Vibration Monitoring is performed by documenting ground borne vibrations during construction by a monitoring consultant such as Big Apple. This type of monitoring helps protects the adjacent structure from exceeding the pre-determined vibration limitations and assists the contractor with mitigating their activity to reduce vibrations. Big Apple offers two forms of monitoring:
Remote Vibration Monitoring: Technicians installed programmed portable seismographs to continuously measure and record vibration activity during the workday. The data is uploaded to a server daily. Alerts via email are sent if a vibration is detected above limits, in real time.
On-Site Vibration Monitoring: Technicians install portable seismograph and monitor the site daily (in person) for on-site analysis and notification of the data collected. Crack Monitoring Big Apple has the capabilities to install both Manual and a remote vibration monitoring system. These systems are used to monitor any movement of existing cracks or newly developed cracks.
Demolition, rock removal, excavation, pile driving/drilling, and sheet pile driving are typical construction activities that would cause the most noticeable construction-related vibrations. Expected vibration levels would vary, depending on the equipment being utilized, soil type, building foundation, construction characteristics, and the distance from the construction activity. However, vibration levels at certain locations may be high enough to require mitigation and additional monitoring.
Construction activities would result in varying degrees of ground-borne vibration, depending on the stage of construction, the equipment and construction methods employed, the distance from the construction to vibration-sensitive receptors and geotechnical and soil conditions. Soil and subsurface conditions are known to have a strong influence on the levels of ground-borne vibration. Among the most important factors are the stiffness and internal damping of the soil and the depth to bedrock. Vibration propagation is more efficient in stiff clay soils. Shallow rock may concentrate the vibration energy close to the surface, resulting in ground-borne vibration problems at large distances from the track. Factors such as soil layers and depth to water table can have substantial effects on the propagation of ground-borne vibration.
The Big Apple Group provides continuous vibration monitoring using fully automated seismographs. For remote monitoring, the systems are equipped with a cellular modem to provide automated data reporting and notifications. For direct monitoring applications the Big Apple Group will provide a certified field technician onsite whenever construction activities are taking place.