【摘要】 通过在黄土高原地区典型震陷性黄土场地实施的微差爆破试验,分析研究爆破引发地震动的时程特征、衰减规律和频谱特性。研究结果表明,微差爆破引发的黄土场地强地面运动具有瞬时较大地震动峰值加速度(PGA)和较短持时的基本特征;有效持时是影响震源设计效果的主要因素,爆破地震动具备持时任意接续特征,利用简单接续即可获得持时较长、频谱特征保持一致的合成时程,该时程对测试不同土体(结构)动力响应特征更为有利。随着距场地中心渐远,地震动频谱响应皆有减弱趋势,频率越高减势越明显;同时,频谱H/V值逐渐增大,反映了水平分量与垂直分量之间能量比值的变动关系。爆破的冲击型能量累积过程中,引发强地面运动的低频能量逐渐丰富,与实际地震动特征渐趋相近。更多还原

【Abstract】 Based on a short delay blasting executed in the typical seismic loess field of Loess Plateau,the time histories characteristics,attenuation laws and frequency spectrum features of ground motion induced by the blasting are investigated.In-situ observation data show that exploding ground motion in loess field has two essential characteristics evidently,i.e.an instantaneous large peak ground acceleration(PGA) and a shorter duration.Analysis results of exploding ground motions reveal that effective duration is the most important factors to influence design effects of a short delay blasting.Independent exploding events in the blasting process have an evident feature that the time histories could be connected each other discretionarily.As a result,the duration of exploding ground motion may be lengthened through this kind of connection work.These connection results of time histories would not influence the spectral characteristics of ground motion induced by the short delay blasting.The new time histories are better in the application of laboratory and field tests to understand the response behaviors of soils and structures.The spectral response of blasting ground motion tends to attenuate with the increase of distance between the center of exploding field and observation points,especially for the high frequency ground motion,which has a greater reduction distinctly.The H/V values of frequency spectrum,meanwhile,become greater with the observational distances increase gradually.This phenomenon figures the variation features between horizontal component and vertical component of exploding ground motion.As the exploding energy accumulates,lower frequency energy of ground motion associates with the blasting increases gradually;and the frequency spectrum features of the ground shock approach an actual seismic oscillation by degrees.更多还原