. The cars, trucks and even a school bus were driving in bumper-to-bumper traffic across in the evening rush hour. Bridge’s failure plummeted them into the water and onto the rocky river banks. This disaster left a death toll of thirteen and injured 145. The officials were warned that the bridge was structurally deficient due to significant corrosion in its bearings. A federal inspection also rated the bridge structurally deficient, giving it a 50 on a scale of 100 for structural stability.

In 2018, another horrific bridge collapse occurred in the Florida International University campus in Miami. The failed pedestrian bridge killed six and injured eight people. The bridge was under construction and the errors in the design overestimated how much stress the structure could take.

The question arose about the cause of the collapse of bridges and whether they could have been prevented.

Emergent technologies in sensing, artificial intelligence (AI), and cloud computing are now remedying engineers to construct stronger bridges and also improve bridge maintenance for longer life-span. To provide continuous feedback on the bridge’s structural conditions, sensors supporting structural health monitoring (SHM) systems are being installed into both new and existing bridges.

A robust SHM system, including various sensors and data analytics to monitor the bridge’s real-time integrity, can provide officials and engineers with the knowledge and “peace of mind” that the bridge is performing as expected, and the ability to detect a change in its performance. This knowledge and ability are critical because they are directly responsible for the consequences of failure. To prevent catastrophic collapses, especially the bridges that require significant maintenance, rehabilitation, or replacement can significantly benefit from the SHM system to monitor its elements founds to be in poor condition due to deterioration or damage.

At QuakeLogic, we provide the most comprehensive SHM system for bridges. We are the only company with a cloud-based, AI-powered technology platform performing autonomous structural assessments using sensor data. Our platform sends rapid notifications with the level of shaking intensity in case of an earthquake and whether the bridge’s integrity is compromised. This system can not only monitor for earthquakes but also utilize data from various sensors such as accelerometers, potentiometers, inclinometers, strain gauges, thermocouples, and weather stations. Our platform sends meaningful and easy-to-understand information. This timely and critical information helps the bridge officials and engineers to give informed decisions and plan their responses appropriately.

Our structural health monitoring platform response matches for the first time the timing of the earthquake impact, which was impossible before. This platform can provide timely information that is needed for an understanding of the performance of a bridge and address problems earlier to improve public safety.

PROPER MONITORING CAN PROVIDE EARLY DAMAGE DETECTION AND INTERVENTION FOR DAMS

When disaster strikes, we are all at risk! The unprepared ones will get hit the hardest. Today, at least 1,680 dams across the U.S. rated in poor or unsatisfactory conditions. These dams pose potential risks according to the Associated Press article. Without urgent action, aging dams (dams in the U.S. are on average over 50 years old) may not be able to adequately handle the intense rainfall and floods of a changing climate or imminent earthquakes. Because the housing developments are often located nearby these dams, they may fail to protect people.

The significance of structural health monitoring (SHM) for dam safety is widely acknowledged. There are a number of unfortunate examples of failed dams where early signs of deficiencies might have been monitored and detected if a proper SHM system had been in place. A robust SHM system can provide timely information that is needed for an understanding of the performance of a dam. The SHM system, including instrumentation and data analytics, can provide dam owners with the knowledge that a dam is performing as expected, and the ability to detect a change in its integrity. This knowledge and ability are critical for the dam owners because they are directly responsible for the consequences of failure. Because of these reasons, a robust safety monitoring system should be a fundamental part of every dam owners risk management progra

QuakeLogic provides the most comprehensive structural health monitoring solution for dams. We are the only company with a cloud-based, AI-powered technology platform performing autonomous structural assessments using sensor data. After an earthquake occurs, our platform sends rapid notifications to our users. These notifications include the level of shaking intensity and whether the structural integrity of the dam is compromised. This system not only monitors earthquakes but also utilizes data from various sensors such as potentiometers, strain gauges, thermocouples, weather stations, piezometers and seepage (weirs & flumes).

QuakeLogic’s intelligent structural health monitoring platform generates meaningful and easy-to-understand information. This timely and critical information helps the dam owners to give informed decisions and plan their responses appropriately.

We provide “peace of mind” to dam owners. To learn about our risk management solutions, please contact us at info@quakelogic.net