爆破地震作用下的老旧砌体结构动力特性分析  

Analysis of Dynamic Characteristics of Old Masonry Structure under Blasting-induced Earthquake

作　　者：黄俊 夏界宁 罗松 HUANG Jun;XIA Jie-ning;LUO Song(Hubei Province Key Laboratory of Earthquake Early Warning,Hubei Earthquake Agency,Wuhan 430071,China;Wuhan Institute of Seismic Scientific Instrument Co.,Ltd.,Wuhan 430071,China)

机构地区：[1]湖北省地震局地震预警湖北省重点实验室,武汉430071 [2]武汉地震科学仪器研究院有限公司,武汉430071

出　　处：《爆破》2024年第2期185-193,202,共10页Blasting

基　　金：湖北省重点研发专项(ZZCXHZYF2022000391);湖北省高价值知识产权培育工程(0210);中震双创研发基金(ZZSC-2022-G03)。

摘　　要：城市内老旧砌体结构多但抗震性能较差,在爆破作用下可能产生破坏。为研究爆破作用下老旧砌体的动力特性,在爆破现场附近的老旧砌体结构上布设强震仪,以观测爆破地震波对结构的瞬时作用以及长期爆破作用下的累积损伤效应。通过对爆破加速度和速度记录进行时域和频域分析比较,认为爆破速度记录相比爆破加速度记录可以更好地识别出砌体结构的动力特性,且爆破地震速度对砌体结构横向的共振影响最大。采用对比分析法,分别用爆破地震速度和地脉动加速度记录识别老旧砌体结构的动力特性,发现两种方法都能近似地识别出砌体结构的低阶平动和扭转频率,但采用爆破速度计算的自振频率比地脉动法要小1.8%~3.4%,这主要是因为爆破振动更能反映在较大振动作用下结构的响应,频繁的爆破可能导致老旧砌体结构出现非线性反应。通过监测结构自振频率在长期爆破作用下的变化,发现虽然单个爆破振动能满足《爆破安全规程》的安全要求,但在长期爆破作用下,结构1阶扭转频率、2阶横向和纵向频率随爆破次数的增加分别减少了4%、3.6%和5.2%,因此在爆破安全监测中应考虑长期爆破作用对老旧砌体结构等抗震能力较差建筑的累积损伤效应。In urban centers,there are numerous old masonry buildings that possess poor seismic performance and may suffer damage under the effects of blasting.To investigate the dynamic characteristics of these structures when subjected to blasting,a strong motion instrument was installed near a blasting site on an old masonry building.This allowed for observation of both instantaneous and cumulative damage effects on the structure.By analyzing records of blasting acceleration and velocity in both time and frequency domains,it is concluded that the dynamic characteristics of the masonry structure can be better identified using blasting velocity rather than acceleration.Additionally,it is found that the transverse resonance of the masonry structure is most influenced by the blasting seismic velocity.Furthermore,both blasting seismic velocity and acceleration can approximately identify low order translational and torsional frequencies of the masonry structure.However,when calculating natural vibration frequency,it is observed that using blasting velocity yields a lower value(1.8%~3.4%lower)compared to calculations based on ground pulsation methods.This discrepancy arises because blast vibrations provide a more accurate reflection of structural response under larger vibrations.Moreover,frequent blasts may induce nonlinear responses in old masonry structures.By monitoring changes in natural vibration frequency over time due to long-term exposure to blasts,it is determined that with increasing blast frequency,first-order torsional frequency decreases by 4%,second-order transverse frequency decreases by 3.6%,and second-order longitudinal frequency decreases by 5.2%.These reductions occur even though individual blasts meet safety regulations,thus highlighting the importance of considering cumulative damage effects from long-term exposure to blasts for old masonry structures with poor seismic capacity during safety monitoring.

关 键 词：爆破地震波 老旧砌体结构 自振频率 累积损伤效应 爆破安全评估 

分 类 号：TD235[矿业工程—矿井建设] X932[环境科学与工程—安全科学]