Demolition holds back the tremors

London construction company uses ground vibration sensors to monitor vibrations during demolition work.


nstruments for monitoring ground vibration levels have been used on a sensitive construction project in London. AcSoft Sound & Vibration supplied two of the Menhir (Modular Enhanced Intelligent Recorder)

monitoring instruments from Semex Engcon to Pace Consult for use on a Rydon Construction project at The Broadway in Ealing. The project included demolition work on residential properties and derelict warehouses in the district. Pace Consult provides services to the construction

industry relating to acoustics and vibration and was helping Rydon Construction to achieve the necessary compliance within the project timescale. The simple, flexible and robust Menhir ground

vibration monitor efficiently measures vibrations, shocks and tremors generated by construction and building works as well as mining, demolition and quarrying activities. Joan-Carles Blanco, Associate Director at Pace Consult comments: “We have been working with AcSoft’s sister business Svantek for five years and used its noise and vibration instrumentation very successfully across a wide range of projects during that time.” When asked to provide ground vibration monitoring to satisfy both resident and local authority requirements during major demolition works, Svantek referred Pace Consult to AcSoft and its web-based, high resolution Menhir system. “When used in conjunction with smart data centre software, the Menhir is capable of accurately recording, analysing and transferring data from complex vibration monitoring applications in harsh environments,” says Blanco. The two AcSoft Menhir systems were installed at

an adjacent property within the residential corridor of the construction site and inside the derelict warehouse being demolished where they provided continuous ground vibration monitoring for five months.

❱ ❱ The Menhir vibration monitoring instrument provides intuitive customisation at construction sites to enable easy monitoring and compliance


An optional complete analysis module is also available, allowing reports to be automatically generated and transmitted electronically in freely adjustable intervals. It incorporates a selectable alarm output to designated personnel using SMS or email. According to Blanco, the smart data centre

software offers a fully integrated cloud based approach which proved to be invaluable when power to the Menhir devices on the demolition site was cut for a period of time. “It enabled us to still get quick access to data and device status at any time from a PC, tablet or smartphone,” he says. At one point, the Menhirs detected increased ground vibration when heavy plant machinery was being used and immediately sent an alarm to the site manager via SMS.

INTUITIVE CUSTOMISATION Allowing easy operation with minimal training, the intuitive Menhir can be customised to suit individual monitoring requirements and configured for immediate set up and use. A simple configuration tool means settings can be changed at any time, with quick and full access to the monitor’s parameters and values, as well as all analytical options and results. For maximum flexibility, the Menhir is available with internal and external SIM card slots. The latter enables the user to determine which provider is transmitting data, without having to open the device. The system can also be equipped with a low cost M2M system. An internal battery provides up to 48 hours

operating autonomy, depending on transmission requirements. The Menhir can be placed with up to 15° offset on the ground. The measurement device detects the offset and corrects it automatically. It can also be aligned with the three integrated levelling screws so no mounting platform is required. The Menhir offers a dynamic range > 130dB at 100 measurements per second per channel, as well as a bandwidth from 1 to 400 Hz.

Climatic & Vibration Testing Vol 2 No. 1 /// 13

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