浅埋隧洞下穿既有建筑物爆破施工振动分析

Analysis of Blasting Vibration of Shallow Buried Tunnel under Existing Building

浅埋输水隧洞在地质条件复杂、下穿众多重要建筑物的情况下进行爆破作业时爆破振动极易对地表建筑物造成破坏,控制爆破是在保证工程效率的前提下减少对既有建筑物影响的关键技术难点。以输水隧洞下穿公路(经寿山禅寺、寿峰寺段)工程为研究对象,采用数值模拟及现场振动监测研究爆破开挖施工下对地表古建筑物的影响及振动衰减特征。结果表明:基于数值模拟的振动效应地震波在介质中传递时,由于塑性区单元的作用,振速随着时间推移及爆心距的增加而不断衰减,且由于入射纵波与竖直方向的夹角及爆心距的共同作用导致垂直方向的振速最大;寿山禅寺和寿峰寺振速峰值模拟误差分别为3.7%、2.3%结果较吻合,保证了既有建筑物的安全;监测结果可知,由于岩体阻尼较大对信号具有一定的选择吸收作用,信号在岩体中传递的过程产生能量损耗,振速不断衰减,模拟结果与监测结果振速衰减规律一致;另外采用线性拟合得出了精度较高的萨氏地震波衰减公式,表明了数值模拟方法对提前预测振动效应具有可行性,结论为后续爆破施工方案设计提供参考借鉴。

Ground vibrations induced by blasting in a shallow buried diversion tunnel can easily cause damage to existing buildings above under complex geological conditions.Controlled blasting is a key technical difficulty to reduce the impact on existing buildings under the premise of ensuring engineering efficiency.In this paper,the influence of blasting excavation on ancient buildings and the characteristics of vibration attenuation are studied by using numerical simulation and on-site vibration monitoring,based on the project of water diversion tunnel under the highway(through Shoushan Temple,Shoufeng Temple section).The results show that the vibration velocity decreases with time and distance from blast center due to the action of plastic zone elements.The combined effect of the angle between the incident p-wave and the vertical direction and the distance from the blast source leads to that the vibration velocities in vertical direction are greater than other directioins.The simulation errors of peak vibration velocites of Shoushan Temple and Shoufeng Temple are 3.7%and 2.3%,respectively,which are consistent with the field test data.According to the monitoring data,due to the large damping of rock mass,the signals have a certain selective absorption effect,and the transmission process of the signals in rock mass produces energy loss,and the vibration velocity is constantly attenuated.The simulation results are consistent with the monitoring results.In addition,the linear fitting method is used to obtain the Sadovsky formula for seismic wave attenuation,which indicates that the numerical simulation method is feasible to predict the vibration effect in advance.