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Seismic vibration monitoring

Posted May 5, 2018

The best solution for seismic vibration monitoring from earthworks around sensitive locations

Seismic vibration can refer to different types of movement travelling through the earth. It can occur due to natural (earthquake) or artificial (earthworks or drilling) causes.

Changing the lie of the land is disruptive and, as a result, earthworks causes seismic vibration that requires monitoring and control.

Compaction works carried out as part of Melbourne’s $2.25 billion M80 Ring Road Upgrade roadworks caused tremor concerns at sensitive locations on the southern side of the arterial near Sydney Road.

Contractors utilised ground vibration equipment to measure limits while the roadworks continued. However, such solutions are time consuming and expensive because they require a consultant to be onsite permanently.

Unfortunately, standards in Australia for seismic vibration monitoring are somewhat vague. Currently, no Australian Standard for assessment of building damage caused by vibrational energy exists. The most relevant standards come from the United Kingdom, the United States and Germany.

The levels specified are peak component particle velocities. Frequency-independent and frequency-dependent guide levels are described in:

  • British Standard BS 7385–2: 1993 Evaluation and measurement for vibration in buildings. Guide to damage levels from ground-borne vibration
  • United States Bureau of Mines (USBM) RI 8507 Impacts to structures.

The British and US standards both use similar methods for assessing frequencies. The recommended approach to assessing blast-induced vibration effects on buildings is the frequency-dependent criteria.

According to the Federal Government’s Department of Industry, Innovation and Science, the guide values and assessment methods provided in BS 7385–2 and (USBM) RI 8507 are applicable to Australian conditions.

The more conservative German Standard – DIN 4150–3:1999–02 Vibration in buildings—Part 3: effects on structures – provides recommended maximum levels of vibration that reduce the likelihood of building damage.

These levels are ‘safe limits’, up to which no damage due to tremors has been observed. ‘Damage’ can include even minor issues such as superficial cracking in cement render, the enlargement of existing cracks, and the separation of partitions from load-bearing walls.

 

The impact of seismic vibrations

In moderate cases, exceeding vibration limits may affect or damage machinery calibrations. In more extreme cases, shaking can cause cracking and alter the structural integrity of buildings.

Seismic vibration can even cause catastrophic failure as occurred following the earthquakes that hit Christchurch on New Zealand’s South Island during 2010 and 2011.

The first in September 2010 was more powerful at a magnitude 7.1 but it was the second (magnitude of 6.3) in February 2011 that caused the most damage. This earthquake occurred on a shallow fault line close to the CBD so the shaking was particularly destructive.

Two major buildings collapsed while heritage buildings including two cathedrals suffered significant damage. More than half of the CBD’s buildings were demolished, including the city’s tallest building.

Deloitte has calculated the total cost of the quakes to be more than $10 billion.

 

Automated seismic vibration monitoring

Continuous seismic vibration monitoring is crucial to the success of large-scale construction projects.

The Industrial Internet of Things (IotT) provides automated solutions such as the AlphaX CT, which will save project managers both time and money.

The AlphaX CT is solar powered so it doesn’t require connection to electricity or the constant charging of batteries.

The device is IP67 rated so it’s able to be left onsite out in the rain or other adverse weather conditions and will continue to operate effectively.

Simply turn on the device and it will start monitoring seismic vibration.

You will be alerted when limits are exceeded so you don’t have keep checking in on the unit.

Talk to M innovation today about an IoT solution for your project.