Energy Variation Characteristics of Exploding Ground Motion within Typical Loess Field of China

摘要

Based on in-situ observational data, we analyzed energy features of strong ground motion induced by short delay blasting in unsaturated loess field through three aspects of time history, frequency spectrum and attenuation. For time histories, the data show exploding ground motion has two essential characteristics, i.e. larger peak ground acceleration (PGA) and shorter duration. Analysis results reveal the effective duration (ground acceleration exceeding a certain magnitude) is the pivotal factor influencing design effects of the blasting. The spectral response, meanwhile, attenuates with the increase of observational distances (apart from the centre of exploding field), especially for those higher frequency components. Values of H/V figured relative features of horizontal component to vertical one of frequency spectrum of exploding ground vibration become greater while distances widen. As exploding energy accumulated, moreover, lower frequency energy distinctly increases and the feature of frequency spectrum of the strong shock gradually approaches an actual seismic oscillation.