邻近隧道管片结构对基岩和孤石爆破的振动响应特征研究

The vibration response characteristics of the adjacent tunnel segments during bedrock and boulder blasting

华南沿海地区盾构隧道施工时,经常会遇到球状风化岩体和基岩侵入隧道开挖断面的情况。在盾构直接掘进前,可采用水下钻孔爆破的方法对侵入基岩和孤石进行预处理。然而,这种无自由面爆破产生的振动效应及其对邻近结构物的影响不可忽视。基于某海底取水隧洞工程,重点研究邻近已建隧洞管片结构对基岩和孤石爆破的振动响应特征,对监测数据进行对比分析,得出不同衬砌结构、测点位置及岩性条件下地震波衰减参数,并对现行爆破振动控制标准进行讨论。研究结果表明:地震波传播到管片壁内表面时,会发生突变放大效应,爆破振动对隧洞迎爆侧的影响要大于背爆侧,相对于其他爆破工程,无自由面条件海底孤石爆破产生的爆破振动更大。结构物的振动破坏不仅取决于地震波的质点振动速度,还与地震波的幅值、频谱、结构自身的动态特性、爆破自由面和爆破持续时间等诸多因素有关。

Shield tunnel construction usually encounters spherical weathering rock mass and bedrock intrude into the excavation section in coastal areas of south China.Prior to the shield tunneling,the method of underwater drilling and blasting can be used to pre-treat the bedrock and boulder.However,the vibration effect produced by this type of blasting with no free surface and its impact on adjacent structures cannot be ignored.Based on an undersea intake tunnel project,this paper focused on studying the vibration response characteristics of bedrock and boulder blasting of the pipeline segment adjacent to the built tunnel,making comparative analysis of the monitoring data,obtaining seismic wave attenuation parameters under different lining structures,measuring point position and lithological characteristics,and discussing the current standards of blasting vibration control.According to the study,the abrupt amplification effect occurs when the seismic wave propagates to the inner surface of the segment,and the impact of blasting vibration on the blasting side of the tunnel is greater than that of the back blasting side.Compared with other blasting engineering applications,the blasting vibration generated by sealed solitary rock blasting under the condition of no free surface is greater.The vibration damage of structure not only depends on the particle vibration of seismic wave,but is also related to the amplitude,spectrum,dynamic characteristic of the structure itself,and the blasting free surface and duration time of blasting.