What is ground vibration in blasting?
What is ground vibration in blasting?
Ground vibrations originating from bench blasting may cause damage to slopes, structures, and underground workings in close proximity to an operating open-pit mine. It is important to monitor and predict ground vibration levels induced by blasting and to take measures to reduce their hazardous effects.
How is ground vibration measured?
Ground vibration monitors use a transducer, also called a geophone, to measure vibrations. To properly measure these vibrations, securely couple the geophone to either the ground or a structure. This ensures that the geophones sense all the energy in the ground.
How do you calculate PPV blasting?
The relationship between PPV and scaled distance (D) can be written as(1) v = k D − b where v is the PPV (m/s); D is the scaled distance (m/kg1/2), which is defined as the ratio of distance from charge point, R (m), to the square root of charge mass, Q (kg), expressed in TNT net equivalent charge weight, i.e. D = R/Q1/ …
What is ZC frequency?
The zero-crossing frequency (ZC frequency) is an approximation of the frequency of the peak particle velocity. It is computed by taking the inverse of the period between two consecutives zero crossings at the peak.
What causes airblast?
Airblast is also caused by the venting of gases through cracks and fractures in the rock mass being blasted (GRP), or from the ejection of stemming material (SRP) used to confine the explosives in the blasthole.
How does vibration meter work?
A vibration meter is a form of an electronic device and is also known as an analyzer. It can process the vibration signals. The sensor generates the voltage signal when it is shaking on the machine. This signal is transmitted through the cable to the vibration meter.
What is a vibration meter?
A vibration meter is typically a portable device with a memory for storing measurements. Most vibration meter models feature a built-in data logger for collecting and recording vibration measurement data over time. In this way, vibration measurement data can be acquired with great precision.
What is scaled distance blasting?
Scaled Distance (SD) is a scaling factor that relates similar blast effects from various charge weights of the same explosive at various distances. Scaled distance is calculated by dividing the distance to the structure of concern by a fractional power of the weight of the explosive material.
What is PPV in vibration?
Ground vibration is measured in terms of Peak Particle Velocity (PPV) with units in mm/s or mm/s-1. It should be noted that the PPV refers to the movement within the ground of molecular particles and not surface movement.
What is dominant frequency in vibration?
The dominant frequency there is about 42 Hz, with a low peak particle velocity of 0.185 in/sec. Thus, most vibration reports would indicate that this vibration would be “non-damaging”.
