AEL VibrAc

Vibrazioni e aria sopra di pressione (Airblast) Calculator

DISCLAIMER AND INDEMNITY:

Any recommendations given by The Publisher in respect of this software are given in good faith based on information provided.

The Publisher does not however warrant that particular results or effects will be achieved if the recommendations are implemented, due to potentially unknown aspects and/or conditions.

The Publisher further does not accept liability for any losses or damages that may be suffered, as a result of the customer/user acting, or failing to act, on the recommendations given.

Vibration and Air Over Pressure (Airblast):

Blasting Vibration is a general term for the diverse physical waves (manifesting as airblast and ground vibration) that arise from blasting, and impact on structures, raising concern in the public.

With the steady encroachment of residential areas onto quarrying and mining operations there has been a corresponding increase in the number of complaints about blasting operations and legal claims for damage. It is important to grasp whether these complaints are:

Related to real damage, or

More a matter of human alarm at the noise and rumble of blasting, although vibration levels are well below the damage thresholds, or

Opportunistic claims

Much of the foundational research into airblast, ground vibration and consequential damage was underway from the 1950’s by the now defunct US Bureau of Mines (USBM) and continues worldwide. The USBM work is still widely accepted and is introduced here as background. In 1983 the USA OSMRE (Office of Surface Mining Reclamation and Enforcement) issued regulations based on the USBM work, modified in the light of consultation. These make good sense and form the base for the Publisher’s recommendations.

More recently, with the increasing emphasis on human comfort levels and extreme caution with sensitive situations, guidelines are often more conservative, and it is important to consult widely with affected parties and the authorities involved.

It is to the blaster's advantage to understand that many complaints and legal claims received as the result of blasting could have been avoided if thought and effort had been given to:

Good public relations by ensuring both production personnel and the local community have an understanding of the nature of airblast and ground vibration

Good blast design that minimises the generation of high amplitude, low frequency air and ground waves

Correct use and emplacement of equipment to monitor and measure disturbance, with impartial analysis and archiving of records

Conducting pre-blast surveys so as to minimise false claims and facilitate rapid resolution of situations

Where there has been no suitable monitoring or test work, in our experience acceptable vibration levels have always been obtained when using the following table. Freak geological conditions could however result in unexpected concentration or transmissions of ground vibrations especially in waterlogged ground and the table CANNOT therefore be viewed as infallible. If an entirely safe table for all possible conditions are required the equation given by the USBM is applicable.

Equations used in this application is limited to the following:

Vibration:

PPV=a*(D/√E)^b

Air Overpressure/Airblast:

L=a-b*log⁡(D/(∛E))

Please refer to the AEL Mining Services Surface Blasting Handbook Application for further detail relating to suggested maximum PPV/Vibration levels.

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