Significance of 8-Millisecond Delay Interval Criterion in Blast Vibration Prediction
Current regulations to control blast vibration for the safety of concerned structures are based on peak particle velocity, though; the frequency is incorporated in the regulations. The simplest method used to predict ground vibration from surface blasting is scaled distance which is the distance from the blast to the concerned location divided by square root of the maximum explosives weight in a delay. It has become common practice in various regulations, criteria and project specifications to consider the maximum explosives weight per delay which detonates within any given 8ms interval. This practice apparently dates to the early 1960s following a US Bureau of Mines report of test with delay intervals of 9,17 and 34ms. The test showed them to be effective in reducing vibration, but no extensive tests were conducted to validate the findings.A systematic study was conducted to investigate the significance of 8ms delay criterion. Eighteen blasts were conducted at three coal mines in India with delay intervals of 8ms,17ms and 25ms at the same blast bench face while keeping all the blast designs and explosives properties identical for a set of experiments. The result indicated that the practice of 8ms delay interval criterion for separation of waves is insufficient and caused constructive reinforcement (addition) of vibrations. The delay interval of 17ms between two detonations resulted into lower level of vibration and provided adequate time for non superimposttion of waves.
blast vibration delay interval rock fragmentation explosives seismic waves
P. K. Singh M. P. Roy A. Sinha
Central Mining Research Institute, Dhanbad, India
国际会议
The Asian-Pacific Symposium on Blasting Techniques(亚洲太平洋地区爆破技术研讨会)
昆明
英文
459-466
2007-05-08（万方平台首次上网日期，不代表论文的发表时间）