隧道超前探水的动电效应数值模拟研究

Numerical Simulation of Electrokinetic Effect of Tunnel Advance Water Exploration

摘要: 隧道超前预报是工程领域重要的前沿问题。前人使用过多种方法探测隧道掘进过程中的含水构造，但是效果一般。动电效应作为一种新的地球物理方法，兼具地震方法和电磁方法的优点，有望在隧道超前探水问题上提供新的有效的思路。本文基于有限元方法对隧道探水模型中动电效应进行数值模拟。结果表明，动电效应具有其他方法不可比拟的优势。由于本方法中弹性波场与电磁波场具有天然的耦合关系，因此可以进行相互验证，从而更加快速准确地提取波场信息；震电效应中可以通过接收排列记录的位移场判断含水构造相对位置，利用电场提取含水构造轮廓信息，再利用多点激发获得的界面响应信息进行目标体定位；电震效应更是由于位移场特殊的传播规律带给我们新的思路，从而实现仅需一次单点激发即可实现含水构造定位的目标。本文的数值模拟工作为使用动电效应进行隧道超前探水提供了施工方案和分析方法，对探测影响隧道掘进的含水构造具有借鉴价值。

Abstract: Advance forecast of tunnel is an important frontier problem in engineering field. Many methods have been used to detect water-bearing structures during the tunnel drum, but the results were not satisfactory. As a new geophysical method, electrokinetic effect has the advantages of both seismic method and electromagnetic method, which is expected to provide a new and effective idea for tunnel advanced exploration. In this paper, the electrokinetic effect of tunnel water ex-ploration model is numerically simulated based on finite element method. The results show that electrokinetic effect has incomparable advantages over other methods. Due to the natural coupl-ing relationship between elastic wave field and electromagnetic wave field in this method, mutual verification can be carried out, so that wave field information can be extracted more quickly and accurately. As for seismoelectric effect, the relative positions of water-bearing structures can be determined by receiving the displacement fields recorded in alignment, and the profile information of water-bearing structure can be extracted by electric field, and the target body can be located by using the interface response information obtained by multi-point excitation. The electroseismic effect brings us a new idea due to the special propagation law of displacement field, so as to realize the goal of water-bearing structure positioning with only a single point of excitation. The numerical simulation work in this paper provides a construction scheme and analysis method for tunnel advance water exploration using electrokinetic effect, which has reference value for detecting water-bearing structures affecting tunnel driving.