隧道变形过程中电磁辐射强度参数的变化规律

根据丽江至香格里拉铁路中义隧道变形及电磁辐射的现场监测资料,对隧道变形过程中的电磁辐射特性及电磁辐射强度极大峰值事件数N、超过强度平均值的极大峰值事件数M与隧道水平收敛变形的关系进行了统计分析。研究表明:(1)电磁辐射最大强度平均值E在初期支护破坏前,随隧道变形的增大而增大,初期支护破坏后,随隧道变形的增大而减少,电磁辐射最大强度平均值先升后降的出现时间与初期支护破坏的时间接近。(2)电磁辐射强度极大峰值事件数、超过强度平均值的极大峰值事件数的波动速率V_N、V_M与隧道变形速率呈正线性相关关系;电磁辐射强度极大峰值事件数、超过强度平均值的极大峰值事件数的百分比λ_N、λ_M与隧道累计变形呈正线性相关关系。结论对深化地下洞室变形过程中的电磁辐射特性的认识,提高电磁辐射监测技术的现场应用水平具有指导意义。

Variation law of electromagnetic radiation intensity parameters during tunnel deformation

Based on the on-site monitoring data of deformation and electromagnetic radiation of Zhongyi Railway Tunnel of Lijiang-Shangrila, a statistical analysis was done on the characteristics of electromagnetic radiation, the relationship between the events of maximum peaks of EME intensity (N) and horizontal convergence deformation, and the relationship between the events of maximum peaks of EME intensity exceeding the average intensity (M) and horizontal convergence deformation during the deformation of the tunnel. The results show that: 1) The maximum average value of electromagnetic radiation intensity (E) increased with deformation expanding before the initial support yielded, while there was an opposite trend after the initial support yield failure. The turning time point of rising first and then falling of the maximum average value of electromagnetic radiation intensity was close to the initial support yielding. 2) The events fluctuation rate of maximum peaks of EME intensity ( ) and maximum peaks of EME intensity exceeding the average intensity ( ) were positively correlated with convergence deformation rate of the tunnel. There were positively linear relationships between the percentage of events of the maximum peaks of EME intensity ( ), the maximum peaks of EME intensity exceeding the average intensity ( ) and the cumulative deformation of the tunnel as well. Research conclusions are important in the perspective of advancing the understanding of electromagnetic radiation characteristics during the deformation process of underground cavern and enhancing the field application level of monitoring technology of electromagnetic radiation.