4.2 Definition of ground vibration

Vibration transmitted through the ground may cause damage to structures and architectural elements or discomfort to their occupants. The vibration levels at which people become annoyed are well below the levels at which damage occurs. The likelihood of such damage or discomfort may be ascertained by measuring the vibration from a blast close to the location of concern, such as a building or other structure.

For all limits it is necessary to measure in three orthogonal directions, one in the vertical direction and the other two in perpendicular horizontal directions. Such measurements align with most structural members in man-made structures. From such measurements it is possible to derive the vector peak particle velocity (and the peak component particle velocity for each direction).

The magnitude of the vector particle velocity is the amplitude of the vector sum of three time-synchronised velocity components directly measured by an instrument. When not measured directly, it may be determined by the following equation:

vx, vy and vz are the synchronized instantaneous velocity components of the x, y and z axes, respectively. The VPPV is the maximum of vp.

 

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