TBM机施工隧道瞬变电磁超前探测研究

Research on the advanced detection of transient electromagnetic in tunnel construction by TBM

在隧道掘进机(TBM)施工隧道内,传统瞬变电磁的装置形式受到了TBM机械的限制,TBM自身的金属构件对二次场衰减电压的采集产生了强烈的电磁干扰。为了克服瞬变电磁法在TBM施工隧道内遇到的困难,在前人工作的基础上,尝试提出了一种基于电性源激发、电场分量采集的施工隧道瞬变电磁超前探测装置形式。针对钻爆法与TBM施工隧道各自不同的工况,利用三维时域有限差分法对单个电性源激励下隧道前方瞬变电磁场的分布规律与响应特征进行了正演模拟。通过对瞬变电磁场的分布规律以及响应特征进行分析,认为所述的电性源发射装置不仅可以在钻爆法施工隧道内使用,并且具有在TBM施工隧道内进行隧道超前预报的能力。

When the tunnel passes through the complex strata with bad geological development,it often encounters geological disasters such as water inrush,mud inrush,collapse and roof fall.During the construction of the tunnel,the advanced geological prediction for the adverse geological disasters such as water and mud inrush has become an important issue to ensure the construction safety.Transient electromagnetic method has been widely used in the prediction of tunnel and underground cavern construction period.However,with the increasingly complex construction environment,the application of traditional TEM is restricted by various factors.For example,in TBM construction tunnel,the traditional transient electromagnetic device form is limited by TBM machinery,and the metal components of TBM produce strong electromagnetic interference to the collection of secondary field attenuation voltage,which makes this kind of method difficult to apply to TBM construction tunnel at present.In order to overcome the difficulties encountered by TEM in TBM tunnel construction,the authors,based on previous work,attempted to put forward a type of TEM advanced detection device based on electrical source excitation and electric field component acquisition.According to the different working conditions of drilling and blasting method and TBM construction tunnel,the three-dimensional finite-difference time-domain method is used to simulate the distribution and response characteristics of transient electromagnetic field in front of the tunnel excited by a single electrical source.Based on the analysis of the distribution and response characteristics of transient electromagnetic field,the authors hold that the single electrical source launching device not only can be used in the tunnel construction by drilling and blasting but also has the capability of advanced prediction in the tunnel construction by TBM.