土石坝自然电场的三维数值模拟分析

Three-dimensional numerical simulation of spontaneous electricfield of embankment dams

土石坝作为重要的水利工程结构,其安全性与稳定性至关重要。得益于自然电场法对低阻体灵敏的特性,该方法在土石坝、水库渗漏检测中应用广泛。为了研究土石坝自然电场响应特征,首先推导了自然电场的基本方程,构建了有防渗墙无渗漏、无防渗墙无渗漏、有防渗墙有渗漏、无防渗墙有渗漏等4种土石坝模型,并给出对应的模型参数;随后详细分析了土石坝在不同情况下的达西速度、压力水头、含水饱和度、电阻率、自然电位等物性参数分布特征。通过对比有无防渗墙时以及有无渗漏时土石坝自然电场响应特征的差异,揭示了存在防渗墙时和存在渗漏时对自然电场的影响机制,并得出防渗墙可有效降低自然电位的幅值,而存在渗漏通道能够提高自然电位幅值的结论。本研究不仅深化了对土石坝自然电场特性响应特征的理解,也为自然电场法在土石坝渗漏检测中的应用提供了理论支撑。

As an important water conservancy project structure,the safety and stability of embankment dam are very important.Thanks to its sensitivity to low-resistivity bodies,this method is widely used in embankment dams and reservoir leakage detection.In order to deeply analyze the response characteristics of natural electric field of embankment dam,the basic equation of natural electric field is deduced firstly.Four kinds of embankment dam models are constructed,including anti-seepage wall without leakage,no anti-seepage wall without leakage,anti-seepage wall with leakage,and no anti-seepage wall with leakage,and the corresponding model parameters are given.Then,the distribution characteristics of physical parameters such as Darcy velocity,pressure head,water saturation,resistivity and spontaneous potential of earth-rock dam under different conditions are analyzed in detail.By comparing the difference of natural electric field of earth-rock dam with or without cutoff wall and with or without leakage,the influence mechanism of cutoff wall and leakage on natural electric field is revealed,and it is concluded that the existence of cutoff wall can effectively reduce the amplitude of natural potential,while the existence of leakage channel can improve the amplitude of natural potential.The study not only deepens the understanding of the natural electric field characteristics of embankment dams,but also provides theoretical support for the natural electric field method in embankment dam leakage detection.