What is a scaled distance?
A ratio used to predict ground vibrations. As commonly used in blasting, scaled distance is the ratio of the distance from the blast, in metres, to the square root of the maximum instantaneous charge weight, in kilogrammes.
How do you calculate scaled distance?
Trial blasts are detonated to determine the safe-scaled distance (= R/W1/2, where W is the weight of charge per delay of detonators and R is the distance from the blasting pattern) to control peak particle velocity according to the nature of the structures.
How do you calculate vibration distance?
The Scaled Distance for Vibration Control calculates the scaled distance when we have prior information of maximum weight and distance and is represented as v = H*(D/sqrt(W))^(-β) or Scaled distance = Constant of scaled distance*(Distance/sqrt(Maximum weight))^(-Constant of scaled distance).
What is scaled distance blast?
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.
How do you scale measurements?
The scale factor is commonly expressed as 1:n or 1/n, where n is the factor. For example, if the scale factor is 1:8 and the real measurement is 32, divide 32 ÷ 8 = 4 to convert. To convert a scaled measurement up to the actual measurement, simply multiply the smaller measurement by the scale factor.
What is peak vector sum?
The peak vector sum (PVS) is usually also quoted; it is simply the square root of the sum of the squares of the PPV values in all three vector directions measured by the seismograph. PVS is a “scalar” quantity, i.e. one with only a value, which is always larger than the individual PPV vector values.
What is G value in bearing?
Vibration acceleration is measured in G (9.81 m/s²) but you will often see these measurements converted to decibels (dB). A low noise/vibration rating is achieved by paying particular attention to the surface finish of the raceways and balls, the roundness of the rings and balls and correct cage design.
What causes ground vibration?
These vibrations are caused by everything from pile driving to blasting to operating heavy equipment on-site. Every time these vibrations travel through soil, they do so in elastic waves that make soil looser and less compact, potentially causing nearby foundations to shift errantly.
How is peak particle velocity calculated?
The PPV value at a blasting site is obtained by means of regression between the PPV and the scaled distance (SD). The SD is a ratio of the distance between the shot and the measuring station (m); and square root of the maximum charge per delay (kg).
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.
What is a scale factor on a map?
Grid Scale Factor Grid Scale Factor, often simply called “Scale Factor” is a measure of distortion at a given point on a projected map. The scale factor is not cartographic scale, but a factor used to calculate actual ellipsoidal distances rather than distances on the projected surface.
How do you calculate scale factor of a shape?
Scale Factor Formula The formula for scale factor is given by: Dimensions of Original Shape x scale Factor = Dimension of new shape Scale factor = Dimension of New Shape/Dimension of Original Shape
What is the difference between scale factor and convergence?
The scale factor is not cartographic scale, but a factor used to calculate actual ellipsoidal distances rather than distances on the projected surface. Convergence is the angle of difference in direction from Grid North to True North.
What is an example of scale factor problem?
Scale Factor Problem For example, there’s a rectangle with measurements 6 cm and 3 cm. Both sides of the rectangle will be doubled if we increase the scale factor for the original rectangle by 2. I.e By increasing the scale factor we mean to multiply the existing measurement of the rectangle by the given scale factor.