Structure Response And Damage Produced By Ground Vibration From Surface Mine Blasting

The Bureau of Mines studied blast-produced ground vibration from surface mining to assess its damage and annoyance potential, and to determine safe levels and appropriate measurement techniques. Direct measurements were made of ground-vibration-produced structure responses and damage in 76 homes for 219 production blasts. These results were combined with damage data from nine other blasting studies, including the three analyzed previously for Bureau of Mines Bulletin 656. Save levels of ground vibration from blasting range from 0.5 to 2.0 in/sec peak particle velocity for residential-type structures. The damage threshold values are functions of the frequencies of the vibration transmitted into the residences and the types of construction. Particularly serious are the low-frequency vibrations that exist in soft foundation materials and/or result from long blast-to-residence distances. These vibrations produce not only structure resonances (4 to 12 Hz for whole structures and 10 to 25 Hz for mid walls) but also excessive levels of displacement and strain.

The entire field of construction-induced vibrations - including advances in earthquake engineering, nuclear blast protective design, and construction and mine blasting - is covered in this work. Frequency of vibration and strain form the foundation for the presentation of the material.

Blasting is very important process for mining operation and a lot of explosive is used for this purpose. The blasting process and usage of explosives, however, remain a potential source of numerous human and environmental hazards. Various studies indicate that fragmentation accounts for only 20-30% of the total amount of explosive energy used. Rest of the energy is lost in the form of ground vibration, fly rock, air overpressure and noise. The specific problem associated with ground vibrations represents the human response to them. Blasting vibrations may also cause a significant damage to nearby buildings or various structures. In this project blast vibration study is done and it is interpreted for its effects in reference to the standards set by DGMS. The study has been done with the help of geophones and Blastmate8.0 software. First of all the blasting operations were monitored through geophones at distances of 100m, 200m and 300m. The data obtained from the instrument were interpreted by Blastmate software and the graphical output was obtained from it. The Peak Particle Velocity (PPV), maximum charge per delay, air over pressure was recorded for each blast. After that the various observations were compared with the standards to determine the conclusion. From the analysis of blasts vibration at the mines it was determined that the vibration level was less than 5 mm/sec for the blasts when recommended amount of charge per delay or safe charge per delay was used. The air overpressure value determined was in between 114 & 127.6 dB (L). The results determined from the project indicates that the peak particle velocity, air overpressure generated due to blasting were within the limits. The safe charge per delay for the blasting operation was determined from the study.