How ground vibration monitoring has changed over the past fifty years
How ground vibration monitoring has changed over the past fifty years
Looking back in time to as recently as the 1960s, the technology to measure ground-borne vibration from civil engineering and quarrying activities didn’t exist. Back then there were just a few mechanical units available but they were very expensive and uncommon. They used a heavy cast iron weight suspended between leaf springs. Ground movement would cause the weight to move and translate the movement through levers to a metal stylus that pressed against a clear acetate ribbon powered by a clockwork mechanism. In use, the stylus etched into the acetate ribbon as it was powered through the machine and recorded the ground vibration. To read the results, the acetate ribbon was removed and had carbon black rubbed into the scored trace. The ribbon was then viewed over a light box and the trace was measured against a nomogram to give results in terms of Peak Particle Velocity (PPV) in inches per second in the chosen axis. The cast iron weight could be used in either a vertical or a horizontal position.
In the late 1970s electronic ground vibration recorders began to appear. The circuitry was based on transistor, transistor logic (TTL) and they were unable to save measured results as they had no memory facility. A built in printer was used to show the measured data. They were very expensive and powered by lead acid batteries, so they were very big and heavy.
Just over a decade later in the late 1990s, ground vibration meters used microprocessor technology, so recorded data could be stored in memory and later downloaded to a computer. The data was post processed using proprietary software supplied by the seismograph manufacturer. Results could then be viewed, printed in report format or archived. However, problems were often encountered when trying to connect a seismograph to a computer with compatibility issues with leads, plugs, sockets and correct configuration of computer ports. Other problems could also arise when installing and running manufacturer’s software. So in order to go out and measure ground vibration a user had to be competent and experienced in setting up and using the monitor, installing and configuring the software, connecting the instrument to a computer and then using the program to create a report. Using a ground vibration monitor was time consuming and often frustrating and little changed for twenty years.
And so it was until the second decade of the 21st century. Now there are seismographs that are able to automatically send data via WiFi to the Internet with the results stored in ‘the Cloud’ for instant access almost anywhere in the world.
The latest generation of ground vibration monitors may be delivered to the site pre-configured meaning that the user has only to unpack the box and press the on button to start monitoring. The benefits to the user of these latest systems are that no set-up is necessary, no software installation is needed on the user’s laptop is required and no manual is needed, with the results able to be viewed anywhere via the Cloud. Alerts may also be assigned to let users know via their cell phone when threshold levels are exceeded.
Another significant improvement is that these latest ground vibration monitors use circuitry with very low current consumption meaning that battery life has hugely improved to allow up to three months of unattended monitoring from a single charge.
From an on-site user’s point of view, these latest ground vibration monitors remove all the compatibility worries and time consuming issues that were often met using the older equipment. Now virtually anyone is able to unbox the kit and have it switched on and working and relaying data to the Cloud within a few minutes.
WiFi enabled ground vibration monitors are ideal for remote monitoring when measuring in compliance with planning conditions, or to record background levels.
In areas without a WiFi connection, alternative ground vibration monitors must be chosen. An ideal instrument is the Accudata GVM-10 seismograph. It is one of the most accurate ground vibration meters available and will measure in full compliance with BS 5228-2:2009+A1:2014. The Accudata GVM-10 is very capable and easy to use and stores event data on a removable SD card. The SD card is then plugged into a laptop and the data appears in a dialogue box for archiving or viewing using the supplied software application.
Accudata offer a full range of Seismographs for sale and ground vibration monitors for hire
