Increasing building density in urban areas has caused the necessity of carefully and diligently monitoring structures within and around construction sites. Government infrastructures due to a lack of available surface space are now increasingly going either underground or above grade level or overhead to allow for minimal intrusion into private high value therefore highly taxed properties.
In order to minimize damage undue delays caused by legal and moral issues; and, added expense incurred due to repairs and rehabilitation; Construction companies are increasingly relying on the capabilities of third party monitoring companies such as QCL (Quality Control laboratories, LLC) to provide them with reliable and minimally invasive procedures to monitor horizontal movements, settlement or vertical movements, vibrations, tilt, inclination, water intrusion, and a host of other readily observable geo-characteristics that could forewarn, and provide advance warning, indicative of an impending major damage to structures within and around an active construction area. This advance warnings or indicators could provide sufficient time to perform actions that could prevent or mitigate any damage that may happen in time.
Monitoring application could either be within the construction or jobsite to ensure the safety of workers, equipment and materials; or, to adjoining structures within the area of influence of the activity to safeguard it from damage and to ensure the safety of its occupants or users .
Monitoring comes in a variety of ways which may be roughly classified under three Monitoring Modes:
- Movements – which may include horizontal, vertical (settlement) or skewed movements and are the direct effect of construction activities, specially tunneling. excavations and underpinning activities. These movement may be substantial as to cause damage or imperceptible but just the same would be worth monitoring as it may cause damage and or mis-alignment that may compromise the overall integrity of structures.
- Vibration – are movements that are cyclic or rhythmic in character that produces undue strain to structures eventually causing damage; may be in the form of a wave or a back and forth or sideways disturbances, lasting from milliseconds or up to several minutes. Vibration even at low intensities may be detrimental or harmful if it occurs for a long enough
- Water Intrusion – and its accompanying effects, such as soil expansion or contraction due to water pressure or the lack of it; and, other occurrences such as soil migration, flow, liquefaction, solution and dissolutions, and probable vapor