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Abstract In blasting operations, vibrations constitute unwanted side effects in the surrounding area as a large part of explosive energy dissipates in a form of uncontrolled ground vibration.
There are many variables and site constants resulting in the formation of a complex vibration waveform, and many parameters, controlled and uncontrolled which influence the amplitude of ground vibrations. The propagation of ground vibration is a complex phenomenon; even over small distances, rocks and unconsolidated material are anisotropic and non-homogeneous which restrict theoretical analysis and derivation of propagation law.
State and local regulations require monitoring of blast vibrations. Methods and instrumentation have changed over the years as a result of new developments and needs, and different practices have been adopted, but there is no consensus as to which methods are technically sufficient and practical for all situations.
Ground vibration measurements are made for one of two purposes: to derive predictive equations of generation and propagation and to assess the potential for damage to nearby structures. The common finding of several comprehensive studies was that higher frequencies are the cause of several problems, because, at a given vibration velocity, a higher frequency means a greater acceleration, indicating that any combination of frequency and velocity that yields accelerations above 0.2 g is a potential monitoring problem.
Besides PPV, the frequency is one of the most important factors controlling the response of structures and is key in developing blast designs for tight blasting situations. The blasting limits should be then based on a combination of frequency, peak particle velocity, and the type of structure affected by the blast induced vibration.
Widely available monitoring equipment may not be suitable for urban blast monitoring where structures may be only meters away from a blast location. Current vibration criteria and typical reporting techniques may also not be suitable for the urban environment. This paper summarizes the monitoring and measurement experience gained during a blasting project near the Olympic stadium Tower in Helsinki, Finland.
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