A scaled charge weight superposition model for rapid vibration estimation

Rapid vibration estimation usually relies on charge weight scaling laws. These empirical curves that fit field data are sometimes involved in linear superposition models. A scaled charge weight superposition model combines the traditional charge weight scaling law within a linear superposition framework so that the influence of timing and blast design parameters may be assessed. The model involves an extra parameter of time overlap and poses a partial explanation for the over-estimation of blast vibration levels sometimes predicted by linear superposition models. It is suggested that the time overlap parameter be determined from measured vibration data. The new model recovers the Holmberg-Persson equation for near-field vibration from a single blast hole. Three examples compare the predictions of the new model with those from a linear superposition model. The results indicate a consistent, but not compelling demonstration of the predictive power of the scaled charge weight superposition model. Further verification studies are recommended using a wide range of blast types and scaled distances to points of interest. The new model lies between a traditional charge weight scaling law and a linear superposition model. It ignores waveform superposition explicitly but assumes non-linear interaction between adjacent charges in a blast within a user-defined time window. In that sense, the scaled charge weight superposition model offers an alternative method for rapid vibration estimation.