Vibration Monitoring and Instrumentation
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.
Typical Construction-Related Activities requiring Monitoring
Excavation activities such as grading, spoil loading, hauling, and compaction will all be taking place during the construction of the station utilizing bulldozers, dump trucks, graders, and front-end loaders. Typical construction activities would not produce significant vibration readings, except at locations extremely close to the excavation equipment. Rock removal may take place utilizing hydraulic hammers, micro-explosives, or heavy blasting. These procedures are usually reviewed on a case by case basis with distance and geology of the area being a major factor in vibration transmissions and potential damages.
Underpinning is the process of strengthening the foundation of an existing structure to avoid potential damage and/or settlement during excavation and construction activities being performed adjacent to said structure. There are various methods of underpinning such as Mass Pour of Concrete, Helical Piles & Brackets, and Pile & Beam.
The installation of piles is fairly common in modern construction projects throughout the Northeast corridor. Piles are used to support various types of structures namely buildings, bridges, and various infrastructure. The purpose of using piles is to modify bearing capacity in unsuitable soil condition areas. The installation of piles although sometimes necessary in present-day construction practices cannot be performed without producing noise and vibrations.
Demolition and Implosion of structures is almost a necessity with the urban environment and dwindling amount of real estate available in the Northeastern United States. Demolition and Implosion of structures may, or may not cause a significant amount of vibration that would affect the adjacent structures. The Big Apple Group's Award Winning staff is very versed in critical protection of adjacent structures during demolition and implosion. In addition to being able to complete predictive vibration analysis during the demoltion or implosion activity themselves, the Big Apple Group is able to review your project and determine the amount of control necessary for a safe and successful demolition of the structure or structures required.