Ground Vibration Monitoring during dynamic works
Dynamic Compaction, Rapid Impact Compaction, impact rolling, vibro techniques and driven piling transmit vibration through the ground. Ground vibration monitoring measures it at the structures, services and slopes that could be affected, using triaxial seismographs that record peak particle velocity and frequency. Readings are compared with alert, action and stop levels agreed with the consultant, so the work can continue safely, be adjusted by reducing energy or increasing distance, or be stopped before damage occurs.
When the test is used
Typically used for…
- Dynamic Compaction, Rapid Impact Compaction and impact rolling near structures.
- Vibro compaction, vibro replacement and driven piling.
- Sensitive buildings, retaining walls, pipelines and services.
- Establishing safe working distances in a trial.
Limitations
- Limits depend on the structure type and condition and the vibration frequency.
- Readings are point measurements; enough monitors must be placed where the risk is highest.
- Background vibration from traffic and plant must be distinguished.
- A pre-condition survey is needed to separate existing damage from new.
The test type, number and locations are agreed with the consultant for each project.
How the test works
A pre-condition survey records the state of nearby structures. Triaxial seismographs are fixed to the ground or structure at the agreed locations and set to record peak particle velocity and frequency in three directions.
During the work, readings are reviewed against the alert, action and stop levels. In a trial, readings at different distances build an attenuation relationship that sets safe working distances and energy for production.
Test planning inputs
- Structures, services and slopes within the zone of influence.
- Vibration limits and alert, action and stop levels.
- Work method, energy and distance.
- Monitoring locations and recording settings.
- Reporting frequency and response actions.
Calibration and equipment checks
- Pre-condition survey of nearby structures.
- Instrument calibration and installation checks.
- Trial at increasing distance or energy to set safe working distances.
Test execution controls
- Monitors fixed, levelled and recording at the agreed settings.
- Readings reviewed against trigger levels during each shift.
- Exceedances reported and the agreed response action taken.
- Instrument battery, memory and calibration checked.
Interpretation and reporting
The test plan, the raw record and the interpretation are kept separate, so it is always clear what was specified, what was measured and what it shows.
What is specified
Vibration limits and trigger levels agreed with the consultant.
What was measured
Continuous records of peak particle velocity and frequency at each monitor.
What it shows
Monitoring reports with exceedances and actions, and a post-condition survey where required.
Deliverables
- Monitoring plan
- Pre-condition survey
- Calibration certificates
- Vibration records
- Daily or weekly monitoring reports
- Attenuation analysis
Discuss the testing your project needs.
Share the project stage, the ground conditions and the specification or acceptance criteria.